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NCEA L1 Science study materials
NCEA L1 Science study resources

NCEA L1 Science practice questions

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Question 1Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student builds a circuit with a 6.0 V battery and a 3.0 Ω resistor. What current flows through the resistor?

  1. 9.0 A
  2. 0.50 A
  3. 2.0 A Correct answer.
  4. 18 A

Explanation

Ohm's law states that current equals voltage divided by resistance (I = V/R). Dividing 6.0 V by 3.0 Ω gives 2.0 A. The other values come from multiplying or inverting the quantities incorrectly.

Question 2Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Why is the heating element of a kettle made from a material with high resistance rather than a low-resistance conductor such as copper?

  1. High resistance stops the current completely until the water boils
  2. High resistance converts more electrical energy into heat for the same current Correct answer.
  3. High resistance allows more charge to pass through the element
  4. High resistance reduces the current so the kettle draws less power

Explanation

Power dissipated as heat in a resistor is P = I²R, so for a given current a higher resistance releases more thermal energy. A copper element of low resistance would waste little energy as heat and mostly conduct current. This is why heating elements use alloys with relatively high resistance.

Question 3Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which statement correctly describes the magnetic field produced by a straight current-carrying wire?

  1. The field lines form circles around the wire in planes perpendicular to it Correct answer.
  2. The field lines run parallel to the wire along its length
  3. The field lines point radially outward from the wire like spokes
  4. The field lines exist only at the ends of the wire

Explanation

A current in a straight wire produces a magnetic field whose lines are concentric circles around the wire. The direction is given by the right-hand grip rule, with the thumb along the current. The field strength decreases with distance from the wire.

Question 4Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

An electromagnet is made by winding wire around an iron nail and connecting it to a battery. Which change would strengthen the electromagnet?

  1. Reversing the battery connections
  2. Increasing the number of turns of wire around the nail Correct answer.
  3. Using thinner wire with the same number of turns
  4. Replacing the iron nail with a plastic rod

Explanation

The strength of an electromagnet increases with the number of turns and with the current in the coil. Adding turns means more current-carrying loops contributing to the magnetic field. A ferromagnetic core such as iron also concentrates the field.

Question 5Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A 12 V supply is connected across a 4.0 Ω resistor. How much power is dissipated in the resistor?

  1. 36 W Correct answer.
  2. 48 W
  3. 0.33 W
  4. 3.0 W

Explanation

Power can be found using P = V²/R, giving 144/4.0 = 36 W. Alternatively, the current is 3.0 A and P = VI = 12 × 3.0 = 36 W. Both methods give the same result.

Question 6Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Two identical lamps are connected in parallel to a battery. How does the brightness of each lamp compare with a single lamp connected alone to the same battery?

  1. Each lamp is dimmer because the current is shared equally between them
  2. Each lamp has the same brightness because each receives the full battery voltage Correct answer.
  3. Each lamp is brighter because the total current is larger
  4. Each lamp is dimmer because the total resistance is lower

Explanation

In a parallel circuit each branch is connected directly across the supply, so each lamp receives the full battery voltage. Since the lamps are identical, each draws the same current and glows with the same brightness as when alone. The battery supplies more total current, but this is shared between branches.

Question 7Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which unit is used to measure electric current?

  1. Volt
  2. Watt
  3. Ampere Correct answer.
  4. Ohm

Explanation

Electric current is the rate of flow of electric charge and is measured in amperes (A). Volts measure potential difference, ohms measure resistance, and watts measure power. One ampere equals one coulomb of charge passing a point each second.

Question 8Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A fuse is included in a household appliance circuit. What is the purpose of the fuse?

  1. To convert alternating current into direct current
  2. To store electrical energy for later use
  3. To increase the voltage supplied to the appliance
  4. To melt and break the circuit if the current becomes too large Correct answer.

Explanation

A fuse contains a thin wire that melts when the current exceeds its rating, breaking the circuit. This protects wiring and appliances from overheating and fire caused by excessive current. The fuse must be rated just above the normal operating current of the appliance.

Question 9Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

In New Zealand homes, the metal casing of an appliance is connected to earth. Why does this protect a person who touches a faulty appliance?

  1. The earth wire provides a low-resistance path so a large current blows the fuse or trips the breaker Correct answer.
  2. The earth wire reduces the voltage of the live wire to zero permanently
  3. The earth wire insulates the casing from the live wire
  4. The earth wire carries the normal operating current back to the supply

Explanation

If the live wire touches the metal casing, the earth wire provides a low-resistance path to the ground. A large current flows and quickly blows the fuse or trips the circuit breaker, disconnecting the supply. This prevents a person touching the casing from receiving a serious shock.

Question 10Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which material would be the best choice for the core of an electromagnet in a door lock?

  1. Copper
  2. Rubber
  3. Glass
  4. Soft iron Correct answer.

Explanation

Soft iron is ferromagnetic and easily magnetised and demagnetised, making it ideal for an electromagnet core. It concentrates the magnetic field produced by the coil, increasing the strength of the electromagnet. When the current is switched off, the soft iron loses most of its magnetism.

Question 11Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student connects a 9.0 V battery to two 6.0 Ω resistors in series. What is the current in the circuit?

  1. 1.5 A
  2. 3.0 A
  3. 0.25 A
  4. 0.75 A Correct answer.

Explanation

In series, resistances add, so the total resistance is 6.0 + 6.0 = 12 Ω. Using I = V/R gives 9.0/12 = 0.75 A. The same current passes through both resistors in a series circuit.

Question 12Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

How does the resistance of a metal wire change when its length is doubled, assuming its thickness and temperature stay the same?

  1. It halves
  2. It becomes four times larger
  3. It doubles Correct answer.
  4. It stays the same

Explanation

Resistance is directly proportional to length, so doubling the length doubles the resistance. This is because charge carriers must travel further through the lattice and collide more often. Thickness affects resistance differently: doubling the cross-sectional area halves the resistance.

Question 13Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which statement about the magnetic field around a bar magnet is correct?

  1. Field lines emerge from the north pole and enter the south pole outside the magnet Correct answer.
  2. Field lines cross each other where the field is strongest
  3. Field lines exist only inside the magnet
  4. Field lines emerge from the south pole and enter the north pole outside the magnet

Explanation

By convention, magnetic field lines point away from a north pole and towards a south pole outside the magnet. Inside the magnet they run from south to north, forming closed loops. Field lines never cross, because the field has a single direction at any point.

Question 14Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

An electric motor converts electrical energy into which form of energy?

  1. Chemical energy
  2. Sound energy only
  3. Light energy
  4. Kinetic energy Correct answer.

Explanation

A motor uses the force on a current-carrying coil in a magnetic field to produce rotation, so electrical energy becomes kinetic energy. Some energy is also lost as heat in the coil and as sound. Generators do the reverse, converting kinetic energy into electrical energy.

Question 15Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A household circuit has a 10 A fuse protecting a 230 V supply. What is the maximum power the circuit can safely deliver?

  1. 23 W
  2. 2300 W Correct answer.
  3. 0.043 W
  4. 240 W

Explanation

Electrical power is P = VI, so 230 V × 10 A = 2300 W. This is the maximum power the fuse will allow before it melts. Appliances with a combined power above this would blow the fuse.

Question 16Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Why is electrical energy transmitted at very high voltages through the national grid?

  1. High voltage increases the resistance of the transmission lines
  2. High voltage reduces the current, so less energy is wasted as heat in the cables Correct answer.
  3. High voltage converts the current into a magnetic field for storage
  4. High voltage makes the cables lighter and easier to support

Explanation

For a given power, P = VI, so raising the voltage lowers the current. Since power lost in cables is I²R, a smaller current means much less energy is wasted as heat. Transformers raise the voltage for transmission and lower it again for use in homes.

Question 17Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student wants to make an electromagnet stronger without changing the core. Which pair of changes would both increase its strength?

  1. Decrease the current and increase the number of turns
  2. Increase the current and increase the number of turns Correct answer.
  3. Increase the current and reverse the battery polarity
  4. Decrease the current and decrease the number of turns

Explanation

The magnetic field of a coil increases with both the current through the wire and the number of turns. Increasing either one strengthens the electromagnet, so increasing both gives the greatest gain. Reversing polarity only changes the direction of the field.

Question 18Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which of these devices relies on the magnetic effect of a current to operate?

  1. A loudspeaker Correct answer.
  2. A filament lamp
  3. An electric kettle
  4. A resistor

Explanation

A loudspeaker uses the force on a current-carrying coil in a permanent magnetic field to move a cone and produce sound. This is the motor effect, a magnetic effect of current. Kettles and lamps rely on the heating effect, while resistors simply oppose current.

Question 19Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

In a parallel circuit, one of three identical branches is disconnected. What happens to the total resistance of the circuit?

  1. It becomes zero
  2. It increases Correct answer.
  3. It decreases
  4. It stays the same

Explanation

Adding parallel branches provides more paths for current, lowering total resistance; removing a branch therefore increases it. With one branch removed, there are fewer parallel paths, so the total resistance rises. The current drawn from the supply correspondingly falls.

Question 20Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

What is the function of a diode in a simple circuit?

  1. It converts electrical energy into light
  2. It stores charge like a battery
  3. It increases the voltage of the supply
  4. It allows current to flow in one direction only Correct answer.

Explanation

A diode is a semiconductor device that conducts readily in one direction and blocks current in the reverse direction. This property is used in rectification to convert alternating current into direct current. It does not amplify or store charge.

Question 21Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A 60 W lamp is left on for 5.0 hours. How much energy does it use?

  1. 12 J
  2. 1.08 × 10³ J
  3. 1.08 × 10⁶ J Correct answer.
  4. 300 J

Explanation

Energy is power multiplied by time, with time in seconds. Five hours is 18 000 s, so E = 60 × 18 000 = 1.08 × 10⁶ J. This is equivalent to 0.30 kWh, since 60 W × 5 h = 300 Wh.

Question 22Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which statement best explains why the current in a series circuit is the same at every point?

  1. The voltage is the same across every component
  2. Charge is used up as it passes through each component
  3. Each component has a different resistance that equalises the current
  4. Charge cannot accumulate at any point, so the same rate of charge flow passes each point Correct answer.

Explanation

In a series circuit there is only one path, and charge is conserved, so the rate of flow (current) must be identical everywhere. Charge does not build up at components. The voltage, however, is shared between components in proportion to their resistance.

Question 23Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which change would decrease the resistance of a metal wire?

  1. Increasing its cross-sectional area Correct answer.
  2. Using a material with higher resistivity
  3. Increasing its temperature
  4. Increasing its length

Explanation

Resistance is inversely proportional to cross-sectional area, so a thicker wire has lower resistance. This is because a wider wire offers more paths for charge carriers. Length, temperature and resistivity all increase resistance when increased.

Question 24Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A transformer is used to step down a 230 V supply to 11.5 V for a device. If the primary coil has 800 turns, how many turns does the secondary coil have?

  1. 400
  2. 16 000
  3. 40 Correct answer.
  4. 80

Explanation

For an ideal transformer, the turns ratio equals the voltage ratio: Ns/Np = Vs/Vp. Here 11.5/230 = 0.05, so Ns = 0.05 × 800 = 40 turns. A step-down transformer always has fewer secondary turns than primary turns.

Question 25Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which safety feature in a modern New Zealand home is designed to cut power quickly when current leaks to earth through a person?

  1. A step-up transformer
  2. A light-emitting diode
  3. A fuse in the appliance plug
  4. A residual current device (RCD) Correct answer.

Explanation

An RCD monitors the difference between live and neutral currents and trips when a small leakage to earth is detected. This protects people from electric shock, unlike a fuse which mainly protects wiring from overheating. RCDs respond to much smaller currents than fuses.

Question 26Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student builds a simple circuit with a battery, a switch, and a lamp. The switch is closed and the lamp lights. Which statement describes the energy transformation that occurs while the lamp is lit?

  1. Electrical energy in the wires is converted to chemical energy in the lamp filament.
  2. Light energy in the lamp is converted to electrical energy, then stored as chemical energy in the battery.
  3. Heat energy in the surroundings is converted to electrical energy in the battery.
  4. Chemical energy in the battery is converted to electrical energy, then to light and heat in the lamp. Correct answer.

Explanation

A battery stores chemical energy and converts it to electrical energy, which is carried by the circuit. The lamp filament then converts electrical energy into light and heat. Energy is transferred through the circuit rather than created, so the chain of transformations runs from chemical to electrical to light and heat.

Question 27Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student investigates how the current through a fixed resistor changes as the voltage across it increases. The results give a straight-line graph passing through the origin. What does this show about the resistor?

  1. Its resistance stays constant as the voltage changes. Correct answer.
  2. Its resistance decreases as the voltage increases.
  3. Its resistance increases as the voltage increases.
  4. Its resistance becomes zero at high voltages.

Explanation

For a fixed resistor, current is proportional to voltage, so the graph of current against voltage is a straight line through the origin. The gradient of that line equals one divided by the resistance, and a constant gradient means constant resistance. This is the relationship described by Ohm's law for an ohmic component.

Question 28Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

In a New Zealand home, the live and neutral wires of a power supply are described. Which statement correctly describes the potential difference between the live wire and earth?

  1. Both the live and neutral wires are at 0 V relative to earth at all times.
  2. The live wire is near 0 V relative to earth, while the neutral wire is at about 230 V.
  3. The live wire is at about 230 V relative to earth, while the neutral wire is near 0 V. Correct answer.
  4. Both the live and neutral wires are at about 230 V relative to earth.

Explanation

Mains supply in New Zealand is about 230 V, and the neutral wire is connected to earth at the supply point, so it sits close to earth potential. The live wire alternates about 230 V relative to earth. This is why touching the live wire is dangerous while touching a properly connected neutral is normally much safer.

Question 29Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student uses a current-carrying solenoid and places a compass needle near one end. The student reverses the direction of the current. What happens to the magnetic field of the solenoid?

  1. It disappears completely while the current flows.
  2. Its direction reverses, but its strength stays the same. Correct answer.
  3. Its strength halves and its direction reverses.
  4. Its strength doubles while its direction stays the same.

Explanation

The magnetic field of a solenoid depends on the current direction, so reversing the current reverses the field direction. The size of the current is unchanged, so the field strength is unchanged. This is why the ends of an electromagnet swap between north and south poles when the current is reversed.

Question 30Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A 12 V car battery supplies a current of 4.0 A to a headlamp. What is the resistance of the lamp?

  1. 3.0 Ω Correct answer.
  2. 48 Ω
  3. 0.33 Ω
  4. 16 Ω

Explanation

Resistance is found from R = V/I. Substituting gives R = 12 V ÷ 4.0 A = 3.0 Ω. The other values come from multiplying instead of dividing, or from inverting the calculation incorrectly.

Question 31Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A power station generates 100 MW of electrical power. It is transmitted through cables at 200 kV. Why is a high transmission voltage used instead of a low one?

  1. A higher voltage allows the cables to store energy for later use by consumers.
  2. For the same power, a higher voltage means a smaller current, so less energy is wasted as heat in the cables. Correct answer.
  3. A higher voltage makes the cables carry more current, which reduces the resistance of the cables.
  4. A higher voltage increases the resistance of the cables, which protects the transmission system.

Explanation

Power transmitted equals voltage multiplied by current. Raising the voltage for a fixed power reduces the current, and heating in cables depends on the square of the current. A smaller current therefore means much less energy lost as heat in the transmission lines.

Question 32Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A household appliance is rated at 230 V and 2.0 kW. What current does it draw when operating normally?

  1. 460 A
  2. 0.12 A
  3. 8.7 A Correct answer.
  4. 115 A

Explanation

Power equals voltage multiplied by current, so current equals power divided by voltage. Converting 2.0 kW to 2000 W gives I = 2000 W ÷ 230 V ≈ 8.7 A. A fuse or circuit breaker for this appliance would need a rating above this value.

Question 33Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student wraps insulated wire around an iron nail and connects it to a battery. The nail picks up paper clips. The student then adds more turns of wire while keeping the current the same. What is the expected effect?

  1. The electromagnet becomes stronger and can pick up more paper clips. Correct answer.
  2. The electromagnet becomes weaker because each turn shares the current.
  3. The electromagnet strength stays exactly the same because the current is unchanged.
  4. The electromagnet reverses its polarity and repels the paper clips.

Explanation

The strength of an electromagnet increases with the number of turns of wire in the coil. More turns with the same current produce a stronger magnetic field around the iron core. The iron core concentrates the field, so the nail lifts more paper clips.

Question 34Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student connects three identical resistors in a circuit. Two are in parallel with each other, and this pair is in series with the third. Each resistor has resistance R. What is the total resistance of the circuit?

  1. 1.5R Correct answer.
  2. 3R
  3. 0.67R
  4. 2R

Explanation

Two identical resistors in parallel have a combined resistance of R/2. This combination is in series with the third resistor, so the total is R + R/2 = 1.5R. Parallel branches always give a smaller combined resistance than a single branch.

Question 35Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which statement correctly describes the magnetic field pattern around a straight wire carrying a steady current?

  1. The field runs parallel to the wire, pointing in the direction of the current.
  2. The field exists only at the two ends of the wire.
  3. The field forms concentric circles around the wire, with direction given by the right-hand grip rule. Correct answer.
  4. The field points straight outward from the wire in all directions like a bar magnet.

Explanation

A current-carrying wire produces a magnetic field made of circles centred on the wire. The direction of these circles is found with the right-hand grip rule: thumb along the current, fingers curl in the field direction. The field strength decreases with distance from the wire.

Question 36Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student wants to reduce the energy used by a household appliance without changing how long it is used. Which change would reduce the energy consumed?

  1. Increasing the voltage supplied to the appliance
  2. Replacing the appliance with one that has a lower power rating Correct answer.
  3. Using thicker connecting wires to the appliance
  4. Using the appliance at a different time of day

Explanation

Energy used equals power multiplied by time. If the operating time is fixed, a lower power rating means less energy is consumed. Power ratings are quoted on appliance labels and are the basis of energy efficiency comparisons.

Question 37Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A circuit contains a battery, a resistor, and an ammeter in series. A student wants to measure the voltage across the resistor. How should a voltmeter be connected?

  1. In series with the resistor
  2. In series with the ammeter
  3. In place of the battery
  4. In parallel with the resistor Correct answer.

Explanation

A voltmeter measures the potential difference between two points, so it is connected across the component in parallel. It has a very high resistance so that it draws almost no current. An ammeter, by contrast, is connected in series to measure current.

Question 38Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student builds a circuit with a light-dependent resistor (LDR) in series with a fixed resistor and a battery. The voltage across the fixed resistor is used as a signal. As light intensity on the LDR increases, its resistance falls. What happens to the voltage across the fixed resistor?

  1. It decreases, because the LDR takes a larger share of the voltage.
  2. It stays the same, because the battery voltage is constant.
  3. It increases, because the total circuit resistance falls and the current rises. Correct answer.
  4. It falls to zero, because the LDR becomes a short circuit in bright light.

Explanation

When light increases, LDR resistance falls, so total circuit resistance falls and current rises. The voltage across the fixed resistor equals current times its resistance, so it increases. This changing voltage is used as a signal in light-sensing circuits.

Question 39Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A fuse in a plug is rated at 3 A. An appliance drawing 5 A is connected using this fuse. What is the expected result?

  1. The fuse will allow the appliance to run normally because it has a higher resistance.
  2. The fuse will reduce the current to 3 A and the appliance will run more slowly.
  3. The fuse will melt and break the circuit because the current exceeds its rating. Correct answer.
  4. The fuse will reverse the current direction to protect the appliance.

Explanation

A fuse is designed to melt when the current exceeds its rating, breaking the circuit. A 5 A current through a 3 A fuse exceeds the rating, so the fuse element overheats and melts. This protects the wiring and appliance from excessive current.

Question 40Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student compares two wires of the same material and length, but one has twice the cross-sectional area of the other. How does the resistance of the thicker wire compare with the thinner wire?

  1. It is four times as much.
  2. It is twice as much.
  3. It is half as much. Correct answer.
  4. It is the same.

Explanation

Resistance is inversely proportional to cross-sectional area for a given material and length. Doubling the area doubles the number of paths for charge carriers, so the resistance halves. This is why thick cables are used for high currents.

Question 41Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student measures the current in a simple series circuit containing a battery, a switch, and two lamps. Where in the circuit will the ammeter read the largest current?

  1. Between the battery and the first lamp
  2. Between the two lamps
  3. The current is the same at every point in the series circuit. Correct answer.
  4. Between the second lamp and the battery

Explanation

In a series circuit there is only one path for charge to flow, so the current is the same at every point. Charge is not used up as it passes through components. The ammeter will read the same value wherever it is placed in the single loop.

Question 42Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student uses a transformer with 500 turns on the primary and 25 turns on the secondary. The primary is connected to a 230 V supply. Assuming an ideal transformer, what is the secondary voltage?

  1. 4600 V
  2. 23 V
  3. 0.087 V
  4. 11.5 V Correct answer.

Explanation

For an ideal transformer the voltage ratio equals the turns ratio: Vs/Vp = Ns/Np. Substituting gives Vs = 230 V × (25/500) = 11.5 V. This is a step-down transformer because the secondary has fewer turns.

Question 43Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student is asked to explain why the metal case of a class I appliance is earthed. Which explanation is most accurate?

  1. If a fault connects the live wire to the case, current flows to earth and the fuse or breaker operates quickly. Correct answer.
  2. Earthing increases the resistance of the appliance so less current flows.
  3. Earthing stores excess charge in the case to prevent sparks.
  4. Earthing makes the case carry the neutral current during normal operation.

Explanation

Earthing provides a low-resistance path from the metal case to earth. If a fault makes the case live, a large current flows to earth and quickly operates the fuse or circuit breaker. This removes the danger before a person can receive a serious shock.

Question 44Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student wants to demonstrate that a changing magnetic field can produce a current in a wire. Which setup is most suitable?

  1. Connecting a coil to a battery and placing a compass nearby
  2. Holding a magnet still next to a coil connected to a battery
  3. Moving a magnet in and out of a coil connected to a galvanometer Correct answer.
  4. Placing a bar magnet next to a piece of unmagnetised iron

Explanation

Electromagnetic induction occurs when the magnetic field through a coil changes, producing an induced voltage. Moving a magnet in and out of a coil changes the field through the coil, so a current is induced and the galvanometer deflects. A stationary magnet produces no change and therefore no induced current.

Question 45Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student measures the current through a filament lamp at several voltages and plots the results. The graph curves so that the gradient decreases at higher voltages. What does this show?

  1. The filament stops conducting at high voltages.
  2. The resistance of the filament decreases as it gets hotter.
  3. The resistance of the filament increases as it gets hotter. Correct answer.
  4. The resistance of the filament stays constant at all voltages.

Explanation

For a filament lamp, current rises less quickly at higher voltages, so the resistance increases. The filament gets hotter as more current flows, and higher temperature increases the resistance of the metal. This non-ohmic behaviour is why the graph curves rather than staying straight.

Question 46Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

Which of these describes the function of a circuit breaker in a household distribution board?

  1. It automatically opens the circuit when the current exceeds a set value and can be reset. Correct answer.
  2. It reduces the voltage supplied to appliances to a safer level.
  3. It converts alternating current into direct current for appliances.
  4. It melts permanently when the current is too high and must be replaced.

Explanation

A circuit breaker is an automatic switch that opens when the current exceeds its rating. Unlike a fuse, it does not melt and can be reset after the fault is fixed. It protects wiring from overheating and fire.

Question 47Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student connects a 6.0 V battery across two resistors in series, 4.0 Ω and 8.0 Ω. What is the voltage across the 8.0 Ω resistor?

  1. 8.0 V
  2. 6.0 V
  3. 4.0 V Correct answer.
  4. 2.0 V

Explanation

The total resistance is 12 Ω, so the current is 6.0 V ÷ 12 Ω = 0.50 A. The voltage across the 8.0 Ω resistor is then 0.50 A × 8.0 Ω = 4.0 V. The larger resistor takes the larger share of the supply voltage.

Question 48Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student is comparing the energy use of two lamps. Lamp A is rated 20 W and runs for 10 hours. Lamp B is rated 100 W and runs for 2 hours. Which lamp uses more energy?

  1. Lamp B, which uses 200 Wh compared with 20 Wh for Lamp A
  2. They use the same energy, 200 Wh each Correct answer.
  3. Lamp A, which uses 200 Wh compared with 200 Wh for Lamp B
  4. Lamp B, which uses 200 Wh compared with 200 Wh for Lamp A

Explanation

Energy equals power multiplied by time. Lamp A uses 20 W × 10 h = 200 Wh, and Lamp B uses 100 W × 2 h = 200 Wh. Both lamps therefore use the same amount of energy despite their different power ratings and operating times.

Question 49Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

A student wants to make an electromagnet that can be switched on and off quickly and whose strength can be varied. Which design is most suitable?

  1. A coil of wire around a plastic core, connected directly to a battery with no switch
  2. A coil of insulated wire around an iron core, connected through a variable resistor and a switch Correct answer.
  3. A single straight wire connected to a battery
  4. A permanent bar magnet mounted on a wooden handle

Explanation

An electromagnet uses a current-carrying coil with an iron core to produce a strong magnetic field. A switch allows it to be turned on and off, and a variable resistor allows the current, and therefore the strength, to be adjusted. A permanent magnet cannot be switched off.

Question 50Science (achievement standards covering specific sets of skills and knowledge, e.g. investigating implications of electricity and magnetism for everyday life)

In a parallel circuit, two identical lamps are connected across a battery. One lamp is removed. What happens to the brightness of the remaining lamp?

  1. It goes out because the circuit is broken.
  2. It becomes dimmer because the total resistance increases.
  3. It becomes brighter because it now receives all the current.
  4. It stays the same because it still receives the full battery voltage. Correct answer.

Explanation

In a parallel circuit each branch is connected directly across the supply, so each lamp receives the full battery voltage regardless of the other branch. Removing one lamp does not change the voltage across the remaining one. Its brightness therefore stays the same.