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Assam ASSEB HSLC NSQF Electronics and Hardware study materials
Assam ASSEB HSLC NSQF Electronics and Hardware study resources

Assam ASSEB HSLC NSQF Electronics and Hardware practice questions

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Question 1Basic Electrical and Electronic Fundamentals

In an electrical circuit, what is the standard unit of electric current?

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

Explanation

Electric current is the rate of flow of electric charge and its SI unit is the ampere, defined as one coulomb of charge passing a point per second. The other units measure different quantities, so only the ampere describes current itself.

Question 2Basic Electrical and Electronic Fundamentals

Which material is classified as a good conductor of electricity in hardware work?

  1. Bakelite
  2. Copper Correct answer.
  3. Dry wood
  4. Rubber

Explanation

Copper has many free electrons that move easily under an applied voltage, so it conducts current well and is widely used for wires and PCB tracks. Rubber, dry wood and Bakelite lack free charge carriers and behave as insulators.

Question 3Basic Electrical and Electronic Fundamentals

A resistor of 220 ohm carries a current of 0.05 A. What is the voltage across it?

  1. 0.22 V
  2. 4.4 V
  3. 11 V Correct answer.
  4. 4400 V

Explanation

Ohm's law states V = I x R, so multiplying 0.05 A by 220 ohm gives 11 V. The other values come from dividing or misplacing the decimal point instead of multiplying current by resistance.

Question 4Basic Electrical and Electronic Fundamentals

Two 100 ohm resistors are connected in series. What is the total resistance of the combination?

  1. 10 ohm
  2. 50 ohm
  3. 200 ohm Correct answer.
  4. 100 ohm

Explanation

In a series connection the same current flows through each resistor and the total resistance is the sum of the individual values, giving 100 + 100 = 200 ohm. The parallel formula would be needed only if both ends of the resistors were joined together.

Question 5Basic Electrical and Electronic Fundamentals

What is the function of a diode in a basic electronic circuit?

  1. To amplify a small signal
  2. To allow current in one direction only Correct answer.
  3. To convert resistance into capacitance
  4. To store charge between two plates

Explanation

A diode is a two-terminal semiconductor device whose p-n junction conducts easily in forward bias and blocks current in reverse bias, so it acts as a one-way valve. This property is used for rectification and for protecting circuits from reverse polarity.

Question 6Basic Electrical and Electronic Fundamentals

Which instrument is connected in parallel with a component to measure the voltage across it?

  1. Ohmmeter
  2. Galvanometer
  3. Ammeter
  4. Voltmeter Correct answer.

Explanation

A voltmeter is placed in parallel so that it experiences the same potential difference as the component, and it is designed with very high resistance to draw negligible current. An ammeter, by contrast, is inserted in series to measure current.

Question 7Basic Electrical and Electronic Fundamentals

In a colour-coded resistor, the colour brown in the first band represents which digit?

  1. 1 Correct answer.
  2. 5
  3. 0
  4. 2

Explanation

The resistor colour code assigns brown the digit 1, following black for 0 and preceding red for 2. The first two bands give the significant figures of the resistance value.

Question 8Basic Electrical and Electronic Fundamentals

What is the purpose of a fuse in an electrical appliance?

  1. To melt and break the circuit when current exceeds a safe value Correct answer.
  2. To increase the voltage supplied to the appliance
  3. To smooth the ripple in a DC supply
  4. To store energy for later use

Explanation

A fuse contains a thin element that heats and melts when the current rises above its rated value, opening the circuit and protecting wiring and components from overheating. It is a deliberate weak link placed in series with the load.

Question 9Basic Electrical and Electronic Fundamentals

A 12 V battery supplies 2 A to a lamp. How much power does the lamp dissipate?

  1. 14 W
  2. 0.17 W
  3. 24 W Correct answer.
  4. 6 W

Explanation

Electrical power is the product of voltage and current, P = V x I, so 12 V multiplied by 2 A gives 24 W. This is the rate at which the lamp converts electrical energy into light and heat.

Question 10Basic Electrical and Electronic Fundamentals

Three resistors of 6 ohm each are connected in parallel. What is the equivalent resistance?

  1. 3 ohm
  2. 6 ohm
  3. 18 ohm
  4. 2 ohm Correct answer.

Explanation

For identical resistors in parallel the equivalent resistance equals one value divided by the number of branches, so 6 divided by 3 gives 2 ohm. The reciprocal formula 1/R = 1/6 + 1/6 + 1/6 confirms this result.

Question 11Basic Electrical and Electronic Fundamentals

A silicon diode is forward biased in a circuit. Which statement describes its behaviour?

  1. It behaves as a perfect insulator at all voltages
  2. It always drops exactly 5 V when conducting
  3. It conducts heavily in reverse bias
  4. It conducts once the applied voltage exceeds about 0.7 V Correct answer.

Explanation

A forward-biased silicon p-n junction needs roughly 0.7 V to overcome the barrier potential, after which current rises steeply with small further increases in voltage. Germanium diodes show a lower knee voltage of about 0.3 V.

Question 12Basic Electrical and Electronic Fundamentals

What is the main function of a capacitor in an electronic circuit?

  1. To store electrical energy in an electric field Correct answer.
  2. To rectify alternating current
  3. To provide a fixed voltage reference
  4. To store energy in a magnetic field

Explanation

A capacitor consists of two conductors separated by a dielectric and stores charge, and therefore energy, in the electric field between its plates. Its ability to charge and discharge makes it useful for coupling, filtering and timing.

Question 13Basic Electrical and Electronic Fundamentals

Which type of transformer is used to step down the 230 V mains to a low AC voltage for a power supply?

  1. A transformer with equal turns on both windings
  2. A transformer with more turns on the primary than on the secondary Correct answer.
  3. A transformer with more turns on the secondary than on the primary
  4. A transformer with a single winding only

Explanation

The secondary voltage of a transformer is proportional to the turns ratio, so a step-down transformer has fewer turns on the secondary than on the primary. For example, a 10:1 turns ratio reduces 230 V to about 23 V.

Question 14Basic Electrical and Electronic Fundamentals

What does the abbreviation PCB stand for in hardware assembly?

  1. Primary Copper Bus
  2. Power Control Block
  3. Parallel Connection Bridge
  4. Printed Circuit Board Correct answer.

Explanation

A PCB is a printed circuit board, an insulating board with copper tracks that connect mounted components in place of hand wiring. It provides mechanical support as well as the electrical interconnections of a circuit.

Question 15Basic Electrical and Electronic Fundamentals

In a half-wave rectifier using one diode, what fraction of the input AC cycle appears at the output?

  1. One half of each cycle Correct answer.
  2. The complete cycle
  3. One quarter of each cycle
  4. No part of the cycle

Explanation

A single diode conducts only during the half cycle in which it is forward biased, so the output contains one pulse per input cycle and the other half is blocked. This gives a pulsating DC with a low average value and high ripple.

Question 16Basic Electrical and Electronic Fundamentals

A resistor has bands brown, black, red and gold. What is its nominal value and tolerance?

  1. 100 ohm, plus or minus 5 percent
  2. 1 kohm, plus or minus 5 percent Correct answer.
  3. 10 kohm, plus or minus 10 percent
  4. 1 kohm, plus or minus 1 percent

Explanation

Brown and black give the digits 1 and 0, the red multiplier adds two zeros giving 1000 ohm or 1 kohm, and gold indicates a tolerance of plus or minus 5 percent. Reading the multiplier band as a digit instead of a power of ten is a common error.

Question 17Basic Electrical and Electronic Fundamentals

Why is a zener diode operated in reverse breakdown in a voltage regulator?

  1. It becomes a perfect conductor with zero voltage drop
  2. Its voltage stays nearly constant over a range of reverse current Correct answer.
  3. It stores charge like a capacitor
  4. It then conducts in only one direction

Explanation

Beyond the zener knee the reverse voltage across the diode changes very little even as the current varies widely, so it can hold a steady reference across a load. A series resistor limits the current to keep the diode within its rated dissipation.

Question 18Basic Electrical and Electronic Fundamentals

A circuit draws 0.5 A from a 12 V supply. What is the total resistance of the circuit?

  1. 12.5 ohm
  2. 0.04 ohm
  3. 6 ohm
  4. 24 ohm Correct answer.

Explanation

Rearranging Ohm's law gives R = V / I, so 12 V divided by 0.5 A equals 24 ohm. This single equivalent resistance represents the combined effect of all components in the circuit.

Question 19Basic Electrical and Electronic Fundamentals

What happens to the total resistance when an extra resistor is added in parallel to an existing parallel network?

  1. The total resistance stays the same
  2. The total resistance increases
  3. The total resistance decreases Correct answer.
  4. The total resistance becomes zero

Explanation

Adding a parallel branch provides an extra path for current, so the overall conductance rises and the equivalent resistance falls below the smallest branch value. This is why household appliances are wired in parallel and each can draw current independently.

Question 20Basic Electrical and Electronic Fundamentals

Which statement correctly distinguishes AC from DC?

  1. AC periodically reverses direction, while DC flows in one direction Correct answer.
  2. DC is produced only by generators and AC only by batteries
  3. Both AC and DC reverse direction at 50 Hz
  4. AC flows in one direction, while DC reverses periodically

Explanation

Alternating current changes polarity periodically, as supplied by mains at 50 Hz in India, whereas direct current maintains a constant polarity as from a battery or rectified supply. The frequency of AC describes how many complete cycles occur each second.

Question 21Basic Electrical and Electronic Fundamentals

A 1 kohm resistor is connected across a 9 V battery. What current flows, and what power is dissipated?

  1. 90 mA and 810 mW
  2. 1 mA and 9 mW
  3. 9 mA and 81 mW Correct answer.
  4. 9 A and 81 W

Explanation

The current is V/R = 9/1000 = 0.009 A, which is 9 mA, and the power is V x I = 9 x 0.009 = 0.081 W or 81 mW. Both results follow directly from Ohm's law and the power equation.

Question 22Basic Electrical and Electronic Fundamentals

Two resistors of 4 ohm and 6 ohm are in series across a 20 V supply. What is the voltage across the 6 ohm resistor?

  1. 6 V
  2. 8 V
  3. 20 V
  4. 12 V Correct answer.

Explanation

The series current is 20 V divided by the 10 ohm total, giving 2 A, and the drop across 6 ohm is 2 A times 6 ohm, which is 12 V. The voltage divides in proportion to resistance, so the larger resistor takes the larger share.

Question 23Basic Electrical and Electronic Fundamentals

A bridge rectifier is used instead of a centre-tap full-wave rectifier. Which advantage is correct?

  1. It converts AC to DC without any diodes
  2. It produces no ripple at the output
  3. It needs only one diode
  4. It needs no centre-tapped transformer and uses the whole secondary winding Correct answer.

Explanation

A bridge uses four diodes and can take its input directly from an ordinary transformer secondary, using both halves of the winding and giving a higher output for the same transformer. The centre-tap design needs a tapped transformer and only uses half the winding at a time.

Question 24Basic Electrical and Electronic Fundamentals

A current of 2 A flows through a wire of resistance 0.5 ohm. What is the power lost as heat in the wire?

  1. 4 W
  2. 1 W
  3. 0.25 W
  4. 2 W Correct answer.

Explanation

The heating power in a conductor is I squared times R, so 2 squared times 0.5 gives 4 times 0.5, which is 2 W. This expression is used because the voltage drop itself depends on the current, making I squared R the direct route.

Question 25Basic Electrical and Electronic Fundamentals

In a parallel circuit of 10 ohm and 15 ohm across a 30 V supply, what is the total current drawn?

  1. 1.2 A
  2. 5 A Correct answer.
  3. 2 A
  4. 3 A

Explanation

Each branch sees the full 30 V, so the currents are 30/10 = 3 A and 30/15 = 2 A, giving a total of 5 A. Equivalently the parallel resistance is 6 ohm and 30 V divided by 6 ohm is 5 A.

Question 26Basic Electrical and Electronic Fundamentals

Which quantity remains the same for every component connected in a series circuit?

  1. The resistance of each component
  2. The power dissipated in each component
  3. The voltage across each component
  4. The current through each component Correct answer.

Explanation

In a series circuit there is only one path for charge to flow, so the same current passes through every component. The supply voltage divides among the components according to their resistances, so voltage, power and resistance can all differ from one component to the next.

Question 27Basic Electrical and Electronic Fundamentals

An LED indicator in a hardware project must run from a 5 V supply with a forward current of 20 mA. The LED has a forward voltage drop of 2 V. Which series resistor value is required?

  1. 150 ohm Correct answer.
  2. 250 ohm
  3. 350 ohm
  4. 100 ohm

Explanation

The resistor must drop the difference between the supply and the LED forward voltage, that is 5 V minus 2 V equals 3 V. Using Ohm's law, R equals V divided by I, so 3 V divided by 0.02 A gives 150 ohm. This value sets the current at the intended 20 mA.

Question 28Basic Electrical and Electronic Fundamentals

Which material property makes copper a preferred conductor for wiring in electronic hardware?

  1. It has a low resistivity, so it offers little resistance to current Correct answer.
  2. It has almost no free electrons in its lattice
  3. It has a high resistivity, so it limits current safely
  4. It has a very wide forbidden energy gap

Explanation

Conductors such as copper have many free electrons and a low resistivity, so a wire of practical size carries current with only a small voltage drop and little heating. High resistivity and a wide forbidden gap describe insulators or semiconductors, not wiring conductors.

Question 29Basic Electrical and Electronic Fundamentals

A coil of wire is moved steadily past a stationary magnet in a closed circuit. What happens in the coil?

  1. No EMF appears because the magnet itself is not moving
  2. An EMF is induced in it because the magnetic flux linking it changes Correct answer.
  3. A steady DC current flows with no induced EMF
  4. Its resistance falls, so the current rises without any EMF

Explanation

Faraday's law states that an EMF is induced whenever the magnetic flux linking a circuit changes, and relative motion between coil and magnet produces exactly such a change. Only relative motion matters, so a moving coil past a fixed magnet induces an EMF just as a moving magnet past a fixed coil does.

Question 30Basic Electrical and Electronic Fundamentals

A silicon transistor in a switching circuit is to be driven fully into saturation. Which base-emitter condition achieves this?

  1. The base-emitter junction is reverse biased so that no base current flows
  2. The base-emitter junction is forward biased with a base current far below the collector current divided by hFE
  3. The base-emitter junction is left open so that the base floats
  4. The base-emitter junction is forward biased with enough base current to exceed the collector current divided by hFE Correct answer.

Explanation

Saturation requires the base current to be at least the collector current divided by the transistor's current gain hFE, so that the collector-emitter voltage falls to a small value and the device behaves almost like a closed switch. Merely forward biasing the junction is not enough; the base current must be adequate for the collector load.

Question 31Electronic Components and Identification

A resistor is marked with the colour bands brown, black, red, gold. What is its resistance and tolerance?

  1. 100 Ω with ±5% tolerance
  2. 10 Ω with ±5% tolerance
  3. 1 kΩ with ±5% tolerance Correct answer.
  4. 1 kΩ with ±10% tolerance

Explanation

In the four-band code the first two bands give significant digits (brown = 1, black = 0), the third band gives the multiplier (red = ×100) and the fourth gives tolerance (gold = ±5%). So the value is 10 × 100 = 1000 Ω, i.e. 1 kΩ at ±5%.

Question 32Electronic Components and Identification

Which component stores energy in an electric field between two conducting plates separated by a dielectric?

  1. Capacitor Correct answer.
  2. Diode
  3. Resistor
  4. Inductor

Explanation

A capacitor consists of two conducting plates separated by an insulating dielectric; when charged, energy is stored in the electric field between the plates. An inductor instead stores energy in a magnetic field around a coil, a resistor dissipates energy as heat, and a diode is a one-way junction device.

Question 33Electronic Components and Identification

A capacitor is marked 474K. What is its nominal capacitance?

  1. 47 pF
  2. 4.7 µF
  3. 47 nF
  4. 470 nF Correct answer.

Explanation

In the three-digit capacitor code the first two digits are significant figures and the third is the number of trailing zeros in picofarads. Thus 474 means 47 followed by four zeros = 470000 pF = 470 nF = 0.47 µF, and the letter K indicates ±10% tolerance.

Question 34Electronic Components and Identification

What does the third band of a four-band resistor colour code represent?

  1. The temperature coefficient
  2. The multiplier (number of zeros) Correct answer.
  3. The power rating
  4. The tolerance of the resistor

Explanation

In the four-band code the first two bands give the significant digits, the third band gives the multiplier (power of ten applied to those digits), and the fourth band gives tolerance. The multiplier band is therefore the one that fixes the order of magnitude of the value.

Question 35Electronic Components and Identification

Which property of a diode is being tested when a multimeter in diode-test mode shows about 0.6 V in one direction and OL in the reverse direction?

  1. That the diode is a zener diode in breakdown
  2. That the diode is forward-biased and healthy in that direction Correct answer.
  3. That the diode is short-circuited
  4. That the diode has infinite forward resistance

Explanation

In diode-test mode the meter applies a small voltage and displays the forward voltage drop. A silicon diode reads roughly 0.6–0.7 V when forward-biased and shows OL (out of range, very high resistance) when reverse-biased, which is the signature of a good diode.

Question 36Electronic Components and Identification

Which component is identified by the symbol of a coil with a magnetic core line and is used to oppose changes in current?

  1. Varactor
  2. Thermistor
  3. Photodiode
  4. Inductor Correct answer.

Explanation

An inductor is a coil that stores energy in a magnetic field and opposes any change in the current through it, since a changing current induces a back-emf. The other listed devices are special semiconductor or resistive components with different functions.

Question 37Electronic Components and Identification

A resistor has bands orange, orange, orange, silver. What is its resistance range?

  1. 18 kΩ to 22 kΩ
  2. 33 kΩ to 33 kΩ
  3. 29.7 kΩ to 36.3 kΩ Correct answer.
  4. 30 kΩ to 36 kΩ

Explanation

Orange-orange-orange gives 33 × 1000 = 33 kΩ, and silver in the fourth band means ±10% tolerance. Ten percent of 33 kΩ is 3.3 kΩ, so the acceptable range is 29.7 kΩ to 36.3 kΩ.

Question 38Electronic Components and Identification

What is the primary function of a fuse in an electronic circuit?

  1. To store charge for later release
  2. To amplify the signal voltage
  3. To melt and open the circuit on excessive current Correct answer.
  4. To rectify alternating current into direct current

Explanation

A fuse contains a thin element that melts when the current exceeds its rated value, thereby opening the circuit and protecting components from overcurrent damage. It is a sacrificial protective device, not a signal-processing component.

Question 39Electronic Components and Identification

A seven-segment display module is marked as common-cathode. How must it be driven to light a segment?

  1. Apply a logic low to the segment pin while the common pin is at +5 V
  2. Apply a logic low to the segment pin while the common pin is grounded
  3. Apply a logic high to the segment pin while the common pin is at ground Correct answer.
  4. Apply an alternating voltage between the segment pin and the common pin

Explanation

In a common-cathode display all cathodes are tied together and normally grounded, so a segment lights when its anode pin is taken to a positive voltage through a current-limiting resistor. A logic high forward-biases that segment's LED.

Question 40Electronic Components and Identification

Which package marking style uses a small dot or notch to indicate the orientation of pin 1 on an integrated circuit?

  1. Pin 1 indicator Correct answer.
  2. Date code
  3. Tolerance letter suffix
  4. Colour band code

Explanation

DIP and many other IC packages carry a dot, dimple or notch near pin 1 so that the device is inserted with the correct orientation. Counting then proceeds anticlockwise around the package from that marker.

Question 41Electronic Components and Identification

A light-emitting diode has a forward voltage of 2 V and is to run at 20 mA from a 5 V supply. What series resistor is required?

  1. 150 Ω Correct answer.
  2. 250 Ω
  3. 10 Ω
  4. 100 Ω

Explanation

The resistor must drop the difference between the supply and the LED forward voltage: 5 V − 2 V = 3 V. Using Ohm's law, R = V/I = 3 V / 0.02 A = 150 Ω, which limits the current to the desired 20 mA.

Question 42Electronic Components and Identification

What does the tolerance band on a resistor indicate?

  1. The voltage the resistor can withstand continuously
  2. The maximum power the resistor can dissipate
  3. The maximum percentage by which the actual resistance may differ from the marked value Correct answer.
  4. The temperature at which the resistor fails

Explanation

The tolerance band states the permitted deviation of the actual resistance from the nominal marked value, expressed as a percentage. For example, a gold band means the true value lies within ±5% of the coded resistance.

Question 43Electronic Components and Identification

A capacitor is marked 105. What value does this represent?

  1. 10 µF
  2. 1 µF Correct answer.
  3. 0.1 µF
  4. 100 nF

Explanation

The code 105 means 10 followed by five zeros in picofarads: 10 × 10^5 pF = 1 000 000 pF = 1 µF. The first two digits are significant figures and the third is the multiplier.

Question 44Electronic Components and Identification

Which statement correctly describes the difference between a fixed and a variable resistor?

  1. A fixed resistor has a set resistance, while a variable resistor allows adjustment of its resistance Correct answer.
  2. A fixed resistor can only carry direct current, while a variable resistor handles alternating current
  3. A fixed resistor has no tolerance, while a variable resistor has infinite tolerance
  4. A fixed resistor stores charge, while a variable resistor dissipates it

Explanation

A fixed resistor has a resistance set during manufacture and marked by its colour code, whereas a variable resistor such as a potentiometer or preset allows the resistance to be changed by moving a wiper. Both obey Ohm's law and both have tolerances.

Question 45Electronic Components and Identification

A transistor is marked BC547. What type of device is it?

  1. An NPN bipolar junction transistor Correct answer.
  2. A zener diode
  3. An N-channel junction field-effect transistor
  4. A PNP bipolar junction transistor

Explanation

The BC547 is a widely used small-signal NPN bipolar junction transistor in a TO-92 package. Its complementary partner, the BC557, is the PNP version.

Question 46Electronic Components and Identification

What does the black band on a diode body, or the stripe on a cylindrical package, normally indicate?

  1. The maximum current rating
  2. The forward voltage drop
  3. The cathode terminal Correct answer.
  4. The anode terminal

Explanation

On common axial diodes the coloured band marks the cathode end, so the opposite lead is the anode. This orientation mark tells the assembler which way to insert the diode so that it is correctly biased.

Question 47Electronic Components and Identification

A resistor colour code reads green, blue, brown, gold. What is the resistance?

  1. 5.6 Ω
  2. 56 Ω
  3. 5.6 kΩ
  4. 560 Ω Correct answer.

Explanation

Green = 5 and blue = 6 give the digits 56, brown = ×10 and gold = ±5%. Therefore the value is 56 × 10 = 560 Ω with ±5% tolerance.

Question 48Electronic Components and Identification

Which instrument setting is most appropriate for quickly checking whether a track on a printed circuit board is continuous?

  1. Oscilloscope time-base setting
  2. Continuity mode of a multimeter Correct answer.
  3. Capacitance mode of an LCR meter
  4. Signal generator output level

Explanation

Continuity mode applies a small voltage and gives an audible or visual indication when resistance is very low, which is ideal for checking that a PCB track is unbroken. An LCR meter, oscilloscope or signal generator serves different measurement purposes.

Question 49Electronic Components and Identification

A resistor has bands red, red, red, gold. What is its nominal value with tolerance?

  1. 2.2 kΩ ±5% Correct answer.
  2. 22 Ω ±5%
  3. 220 Ω ±5%
  4. 22 kΩ ±5%

Explanation

Red = 2, so red-red gives the digits 22, and the third red band is a multiplier of ×100. The value is therefore 22 × 100 = 2200 Ω = 2.2 kΩ, with gold giving ±5% tolerance.

Question 50Electronic Components and Identification

Which of these describes the correct way to identify the value of a ceramic disc capacitor marked with the digits 223?

  1. 220 nF
  2. 2.2 nF
  3. 22 pF
  4. 22 nF Correct answer.

Explanation

The code 223 means 22 followed by three zeros in picofarads: 22 × 10^3 pF = 22 000 pF = 22 nF. The third digit is the multiplier, not part of the significant figures.