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Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF study materials
Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF study resources

Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF practice questions

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Question 1Electrical Safety, First Aid and Workplace Practices

A trainee electrician finds a co-worker lying unconscious beside an open distribution board. What should be the first action before touching the casualty?

  1. Pour water on the casualty to revive them
  2. Pull the casualty away by the arm immediately
  3. Run to the store room to fetch a wooden stick
  4. Switch off the supply and isolate the circuit Correct answer.

Explanation

The rescuer must never touch a casualty who may still be in contact with a live conductor, because the rescuer can also be electrocuted. The supply should be switched off and isolated, or the casualty separated using dry insulating material if isolation is impossible. Only after the source is safe should first aid and CPR begin.

Question 2Electrical Safety, First Aid and Workplace Practices

In the colour code for Indian flexible cables, which colour identifies the earth (protective) conductor?

  1. Red
  2. Blue
  3. Black
  4. Green with yellow stripe Correct answer.

Explanation

The protective earth conductor in flexible cords is identified by green insulation with a yellow stripe, a combination reserved only for earthing. Phase and neutral use other colours such as red, yellow, blue, black or brown depending on the cable type. Confusing earth with a live conductor defeats the entire purpose of earthing.

Question 3Electrical Safety, First Aid and Workplace Practices

Which fire extinguisher is appropriate for a fire in an energised electrical panel?

  1. Carbon dioxide extinguisher Correct answer.
  2. Foam extinguisher
  3. Wet chemical extinguisher
  4. Water-type soda acid extinguisher

Explanation

Carbon dioxide is non-conducting and leaves no residue, so it is suitable for live electrical equipment. Water, foam and wet chemical agents conduct electricity and can electrocute the user or spread the fault. The supply should still be isolated as soon as it is safe to do so.

Question 4Electrical Safety, First Aid and Workplace Practices

What is the correct compression rate for chest compressions during CPR on an adult casualty?

  1. 20 to 30 compressions per minute
  2. 40 to 60 compressions per minute
  3. 100 to 120 compressions per minute Correct answer.
  4. 150 to 180 compressions per minute

Explanation

Current resuscitation guidance recommends a compression rate of 100 to 120 per minute with a depth of about 5 to 6 cm for an adult. This rate maintains adequate blood flow to the brain until help arrives. Rates outside this band reduce the effectiveness of circulation.

Question 5Electrical Safety, First Aid and Workplace Practices

Which practice correctly applies the lockout and tagout procedure before maintenance on a motor circuit?

  1. Isolate the breaker, lock it, attach a tag and verify dead with a tester Correct answer.
  2. Switch off the local push button and begin work at once
  3. Inform the supervisor verbally and start work
  4. Ask a co-worker to watch the panel while you work

Explanation

Lockout and tagout requires positive isolation, a personal lock and tag, and verification that the circuit is de-energised before work begins. A local stop button or verbal assurance does not provide a physical guarantee against re-energisation. Verification with a tester confirms the isolation is effective.

Question 6Electrical Safety, First Aid and Workplace Practices

A worker receives a mild electric shock and feels dizzy but has no burns. What is the recommended action?

  1. Apply ointment to the hand and resume work
  2. Take a short rest and say nothing to the supervisor
  3. Stop work, report the incident and get medical examination Correct answer.
  4. Continue working after drinking water

Explanation

Even a mild shock can disturb heart rhythm and cause delayed internal effects, so the worker must stop work, be examined medically and the incident must be recorded. Reporting also triggers investigation of the cause to prevent recurrence. Self-treatment or silence hides a hazard from the whole team.

Question 7Electrical Safety, First Aid and Workplace Practices

Why must a first aider avoid applying butter, oil or ink to an electrical burn?

  1. They react with copper particles in the skin
  2. They cool the burn too quickly
  3. They conduct electricity into the tissue
  4. These substances trap infection and hinder medical assessment Correct answer.

Explanation

Home remedies such as oil, butter or ink contaminate the wound, increase infection risk and obscure the burn from the doctor. The correct first aid is to cool the burn with clean running water and cover it with a sterile non-stick dressing. Only clean water and sterile coverings belong on a burn.

Question 8Electrical Safety, First Aid and Workplace Practices

Which earth resistance value is generally accepted as satisfactory for a domestic earthing pit in Indian practice?

  1. Less than 1 ohm is not required; below 5 to 8 ohm is commonly accepted Correct answer.
  2. Any value, since earth resistance does not affect safety
  3. Between 100 and 200 ohm
  4. Exactly 50 ohm

Explanation

Indian practice generally accepts earth resistance of a few ohms, commonly below 5 to 8 ohm depending on the installation type, measured during dry weather. High earth resistance prevents fault current from tripping protective devices quickly. Earth resistance must therefore be measured periodically and kept low by watering or adding earth pits.

Question 9Electrical Safety, First Aid and Workplace Practices

A worker must work near a live 415 V busbar. Which combination of protective measures is most appropriate?

  1. Cotton gloves, a cotton shirt and a wooden ladder
  2. Insulated tools, rubber gloves, arc-rated clothing and a standby observer Correct answer.
  3. Bare hands with a quick movement to reduce contact time
  4. A single leather glove and normal school shoes

Explanation

Work near live low-voltage equipment requires insulated tools, tested rubber insulating gloves, arc-rated clothing and a second person who can isolate and assist. These measures reduce the chance of contact and protect against arc flash. Ordinary clothing and leather gloves offer no electrical insulation.

Question 10Electrical Safety, First Aid and Workplace Practices

Under the Factories Act provisions applied to electrical work, what is the general rule about working on live conductors?

  1. Live work is prohibited unless it is unavoidable and done with approved safeguards Correct answer.
  2. Live work is allowed only during night shifts
  3. Live work is allowed if the supervisor is informed afterwards
  4. Live work is allowed whenever the worker is experienced

Explanation

The rule is that no work should be done on or near live conductors unless it is unreasonable to make them dead, and then only with suitable protective equipment and precautions. Experience alone is never a substitute for isolation. Informing a supervisor after the act gives no protection at all.

Question 11Electrical Safety, First Aid and Workplace Practices

What is the purpose of a residual current circuit breaker in a workshop socket circuit?

  1. It converts alternating current into direct current
  2. It trips on small earth leakage currents to protect people from shock Correct answer.
  3. It improves the power factor of induction motors
  4. It limits the total load to prevent voltage rise

Explanation

An RCCB monitors the difference between phase and neutral current and trips when leakage to earth exceeds its sensitivity, typically 30 mA for personnel protection. This limits the duration of shock and reduces fatal risk. It does not limit load current, correct power factor or rectify current.

Question 12Electrical Safety, First Aid and Workplace Practices

A small fire starts in a waste paper bin in the electrical workshop. Which action sequence is correct?

  1. Open all windows and fan the flames
  2. Raise the alarm, isolate nearby equipment and use the correct extinguisher Correct answer.
  3. Throw water on it and continue working
  4. Ignore it because it is small

Explanation

The correct sequence is to alert others, cut off power to nearby equipment and attack the fire with the extinguisher suited to the material burning. Early alarm and isolation prevent the fire from reaching live equipment. Fanning or ignoring a fire allows rapid spread.

Question 13Electrical Safety, First Aid and Workplace Practices

Which statement correctly describes the safe method of lifting a heavy distribution board with two workers?

  1. Bend at the waist and lift quickly with a jerk
  2. Twist the trunk while lifting to place the board on the wall
  3. Hold the load away from the body at arm's length
  4. Bend the knees, keep the back straight and lift together on a signal Correct answer.

Explanation

Safe manual handling keeps the load close to the body, uses leg muscles with knees bent and a straight back, and coordinates two-person lifts with a clear signal. Jerking, twisting and holding the load at arm's length load the spine and cause injury.

Question 14Electrical Safety, First Aid and Workplace Practices

Which of these is the accepted method for checking that a portable electric drill is safe before use?

  1. Ask the previous user whether it gave a shock
  2. Smell the motor and start work
  3. Inspect the cord, plug and earth, and test the insulation resistance Correct answer.
  4. Check only that the chuck rotates freely

Explanation

Before use, a portable tool should be inspected for damaged insulation, a sound plug and continuity of the earth, and its insulation resistance should be tested periodically. Functional checks alone do not reveal an insulation failure that could make the metal body live. Relying on another user's word is not a test.

Question 15Electrical Safety, First Aid and Workplace Practices

A worker's clothing catches fire after an arc flash. What should the worker do?

  1. Stop, drop to the ground and roll to smother the flames Correct answer.
  2. Run to the nearest water tap
  3. Wave the arms to cool the fabric
  4. Stand still and wait for the flames to die out

Explanation

Stop, drop and roll smothers the flames by cutting off oxygen and limits burns to the face and airway. Running fans the flames and spreads them over the body. Water taps and arm-waving do not extinguish burning clothing.

Question 16Electrical Safety, First Aid and Workplace Practices

What is the main hazard of using a metal ladder near an overhead line?

  1. The ladder may scratch the insulation without any risk
  2. The ladder overheats the overhead conductor
  3. The ladder becomes magnetic and attracts current
  4. The ladder can provide a conducting path to earth through the user Correct answer.

Explanation

A metal ladder is conductive, so contact with an overhead line can send current through the ladder and the person holding it to earth. Non-conducting ladders and safe approach distances are required near overhead lines. Scratching insulation or magnetic effects do not describe the real danger.

Question 17Electrical Safety, First Aid and Workplace Practices

In a three-point plug, why is the earth pin longer and thicker than the other two pins?

  1. So the plug can be inserted in any orientation
  2. So it makes the earth connection first and carries fault current safely Correct answer.
  3. So it can be gripped easily by the fingers
  4. So it can be used as a phase pin in an emergency

Explanation

The longer earth pin enters the socket first and leaves last, ensuring the metal body is earthed before live contact is made. Its greater thickness lets it carry fault current without overheating. It is not interchangeable with phase or neutral pins.

Question 18Electrical Safety, First Aid and Workplace Practices

A maintenance team must replace a fuse in a distribution board. Which choice reflects correct safety practice?

  1. Change the fuse while the board is live to save time
  2. Use any available fuse of higher rating
  3. Replace the fuse with a thicker wire to avoid future blowing
  4. Isolate and lock the incoming supply, then replace with the correct rated fuse Correct answer.

Explanation

The incoming supply must be isolated and locked before the fuse is touched, and the replacement must have the same rating and type as specified. Oversized fuses or wire links remove the protection and allow cables to overheat. Live fuse replacement exposes the worker to arc and shock.

Question 19Electrical Safety, First Aid and Workplace Practices

Which first aid step is appropriate for a casualty who is breathing but unconscious after an electric shock?

  1. Make the casualty stand and walk
  2. Give the casualty water to drink
  3. Place in the recovery position and monitor breathing until help arrives Correct answer.
  4. Leave the casualty alone to fetch tools

Explanation

An unconscious but breathing casualty should be placed in the recovery position to keep the airway clear and be monitored continuously until medical help arrives. Giving fluids to an unconscious person risks choking. Leaving the casualty alone risks airway obstruction being unnoticed.

Question 20Electrical Safety, First Aid and Workplace Practices

A workshop has a 30 mA RCCB on a socket circuit, yet a worker still receives a severe shock. Which explanation is most consistent with this situation?

  1. The RCCB was designed only for short circuits
  2. The RCCB sensitivity was too low to matter
  3. The socket circuit had no earthing at all
  4. The worker touched phase and neutral conductors, so no earth leakage was detected Correct answer.

Explanation

An RCCB responds only to current leaking to earth; a person touching phase and neutral together creates a current path that returns through the neutral, so the device sees no imbalance. This is why RCCBs do not replace isolation, insulated tools and safe working distance. Lack of earthing would actually increase leakage and trip the device.

Question 21Electrical Safety, First Aid and Workplace Practices

Two electricians disagree about the cause of nuisance tripping of an MCB on a motor circuit. Which investigation best follows a systematic fault-finding approach?

  1. Replace the MCB with a higher rating immediately
  2. Measure running current, check motor insulation and compare with the MCB rating Correct answer.
  3. Reset the MCB repeatedly and ignore the trips
  4. Increase the cable size without any measurement

Explanation

Systematic fault finding starts with measurement: running current against the rated current, insulation resistance of the motor and verification of the protective device rating. This identifies whether the trip is due to overload, insulation failure or a wrongly selected device. Upsizing the breaker or ignoring trips removes protection and risks fire.

Question 22Electrical Safety, First Aid and Workplace Practices

During a risk assessment for replacing a ceiling fan, which pair of controls best follows the hierarchy of risk control?

  1. Rely on gloves alone and work from a plastic chair
  2. Ask the client to switch off the light switch during work
  3. Work fast to reduce exposure time and skip the isolation
  4. Eliminate the hazard by isolating the circuit, then use a platform with guard rails Correct answer.

Explanation

The hierarchy of control prefers eliminating the hazard first, here by isolating and locking the circuit, followed by engineering controls such as a stable platform with guard rails. Personal protective equipment is the last line of defence and cannot be the only control. Improvised seating and light switches are not acceptable controls.

Question 23Electrical Safety, First Aid and Workplace Practices

A worker finds an unconscious colleague in a metallic tank used for cable pulling. Which action is correct before entering?

  1. Treat the space as confined, isolate energy sources and test the atmosphere Correct answer.
  2. Lower a rope and ask the casualty to tie it
  3. Enter at once with a torch to pull the person out
  4. Send a second worker in without any breathing apparatus

Explanation

A metallic tank is a confined space where oxygen deficiency or toxic gas can overcome rescuers, so energy sources must be isolated, the atmosphere tested and rescue done with proper equipment and a standby person. Rushing in without testing creates additional victims. An unconscious person cannot tie a rope.

Question 24Electrical Safety, First Aid and Workplace Practices

An electrician notices that the earth wire in a socket outlet has been disconnected and the socket is in daily use. What is the most appropriate immediate action?

  1. Connect the earth wire to the neutral terminal instead
  2. Note it in a register and check again next month
  3. Take the socket out of service, tag it and restore the earth before reuse Correct answer.
  4. Use the socket only for low-power appliances

Explanation

A socket without a protective earth can make appliance metalwork live under fault conditions, so it must be taken out of service, tagged and repaired before further use. Deferring the repair leaves a lethal hazard in daily use. Connecting earth to neutral is illegal and dangerous because the metalwork becomes live if the neutral opens.

Question 25Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

In an electrical circuit, what does the term 'potential difference' between two points measure?

  1. The opposition offered to current flow by the conductor
  2. The total charge flowing past a point each second
  3. The heat energy dissipated by the resistor per minute
  4. The work done per unit charge in moving charge between the two points Correct answer.

Explanation

Potential difference, measured in volts, is the work done per unit charge when charge moves between two points. It is the electrical 'pressure' that drives current through a circuit. Current in amperes measures charge flow per second, which is a different quantity.

Question 26Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

An ammeter is connected in a circuit to measure current. What does a reading of 2 A indicate about the circuit?

  1. The circuit resistance is 2 ohms at every point
  2. The supply delivers 2 watts to the load
  3. 2 coulombs of charge pass a cross-section every second Correct answer.
  4. 2 joules of energy are used by each coulomb of charge

Explanation

One ampere is defined as one coulomb of charge passing a point per second, so 2 A means 2 coulombs per second. Joules per coulomb define the volt, not the ampere. Power in watts depends on both current and voltage, so current alone cannot give watts.

Question 27Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A wire of uniform material is replaced by another wire of the same material and length but twice the cross-sectional area. How does its resistance change?

  1. It becomes half of the original value Correct answer.
  2. It becomes twice the original value
  3. It remains exactly the same
  4. It becomes four times the original value

Explanation

Resistance is inversely proportional to cross-sectional area for a given material and length, R = ρL/A. Doubling the area therefore halves the resistance. This is why thicker cables carry current with less voltage drop and less heating.

Question 28Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

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

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

Explanation

A voltmeter is connected in parallel so that it experiences the same potential difference as the component under test. It is designed with very high internal resistance so that it draws almost no current. An ammeter, by contrast, goes in series with the load.

Question 29Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 12 V battery is connected across a 6 Ω resistor. What current flows through the resistor?

  1. 0.5 A
  2. 18 A
  3. 72 A
  4. 2 A Correct answer.

Explanation

Ohm's law gives I = V/R, so 12 V divided by 6 Ω equals 2 A. The current rises when voltage rises and falls when resistance rises. Always keep units consistent, volts and ohms giving amperes.

Question 30Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A heater draws 5 A from a 230 V supply. What is the power consumed by the heater?

  1. 1150 W Correct answer.
  2. 46 W
  3. 0.02 W
  4. 235 W

Explanation

Electrical power in a resistive load is P = V × I, so 230 V × 5 A gives 1150 W. This is the rate at which electrical energy converts to heat. Dividing the same values would give no meaningful power quantity.

Question 31Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

What is the standard unit of electrical resistance, and what does one unit represent?

  1. The ohm, equal to one volt per ampere Correct answer.
  2. The farad, equal to one coulomb per volt
  3. The coulomb, equal to one ampere-second
  4. The watt, equal to one joule per second

Explanation

Resistance is measured in ohms, and one ohm is the resistance that allows one ampere to flow when one volt is applied. This follows directly from R = V/I. The watt, coulomb and farad measure power, charge and capacitance respectively.

Question 32Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

Which statement correctly describes the direction of conventional current in a metal conductor?

  1. Alternating randomly with no net direction of flow
  2. From the negative terminal through the external circuit to the positive terminal
  3. In the same direction as the drift of free electrons
  4. From the positive terminal through the external circuit to the negative terminal Correct answer.

Explanation

Conventional current is defined as flowing from the positive terminal, through the external circuit, to the negative terminal. Free electrons actually drift in the opposite direction, from negative to positive. The convention was fixed before the electron was discovered.

Question 33Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 230 V supply is applied to a 46 Ω heating element. What current does the element draw?

  1. 10580 A
  2. 276 A
  3. 5 A Correct answer.
  4. 0.2 A

Explanation

Using Ohm's law, I = V/R = 230/46 = 5 A. The element is treated as a pure resistance for this calculation. Checking with P = VI gives 1150 W, a realistic value for a small heater.

Question 34Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

Two resistors of 4 Ω and 6 Ω are connected in series across a 20 V supply. What is the current in the circuit?

  1. 0.5 A
  2. 20 A
  3. 2 A Correct answer.
  4. 10 A

Explanation

In series, resistances add, giving 4 + 6 = 10 Ω. Ohm's law then gives I = 20/10 = 2 A, and this same current flows through both resistors. The voltage divides across them in proportion to their resistance.

Question 35Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the equivalent resistance of the combination?

  1. 18 Ω
  2. 9 Ω
  3. 4.5 Ω
  4. 2 Ω Correct answer.

Explanation

For two resistors in parallel, R = (R1 × R2)/(R1 + R2) = (6 × 3)/(6 + 3) = 18/9 = 2 Ω. The equivalent resistance is always smaller than the smallest branch resistance. This is why adding parallel paths lowers total resistance.

Question 36Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 60 W lamp operates on a 230 V supply. What current does it take, approximately?

  1. 0.004 A
  2. 0.26 A Correct answer.
  3. 13800 A
  4. 3.83 A

Explanation

Rearranging P = VI gives I = P/V = 60/230 ≈ 0.26 A. This small current is typical of a domestic lamp. The value also lets you find resistance from R = V/I, about 880 Ω.

Question 37Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A resistor of 100 Ω carries a current of 0.5 A. What power is dissipated in it?

  1. 50 W
  2. 200 W
  3. 25 W Correct answer.
  4. 0.005 W

Explanation

Using P = I²R gives (0.5)² × 100 = 0.25 × 100 = 25 W. Alternatively, the voltage is 50 V and P = VI also gives 25 W. Both routes confirm the same answer.

Question 38Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

What happens to the resistance of a metallic conductor when its temperature is increased?

  1. It falls to zero once the conductor becomes warm
  2. It increases because lattice vibrations scatter the charge carriers more Correct answer.
  3. It decreases because more free electrons are released
  4. It stays constant because resistance depends only on length and area

Explanation

In metals, higher temperature increases lattice vibration, which scatters drifting electrons more often, so resistance rises. This is why a cold filament has much lower resistance than a hot one. The effect is described by the temperature coefficient of resistance.

Question 39Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 12 V supply drives 3 A through a resistor. What is the resistance, and how much power is dissipated?

  1. 0.25 Ω and 4 W
  2. 4 Ω and 0.25 W
  3. 36 Ω and 4 W
  4. 4 Ω and 36 W Correct answer.

Explanation

Ohm's law gives R = V/I = 12/3 = 4 Ω. Power is P = VI = 12 × 3 = 36 W, which also matches I²R = 9 × 4 = 36 W. Both quantities come from the same two measured values.

Question 40Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

In a series circuit, which quantity is the same through every component?

  1. Current Correct answer.
  2. Voltage
  3. Resistance
  4. Power

Explanation

A series circuit provides only one path, so the same current passes through every component. The supply voltage divides among the components in proportion to their resistances. Resistance and power differ from component to component.

Question 41Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

In a parallel circuit, which quantity is the same across every branch?

  1. Voltage Correct answer.
  2. Resistance
  3. Charge stored
  4. Current

Explanation

Each parallel branch is connected directly across the same two nodes, so every branch has the same voltage. The total current splits among the branches according to their resistances. This is why domestic appliances are wired in parallel.

Question 42Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 1.5 V cell delivers a current of 0.3 A for 60 seconds. How much charge passes through the circuit?

  1. 0.005 C
  2. 1800 C
  3. 18 C Correct answer.
  4. 2.7 C

Explanation

Charge equals current multiplied by time, Q = I × t = 0.3 × 60 = 18 C. The voltage value is not needed for this calculation. The same relation underlies the definition of the ampere as a coulomb per second.

Question 43Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 100 W lamp is used for 5 hours. How much electrical energy does it consume?

  1. 500 kWh
  2. 0.02 kWh
  3. 20 kWh
  4. 0.5 kWh Correct answer.

Explanation

Energy in kilowatt-hours equals power in kilowatts multiplied by time in hours: 0.1 kW × 5 h = 0.5 kWh. This is the unit used for domestic electricity billing. The result equals 1.8 million joules when converted.

Question 44Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 230 V supply feeds two parallel resistors of 115 Ω each. What total current does the supply deliver?

  1. 4 A Correct answer.
  2. 2 A
  3. 0.5 A
  4. 1 A

Explanation

The parallel equivalent is 115/2 = 57.5 Ω, so I = 230/57.5 = 4 A. Equivalently, each branch draws 2 A and the branch currents add. Parallel paths always share the total current.

Question 45Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A potential divider uses R1 = 2 kΩ and R2 = 3 kΩ in series across 10 V. What is the voltage across R2?

  1. 6 V Correct answer.
  2. 4 V
  3. 3 V
  4. 10 V

Explanation

The output across R2 follows V2 = V × R2/(R1 + R2) = 10 × 3/5 = 6 V. The larger resistance drops the larger share of the supply voltage. The remaining 4 V appears across R1.

Question 46Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A real cell has an emf of 12 V and an internal resistance of 1 Ω. It supplies a load of 5 Ω. What is the terminal voltage?

  1. 12 V
  2. 2 V
  3. 10 V Correct answer.
  4. 5 V

Explanation

Total resistance is 5 + 1 = 6 Ω, so current is 12/6 = 2 A. The internal drop is 2 A × 1 Ω = 2 V, so terminal voltage is 12 − 2 = 10 V. Terminal voltage is always below emf when the cell delivers current.

Question 47Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

Three equal resistors are connected in parallel, and the combination has a resistance of 2 Ω. What is the resistance of each resistor?

  1. 6 Ω Correct answer.
  2. 0.67 Ω
  3. 18 Ω
  4. 2 Ω

Explanation

For n equal resistors in parallel, R_total = R/n, so R = n × R_total = 3 × 2 = 6 Ω. Checking: 1/6 + 1/6 + 1/6 = 1/2, giving 2 Ω. Parallel combinations are always smaller than any single branch.

Question 48Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 230 V heater of 46 Ω is run for 2 hours. What energy does it consume, in kWh?

  1. 0.23 kWh
  2. 230 kWh
  3. 1.15 kWh
  4. 2.3 kWh Correct answer.

Explanation

Power is P = V²/R = 230²/46 = 1150 W, or 1.15 kW. Energy is 1.15 kW × 2 h = 2.3 kWh. Always convert watts to kilowatts before multiplying by hours.

Question 49Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

A 100 Ω resistor and a 200 Ω resistor are connected in parallel across 100 V. How does the total power compare with the power in the 100 Ω resistor alone?

  1. Total power is 150 W, which is 1.5 times the power in the 100 Ω resistor Correct answer.
  2. Total power is 300 W, three times the power in the 100 Ω resistor
  3. Total power is 100 W, equal to the power in the 100 Ω resistor
  4. Total power is 50 W, less than the power in the 100 Ω resistor

Explanation

The 100 Ω branch draws 1 A and dissipates 100 W, while the 200 Ω branch draws 0.5 A and dissipates 50 W. The total is 150 W, so it is 1.5 times the power in the 100 Ω resistor. In parallel, both branches see the full supply voltage.

Question 50Basic Electrical Fundamentals (voltage, current, resistance, power, Ohm's law)

An electrician measures the potential difference across a resistor in a live circuit. Which statement correctly describes what this potential difference represents?

  1. The opposition offered by the resistor to the flow of charge
  2. The energy converted per unit charge between the two points of the resistor Correct answer.
  3. The rate at which the resistor converts electrical energy into heat
  4. The total charge that flows through the resistor each second

Explanation

Potential difference is defined as the work done (energy converted) per unit charge when charge moves between two points, so it is measured in joules per coulomb, which is the volt. It is not a rate of charge flow, a rate of energy conversion, or an opposition to current; those describe current, power and resistance respectively.