Top 100 Basic Electrical Engineering MCQ for competitive exams, quizzes, and tests.

## Electric current is measured by which instrument

Electric current is measured by which instrument:

- Voltmeter
- Ammeter
- Ohmmeter
- Wattmeter

Correct answer: 2. Ammeter

The SI unit of electric current is ampere’s which is measured by using ammeter

## No current flows through two bodies if they have same

No current flows through two bodies if they have same ________:

- Potential
- Charge
- Capacity
- Temperature

Correct answer: 1. Potential

## Effect of tripling current on the power of constant resistance circuit

In the certain circuit, having constant resistance the current is tripled, what will happen to power:

- It will remain the same
- It will increase by 9 times
- It will decrease by 9 times
- It will increase by three times

Answer: 2. It will increase by 9 times

Illustration: Power (P) = I^{2}R

By increasing current by three times I = 3I new power P(N) becomes

P(N) = (3I)^{2}R = 9 I^{2}R = p (I^{2}R) = 9 (P)

Power increases by three times

## Role of EMF in Electric Circuits

Role of EMF in electric circuits is to:

- Increase resistance of circuit
- Decrease resistance of circuit
- Provide potential difference
- All of these

Correct answer: 3. Provide potential difference

## Semiconductors have which type of temperature coefficient of resistance

Semiconductors have ____________ temperature coefficient of resistance:

- Negative
- Positive
- Zero
- None of these

Correct answer: 1. Negative

In semiconductors, an increase in the temperature of material results in an increase in charge-carrier concentration. This, in turn, results in availability of a higher number of charge carriers thus increasing the conductivity of the semiconductors. which decreases the resistivity of the semiconductor material with the rise in temperature.

## What is the reciprocal of conductivity

What is the reciprocal of conductivity:

- Current
- Inductivity
- Resistivity
- Resistance

Correct answer: 3. Resisivity

## Resistance at any diameter of wire forming circle

Certain wire has a resistance of 10 Ω. It is bent to form a circle. What resistance will an ohmmeter connected on any diameter of the circle will measure ideally:

- 0.9 Ω
- 3.33 Ω
- 1.5 Ω
- 2.5 Ω
- 5 Ω

Correct answer 4. 2.5 Ω

Illustration:

5 ohm || 5 ohm = 2.5 ohms (** MCQs on Series and Parallel resistors**)

## Effect of adding new series resistors on Power dissipation of previous resistor

A resistor having resistance ‘R’ dissipates power ‘P’ when connected to a voltage source E. If another resistor ‘R1’ is connected in series to ‘R’, then the power ‘P’ dissipated by ‘R’ will:

- Increase
- Decrease
- Remains the same as it was before

Correct answer: 1. Decrease

## What happens when cells are arranged in parallel

Which of the following statement is correct about parallel connection of cells:

- The EMF increases
- The EMF decreases
- The current capacity increases
- The current capacity decreases

Correct answer: 3. The current capacity increases

Similar MCQ: Electric current is measured in

## Two lamps having rated powers of 100 W@230 V and 50 W @230 V respectively. If R1 = 100 W lamp and R2 = 50 W lamp, then the ratio of their resistances is

Two lamps having rated powers of 100 W@230 V and 50 W @230 V respectively. If R1 is the resistance of 100 W lamp and R2 is resistance of 50 W lamp, then the ratio of their resistances is:

- R1 = R2
- R1 = 2R2
- R1 = 1 + R2
- R1 = R2/2

Correct answer: 4. R1 = R2/2

Explanation: Since both resistors are rated for same voltage, then

R1 * P1 = R2 * P2

R1 * 100 = R2 * 50

R1 = R2 * 50 / 100

*R1 = R2/2*

## The nameplate of a water heater mentions 2645 W, 230 V. The resistance of element is

The nameplate of a water heater mentions 2645 W, 230 V. The resistance of element is:

- 1.15 ohms
- 11.5 ohms
- 20 ohms
- 608 kohms

Correct answer: 3. 20 ohms

Explanation: R = V^{2}/P

R = (230)^{2}/2645 = 20 ohms

## Electric current is scalar or vector

Electric current is:

- Scalar quantity
- Vector quantity

Correct answer: 1. Scalar quantity

Electric current is defined as the amount of charge passing through a surface per unit time.

*I = Q/t*

Since both components in formula (charge and the time) are scalar quantities the current is a scalar quantity.

Good to know: *While current is a scalar quantity, the current density is not. Current density is actually a vectorial quantity*

## Which one of the following is an an example of non-ohmic resistance

Which one of the following is an an example of non-ohmic resistance:

- Aluminum
- Tungsten
- Silver
- Carbon

Correct answer: 4. Carbon

*Carbon resistance is an example of non-ohmic resistance.*

## The temperature coefficient of resistance depends on on which factor

The temperature coefficient of resistance depends on on which factor:

- Length of material
- Nature of material and temperature
- Cross sectional area of material
- Volume of material

Correct answer: 2. Nature of material and temperature

## Ampere – second is a unit of which electrical quantity

Ampere – second is a unit of which electrical quantity:

- E.M.F
- Magnetostatic force per meter
^{2} - Charge
- Capacitance

Correct answer: 3. Charge

Ampere – second or coulomb is unit of Electric charge

## Current division principle is applicable for

Current division principle is applicable for:

- Series circuits only
- Parallel circuits only
- Both of these
- None of these

Correct answer: 2. Parallel circuits only

See also: Top 10 MCQ on Current Divider Rule

## Correct statement of VDR Principle

Which of the equations given below correctly express the voltage divider principle:

- V
_{x}= {(R_{x}+ R_{eq})/ R_{eq}} * V_{s} - V
_{x}= (R_{x}/ R_{eq}) * V_{x} - V
_{x}= (R_{eq}/ R_{x}) * V_{s} - V
_{x}= (R_{x}/ R_{eq}) * V_{s}

Correct answer: 4. V_{x} = (R_{x} / R_{eq}) * V_{s}

## Basic Resistance formula

The resistance R of a material having length l and area of cross section A is mathematically expressed as:

- R = ρlA
- R = ρl + A
- R = ρl/A
- R = ρl (1+ σς/A)

Correct answer: 3. R = ρl/A

## Electrical devices and appliances are not connected in series because

Electrical devices and appliances are not connected in series because:

- More power losses occur in series
- Series circuit is complex to design
- Devices have different current rating
- All of these

Correct answer: 3. Devices have different current rating

## How long does it take for a 75-watt soldering iron to dissipate the energy of 7500 J

How long does it take for a 75-watt soldering iron to dissipate the energy of 7500 J:

- 50 seconds
- 100 seconds
- 1250 seconds
- 562500 seconds
- None of these

Correct answer: 2. 100 seconds

## The resistance of a linear circuit

The resistance of a linear circuit:

- Changes with a change in voltage
- Changes with a change in current
- Doesn’t changes with change in voltage and current
- 1 and 2

Correct answer: 3. Doesn’t changes with change in voltage and current

## To find the value of voltage sources connected to 6 ohms resistor

A 6-ohm resistor connects in series to an unknown voltage source. An ammeter when connected in series measures a current flow of 2 Amps. What is the value of the voltage source?

- 2 V
- 3 V
- 6 V
- 12 V

Correct answer: 4. 12 V

From Ohm’s law formula: V = IR = 2 A * 6 ohms = 12 V

## Four cells of 2 Ω are connected in parallel. The overall resistance of the battery is:

Four cells of 2 Ω are connected in parallel. The overall resistance of the battery is:

- 0.25 Ω
- 0.5 Ω
- 1 Ω
- 2 Ω

Correct answer: 2. 0.5 Ω

*For same resistors in parallel: R/n = 2 ohm/4 = 0.5 Ω*

## What is the Temperature coefficient of insulators

Generally, the temperature coefficient of insulators is:

- Positive
- Negative
- Zero
- None of these

Correct answer: 2. Negative

**When the resistance of materials falls with an increase in temperature, the material is said to posses a negtaive temperature coefficient. Generally insulators have a negative temperature coefficient.**

## The specific resistance of a wire depends on

The specific resistance of a wire depends on:

- Its dimension
- Its length
- Its material
- Its cross sectional area
- All of these

Correct answer: 3. Its material

*The specific resistance of a conductor is the resistance of a conductor that has unit length and a unit area of cross-section. Note that specific resistance is a property of the material and it depends on the material.*

## When resistors are connected in parallel which of following is correct about current

When resistors are connected in parallel which of following is correct about current:

- It divides in the direct ratio of resistance
- It divides in the inverse ratio of resistance
- None of the above

Correct answer: 2. It divides in the inverse ratio of resistance

## The superposition theorem is applied when the circuit contains

The superposition theorem is applied when the circuit contains:

- All passive elements
- All active elements
- A single voltage or current source
- Multiple sources

Correct answer: 4. Multiple sources

The superposition theorem is applied when circuit contains two or more than two sources.

Statement of Superposition theorem:

*The total current through or voltage across a resistor or branch can be determined by summing the effects due to each independent source.*

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Voltage and ampere nikaalne ka sutra

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