# Top 100 Basic Electrical Engineering MCQ

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:

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

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 ________:

1. Potential
2. Charge
3. Capacity
4. Temperature

## 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:

1. It will remain the same
2. It will increase by 9 times
3. It will decrease by 9 times
4. It will increase by three times

Answer: 2. It will increase by 9 times

Illustration: Power (P) = I2R

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

P(N) = (3I)2R = 9 I2R = p (I2R) = 9 (P)

Power increases by three times

## Role of EMF in Electric Circuits

Role of EMF in electric circuits is to:

1. Increase resistance of circuit
2. Decrease resistance of circuit
3. Provide potential difference
4. All of these

Correct answer: 3. Provide potential difference

## Semiconductors have which type of temperature coefficient of resistance

Semiconductors have ____________ temperature coefficient of resistance:

1. Negative
2. Positive
3. Zero
4. None of these

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:

1. Current
2. Inductivity
3. Resistivity
4. Resistance

## 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:

1. 0.9 Ω
2. 3.33 Ω
3. 1.5 Ω
4. 2.5 Ω
5. 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:

1. Increase
2. Decrease
3. Remains the same as it was before

## What happens when cells are arranged in parallel

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

1. The EMF increases
2. The EMF decreases
3. The current capacity increases
4. 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:

1. R1 = R2
2. R1 = 2R2
3. R1 = 1 + R2
4. 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. 1.15 ohms
2. 11.5 ohms
3. 20 ohms
4. 608 kohms

Explanation: R = V2/P

R = (230)2/2645 = 20 ohms

## Electric current is scalar or vector

Electric current is:

1. Scalar quantity
2. Vector 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:

1. Aluminum
2. Tungsten
3. Silver
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:

1. Length of material
2. Nature of material and temperature
3. Cross sectional area of material
4. 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:

1. E.M.F
2. Magnetostatic force per meter2
3. Charge
4. Capacitance

Ampere – second or coulomb is unit of Electric charge

## Current division principle is applicable for

Current division principle is applicable for:

1. Series circuits only
2. Parallel circuits only
3. Both of these
4. None of these

Correct answer: 2. Parallel circuits only

## Correct statement of VDR Principle

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

1. Vx = {(Rx + Req)/ Req} * Vs
2. Vx = (Rx / Req) * Vx
3. Vx = (Req / Rx) * Vs
4. Vx = (Rx / Req) * Vs

Correct answer: 4. Vx = (Rx / Req) * Vs

## Basic Resistance formula

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

1. R = ρlA
2. R = ρl + A
3. R = ρl/A
4. 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:

1. More power losses occur in series
2. Series circuit is complex to design
3. Devices have different current rating
4. 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:

1. 50 seconds
2. 100 seconds
3. 1250 seconds
4. 562500 seconds
5. None of these

## The resistance of a linear circuit

The resistance of a linear circuit:

1. Changes with a change in voltage
2. Changes with a change in current
3. Doesn’t changes with change in voltage and current
4. 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?

1. 2 V
2. 3 V
3. 6 V
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:

1. 0.25 Ω
2. 0.5 Ω
3. 1 Ω
4. 2 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:

1. Positive
2. Negative
3. Zero
4. None of these

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:

1. Its dimension
2. Its length
3. Its material
4. Its cross sectional area
5. All of these

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:

1. It divides in the direct ratio of resistance
2. It divides in the inverse ratio of resistance
3. 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:

1. All passive elements
2. All active elements
3. A single voltage or current source
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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