# Basic Electrical Engineering MCQs Part 3

Basic Electrical Engineering MCQs Part 3

## A substance having number of valence electrons equal to 4 is usually

A substance having number of valence electrons equal to 4 is usually

1. An insulator
2. A semiconductor
3. A conductor
4. None of the above

## Constantan wire is used for making standard resistor since it has

Constantan wire is used for making standard resistor since it has:

1. High specific resistance
2. Low specific resistance
3. High melting point
4. Negligibly small temperature coefficient of resistance

Correct answer: 4. Negligibly small temperature coefficient of resistance

## The specific resistance of material of wire depends on

The specific resistance of material of wire depends on:

1. Mass
2. Length
3. Area of cross-section
4. None of these

Correct answer: 4. None of these

Explanation: Electrical resistivity also known as specific electrical resistance or volume resistivity is a fundamental property of a material that measures how strongly it resists electric current. The specific resistance of material of wire depends on the material from which it is fabricated and it doesnâ€™t depends on the mass, length or area of cross-section of material.

## Electric current in liquids is due to flow of

Electric current in liquids is due to flow of:

1. Electrons
2. Positive ions
3. Negative ions
4. 2 and 3

Correct answer: 4. 2 and 3

## An electron is moving in cirlce of radius 4.5*10^-11 m at a frequency of 5.28*10^15 revolutions per second. The equivalent current is approximately

An electron is moving in cirlce of radius 4.5*10^-11 m at a frequency of 5.28*10^15 revolutions per second. The equivalent current is approximately:

1. 4.2 * 10^-4 A
2. 2.3 * 10^-4 A
3. 5.86 * 10^-4 A
4. 8.45 * 10^-4 A

Correct answer: 4. 8.45 * 10^-4 A

Solution:

Current = Charge/Time period = Charge * Frequency

=1.6810^-19 * 5.28*10^15 = 8.45 * 10^-4 A

The drift velocity of free electrons is of the roder:

1. 1 m/s
2. 10^-3 m/s
3. 10^-5 m/s
4. 10^-9 m/s