Basic Electrical Engineering MCQs Part 6

Contents

- 1 Certain length of wire has a resistance of 6 ohms. What is the value of resistance of wire that is three times long and having two times the cross-sectional area
- 2 A resistor having color coding Brown Black Red
- 3 A solid cube of silver has mass 50 g. Considering density of silver 10.5 g/cm³ and resistivity to be 0.0000016 Ωcm. The resistance between two opposite faces of cube will be
- 4 Temperature coefficient of resistance of Eureka is
- 5 The mass of a proton is how many times the mass of electron

## Certain length of wire has a resistance of 6 ohms. What is the value of resistance of wire that is three times long and having two times the cross-sectional area

Certain length of wire has a resistance of 6 ohms. What is the value of resistance of wire that is three times long and having two times the cross-sectional area:

- 1 ohm
- 4 ohm
- 9 ohm
- 12 ohm

Correct answer: 3. 9 ohm

Solution:

R1 = ρ * l1 /a1

R2 = ρ * l2 /a2

R2 / R1 = (l2 / a2) * (a1 / l1)

R2 / R1 = (3l/2a) * (a/l) = 3/2 = 1.5

R2/R1 = 1.5

R2 = 1.5 * 6 = 9 ohms

## A resistor having color coding Brown Black Red

A resistor having color coding:

Brown Black Red will have resistance:

- 1 kΩ ± 10%
- 1 kΩ ± 20%
- 2 kΩ ± 10%
- 2 kΩ ± 20%

Correct answer: 2. 1 kΩ ± 20%

Brown, Black = 10

Red = 10^2

None = ±20%

## A solid cube of silver has mass 50 g. Considering density of silver 10.5 g/cm³ and resistivity to be 0.0000016 Ωcm. The resistance between two opposite faces of cube will be

A solid cube of silver has mass 50 g. Considering density of silver 10.5 g/cm³ and resistivity to be 0.0000016 Ωcm. The resistance between two opposite faces of cube will be:

- 3.29 * 10^-7 Ω
- 5.42 * 10^-7 Ω
- 9.51 * 10^-7 Ω
- None of these

Correct answer: 3. 9.51 * 10^-7 Ω

Solution:

Volume of cube = Mass/Density = 50/10.5 = 4.76 cm³

Each side of cube =4.76190476190476^1/3 = 1.68 cm

R = ρl/A = 9.51*10^-7 Ω

## Temperature coefficient of resistance of Eureka is

Temperature coefficient of resistance of Eureka is:

- Positive
- Negative
- Zero
- None of these

Correct answer: 1. Positive

## The mass of a proton is how many times the mass of electron

The mass of a proton is how many times the mass of electron.

- 1 time (is equal to)
- 3 times less than
- 400 times
- About 1837 times

Correct answer: 4. About 1837 times