Basic Electrical Engineering MCQs Part 7

Basic Electrical Engineering MCQs Part 7

A substance having number of valence electrons less than 4 is usually

A substance having number of valence electrons less than 4 is usually

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

Correct answer: 3. A conductor

Conductivity is reciprocal of

Conductivity is reciprocal of:

1. Resistance
2. Current density
3. Resistivity
4. None of these

Correct answer: 3. Resistivity

The specific resistance of certain wire that is 1.5 m long, has 0.5 mm diamter, and having a resistance 5 will be

The specific resistance of certain wire that is 1.5 m long, has 0.5 mm diamter, and having a resistance 5 will be:

1. 65 * 10^-8 Ω-m
2. 23 * 10^-8 Ω-m
3. 37 * 10^-8 Ω-m
4. 44 * 10^-8 Ω-m

Correct answer: 1. 65 * 10^-8 Ω-m

Solution:

Area = πr² = π(d/2)² = 1.963E-07

R = ρl/A OR ρ = RA/l

ρ = 5 * 1.963E-07 / 1.5  = 6.54 * 10^-07 Ω-m = 65 * 10^-8 Ω-m

The electric power dissipated in a resistor in terms of its conductance G and voltage V across it is mathematically expressed in the form

The electric power dissipated in a resistor in terms of its conductance G and voltage V across it is mathematically expressed in the form:

1. V²G
2. V²/G
3. GV²
4. G/V²

Correct answer: 1. V²G

Explanation:

Power dissipated (P) = V²/R = V²G

The SI unit of conductivity is

The SI unit of conductivity is:

1. mho/m
2. mho-m
3. ohm-m
4. ohm/m

Correct answer: 1. mho/m