Drift Velocity & Electrical Resistance MCQs
Drift Velocity & Electrical Resistance – MCQs
Class: 12 | Subject: Physics |
Section: Current Electricity |
Topic: Drift Velocity & Electrical Resistance
Based on: NCERT Syllabus | CBSE Board Examination Standard
Based on: NCERT Syllabus | CBSE Board Examination Standard
Instructions: These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 12 Board Examination preparation.
1. Drift velocity is the average velocity of:
Answer: B
It is the average velocity acquired by free electrons under an applied electric field.
It is the average velocity acquired by free electrons under an applied electric field.
2. Drift velocity is proportional to:
Answer: B
vd = μE → directly proportional to electric field.
vd = μE → directly proportional to electric field.
3. Unit of drift velocity:
Answer: A
Velocity unit is metre per second.
Velocity unit is metre per second.
4. Mobility is defined as:
Answer: A
Mobility = drift velocity per unit electric field.
Mobility = drift velocity per unit electric field.
5. Mobility unit:
Answer: A
Derived from vd/E.
Derived from vd/E.
6. Current density J =
Answer: A
Standard relation.
Standard relation.
7. Resistivity unit:
Answer: A
SI unit Ω metre.
SI unit Ω metre.
8. Resistance depends on:
Answer: D
R = ρL/A.
R = ρL/A.
9. Temperature ↑ → resistance of metals:
Answer: B
Lattice vibrations increase collisions.
Lattice vibrations increase collisions.
10. Drift velocity small because:
Answer: A
Frequent collisions reduce speed.
Frequent collisions reduce speed.
11. Relaxation time is:
Answer: A
Average time between collisions.
Average time between collisions.
12. vd proportional to relaxation time:
Answer: A
vd = eEτ/m.
vd = eEτ/m.
13. Conductivity is reciprocal of:
Answer: B
σ = 1/ρ.
σ = 1/ρ.
14. Good conductor has:
Answer: B
Low resistivity.
Low resistivity.
15. Microscopic Ohm’s law:
Answer: A
Relates field & current density.
Relates field & current density.
16. Number density unit:
Answer: A
Charge carriers per volume.
Charge carriers per volume.
17. Current density direction:
Answer: B
Conventional current opposite electrons.
Conventional current opposite electrons.
18. Resistance zero at:
Answer: B
Below critical temperature.
Below critical temperature.
19. Silver has:
Answer: B
Best conductor.
Best conductor.
20. Drift velocity depends on:
Answer: D
vd = eEτ/m includes all factors.
vd = eEτ/m includes all factors.
