Electric Current (Drift Velocity, Mobility and their Relation with Electric Current) NEET Questions

Physics - Current Electricity

Electric Current (Drift Velocity, Mobility and their Relation with Electric Current) MCQ Questions


1.
The drift velocity of free electrons in a conductor of length L when a potential difference V is applied across its ends is v_d. If the length of the conductor is doubled keeping the potential difference same, the new drift velocity will be:
A.
v_d
B.
2v_d
C.
v_d/2
D.
4v_d
😑 View Answer Rough Work Error
ANSWER :
C. v_d/2
2.
The relation between current density j, number density of electrons n, charge e, and drift velocity v_d is:
A.
j = nev_d
B.
j = ne/v_d
C.
j = nev_d²
D.
j = n²ev_d
😑 View Answer Rough Work Error
ANSWER :
A. j = nev_d
3.
Mobility μ of a charge carrier is defined as:
A.
Current per unit area
B.
Resistance per unit length
C.
Charge per unit time
D.
Drift velocity per unit electric field
😑 View Answer Rough Work Error
ANSWER :
D. Drift velocity per unit electric field
4.
The SI unit of mobility is:
A.
m·V/s
B.
m²/(V·s)
C.
V·s/m²
D.
m/(V·s²)
😑 View Answer Rough Work Error
ANSWER :
B. m²/(V·s)
5.
If a current of 1 A flows through a conductor, the number of electrons crossing any cross-section per second is approximately:
A.
1.6 × 10¹⁹
B.
6.25 × 10¹⁸
C.
9.1 × 10³¹
D.
6.02 × 10²³
😑 View Answer Rough Work Error
ANSWER :
B. 6.25 × 10¹⁸
6.
The drift velocity of electrons in a metallic conductor is of the order of:
A.
10⁻¹⁰ m/s
B.
10⁸ m/s
C.
10⁻⁴ m/s
D.
10⁵ m/s
😑 View Answer Rough Work Error
ANSWER :
C. 10⁻⁴ m/s