In carbon resistor colour code, if the third band is of silver, it indicates
A.
that three zeros are to be added to indicate the resistance value
B.
multiplier is 0.01
C.
multiplier is 0.1
D.
tolerance is ± 5%
Answer: Option B
42.
In a metal, the drift velocity of electrons in the presence of a electric field E is
A.
proportional to E
B.
proportional to E
C.
inversely proportional to E
D.
proportional to E2
Answer: Option A
Explanation:
Drift velocity is proportional to field strength.
43.
At a temperature of about 1 K, aluminium is a
A.
conductor
B.
insulator
C.
photoconductor
D.
superconductor
Answer: Option D
44.
An electron is moving in a circular orbit of radius R at angular velocity ω0 in a field free space. If a magnetic field B is created, the velocity of electron ω will be given by the equation
A.
B.
C.
D.
Answer: Option A
45.
If v is the velocity of electron, tc is the average time between collisions, the mean free path λ = vtc.
A.
True
B.
False
Answer: Option A
46.
Assertion (A): An electron having charge – e and mass m and lying in an electric field E is subjected to an acceleration – (e/m) E.
Reason (R): If there are n electrons/m3 moving with velocity vx and each electron has a charge – e, the current density J = – nevx.
A.
Both A and R are true and R is correct explanation of A
B.
Both A and R are true but R is not correct explanation of A
C.
A is true but R is false
D.
A is false but R is true
Answer: Option B
47.
When a pentavalent impurity is added, the semiconductor becomes
A.
p type
B.
n type
C.
intrinsic
D.
neutral
Answer: Option B
48.
In body centred cubic structure, comers and centre of the cube are occupied by identical atoms.
A.
True
B.
False
Answer: Option A
49.
For a multiplate capacitor having n plates, A as area of each plate, the capacitance is proportional to
A.
n A
B.
(n – 1) A
C.
(n + 1) A
D.
Answer:Option B
Explanation:
If the number of plates is n, the number of capacitors is (n – 1).
50.
The orientation polarization is
directly proportional to temperature
inversely proportional to temperature
inversely proportional to square of permanent dipole moment
directly proportional to square of permanent dipole moment.
