electric current and magnetism - Category wise Question and Answer Practice Test with Solutions

Question : 16

To use a transistor as an amplifier

a) no bias voltage is required

b) both junctions are forward biased

c) The emitter base junction is forward biased and the base collector junction is reverse biased

d) both junctions are reverse biased

Question : 17 [IAS (Pre) 2001]

Two wires have their lengths, diameters and resistivities all in the ratio of 1 : 2. If the resistance of the thinner wire is 10 ohm, the resistance of the thicker wire is

a) 20 ohm

b) 5 ohm

c) 10 ohm

d) 40 ohm

Question : 18 [NDA]

Assertion (A) :
A person stands at a distance of 1m in front of a concave mirror. If the radius of curvature of the mirror is 4m, the image of the person lies at a distance 2m behind the mirror.
Reason (R) :
The general mirror equation confirms the location of the image from the mirror and it could be a real image.

a) A is true but R is false

b) Both A and R are individually true and R is the correct explanation of A

c) Both A and R are individually true but R is NOT the correct explanation of A

d) A is false but R is true

Question : 19

A bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased, while keeping the voltage of the source constant, then bulb will

a) give less intense light

b) give light of same intensity before

c) give more intense light

d) stop radiating light

Question : 20 [PCS (Mains) 2002]

Consider the following statements.
Assertion (A):
Lightning conductors prevent buildings from damages in the event of lightning strike.
Reason (R):
The electric charge conduct to ground through the wire, instead of passing through the structure.
Select the correct answer using the codes given below.
Code

a) (A) is true, but (R) is false

b) Both (A) and (R) are true and (R) is the correct explanation of (A)

c) Both (A) and (R) are true, but (R) is not the correct explanation of (A)

d) (A) is false, but (R) is true