Question

20
The ratings of three bulbs P, Q, R are 120V/24W ,120V/60 W and 240V/60 W respectively. Identify
the ascending order of their resistance.

(A) P, Q, R. (B) Q, PR (C) R,P,Q (D) Q, R,P​

Answer 1

Answer:

Given,

First bulb P = 120V/24W

We know that Ampere = Watts/Volts

= 24/120

= 0.2Amp

To find resistance,

By applying R = V/I

= 120/0.2

= 600Ohm.

Second bulb Q = 120V/60W

Ampere = Watts/Volts

= 60/120

= 0.5Amp.

To find resistance,

By applying, R = V/I

= 120/0.5

= 240Ohm.

Third bulb R = 240V/60W

Ampere = Watts/Volts

= 60/240

= 0.25Amp.

To find resistance,

By applying, R = V/I

= 240/0.25

= 960Ohm.

So, the ascending order of resistance is Q,P,R.