Question

A bulb is rated at 5.0 volt, 100 ma. calculated its (i) power (ii) resistance.

Answer 1

voltage = v = 5 v
current = I = 100ma = 100/1000 = 0.1 a
power= ?
resistance = ?

1)
P = VI
P = 5×0.1
P = 0.5 W
power 0.5 Watt

2)
R = V/I
R = 5/0.1
R = 50 ohm
resistance 50 ohm

Answer 2

1000mA = 1A

So, 100mA = 100/1000 = 0.1A

Potential difference = 5V (given)  

Resistance = V/I = 5/0.1 = 50 Ohm

Power = I x I x R = 0.1 x 0.1 x 50 = 0.5 Watt.

THANKS.

HOPE THIS HELPS YOU.