Question

a bulb is rated 5 volts ;500mA . calculated rated power and the resistance of bulb when it glows

Answer 1

P.D = 5 V

I = 500mA = 5 x 10-1 A

a) Power = VI

  = 5 x 5 x 10-1

  = 2.5 Watt

b) Resistance = V / I

  = 5 / 5 x 10-1

  = 10 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.

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