Question

(a) Define electric power. State it's unit.
Also derive formula of power P=V x I
(b) Which will have higher resistance: a
50w lamp bulb or a 25w and by how
many times?

Answer 1

Ans.a    Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.

Ans.b Given two bulbs.

POWER OF FIRST BULB=P1=50W

POWER OF SECOND BULB=P2=25 W

If same voltage V is used for two bulbs.

Then,

P=V^2/R

We can see that POWER is inversely proportional to RESISTANCE.

A bulb with more power will have less RESISTANCE.

So, bulb with 25W will offer more RESISTANCE.

R1=V^2/P1

R2=V^2/P2

R1/R2= P2/P1

R1/R2=25/50=1/2

R12=2R1

THEREFORE , SECOND BULB WITH POWER 25W WILL OFFER MORE ( DOUBLE) RESISTANCE THAN FIRST BULB.

Answer 2

Answer:

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Explanation:

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