Question

Calculate the current through a 60 W lamp rated for
250 V. If the line voltage falls to 200 V, how is the
power consumed by the lamp affected ?
​

Answer 1

To find:- The electric current when the voltage in the same circuit falls from 250W to 200W

SOLUTION:-

As we know that the resistance of a circut never changes (even after changing the other values).

So we will first find out the Resistance of he circuit.

P = V^2 / R

Putting the given values,

=> 60 = 250 X 250 / R

=> R = 250 X 250 / 60 ohms .....(1)

(WE WILL NOT SIMPLIFY THE EQUATION NOW)

Now, since we know the value resistance

Therfore, we can apply the ohm's formula with the changed Voltage i.e 200 W

I = V / R

{ PUTTING THE VALUE OF V AND R}

I = 200 / 250 X 250 / 60

I = 200 X 60 / 250 X 250

I = 0.192 Ampere

hope it helps!!

solved only by me, no help taken.