Question

60 volt bulb is provided with 240 volts potential difference then resistance of the bulb equal to

Answer 1

Answer:

Maximum current flowing through a bulb I=

V

P

For bulb of 40 W :

Maximum current I

1

=

240

40

=0.167 A

Resistance of bulb, R

1

=

40

(240)

2

=1440Ω

For bulb of 60 W :

Maximum current I

2

=

240

60

=0.25 A

Resistance of bulb, R

2

=

60

(240)

2

=960Ω

Now both the bulbs are connected in series :

Total resistance of the circuit R=960+1440=2400Ω

Thus current flowing through the circuit I=

2400

420

=0.175 A

As current flowing through the circuit is greater than the maximum current that flows through bulb of 40 W, thus this bulb will not work but bulb of 60 W does.