Question

two bulbs rated at voltage V for 80W and 100W and connected in serious and varying voltage is applied across it.when the voltage is increased and reaches 360V one of the bulb glows at its rated power .Then the voltage rating V is?​

Answer 1

Explanation:

R

1

=

P

v

2

=

25

200

2

=1600Ω

R

2

=

100

200

2

=400Ω

When both bulbs are connected in series

V

1

=440×

R

1

+R

2

R

1

=440×

1600+400

1600

=352V;V

2

=440×

2500

400

=88V

Voltage across 25W bulb is greater than specified voltage, hence it will fuse

solution