Question

the electrical resistance of 100w, 240v bulb will be​

Answer 1

Since P = Vi, where P = Power, V = Potential Difference and i = Electric Current.

100 W = 240 V × i

i = 100/240 A

i = 5/12 A

Since R = V/i, where R = Resistance, V = Potential Difference and i = Electric Current.

R = 240 V / ( 5/12 A )

R = 240 × 12/5 Ohm

R = 48 × 12 Ohm

R = 576 Ω

Concept :

• Remember formula of Power and,
• Remember formula of Resistance.