Question

An electric bulb is marked as 240 v ,60 w .the resiatance of its filament is

Answer 1

P = V^2 / R
60 = (240)^2 / R
R = 57600 / 60
R = 960 ohm

Answer 2

p=60w
v=240volt
r=?
$we \: know \: that \\p = \frac{ {v}^{2} }{r} \\ p = \frac{ {240}^{2} }{r} \\ r = \frac{57600}{60} \\ r = 960ohm$