Question

A filament lamp is rated 100 W and 240 V. Find
(A)the current flowing in the lamp
(B)the resistance of the lamp filament and
(C)the energy produced by the lamp in 1.5 hours.

Answer 1

Power = 100W

Voltage = 240V

Resistance = ?

Power $=\frac{V^2}{R}$

$=\frac{V^2}{P}$

$=\frac{240\times 240}{100}$

$=576\Omega$

Current = $\frac{power}{voltage}$

$=\frac{100}{240}$

$=\frac{5A}{12}$

Power $=\frac{energy}{time}$

$100=\frac{energy}{1.5\times 3600}$

Energy $=100\times 3600\times \frac{1.5}{10}$

= 540000Joules