Question

An electric lamp rated 200w,240v operates for a time interval of 5 minutes calculate

(a)resistance of the lamp

(b)current flowing through the lamp

(c)electrical energy of the lamp

Answer 1

Given:

$$U=240V; P=200W; t=5min=300s.$$

Find:

a) R-resistance of lamp;

b) I- current flowing through the lamp;

c) E-electrical energy of the lamp.

Solution:

a) $P=UI=U^2/R; R=P/U^2;$

$R=200W/(240V)^2=0.00347\Omega=3.47 m\Omega.$

b) $I=P/U=200W/240V=0.833A.$

c) $E=Pt=200W*300s=60000 J=60 kJ.$

Answer:

a) $R=3.47 m\Omega;$

b) $I=0.833 A;$

c) $E=60 kJ.$