Question

Q.9 - Two lamps, one rated 100 W :220 V and the other 60 W; 220 V are
connected in parallel to electric mains supply. Find the current drawn by
the two lamps from the line, if the supply voltage is 220 V.​

Answer 1

Answer:

ANSWER

From Joule's Law of heating,

P=V

2

/R

For first lamp,

R

1

=220

2

/100

For second lamp,

R

2

=220

2

/60

When they are connected in parallel,

R

eq

1

=

R

1

1

+

R

2

1

=

220

2

/100

1

+

220

2

/60

1

⟹R

eq

=220

2

/160

From Ohm's Law,

V=IR

eq

220=

160

220

2

I

I=0.73 A