Question

In a factory, 220V bulbs are connected in parallel and each bulb takes a current of 0.1A at 220V.  Calculate the combined resistance of all the bulbs and current drawn from the source

Answer 1

let R1 and R2 =?

let V1=220V and

V2=220V

I=0.1A

SO, WE KNOW THAT

V=IR,

SO, R=V/I

Now calculate the R1 and R2,

R1= V1/I

=220/0.1

=2200 ohm

R2= V2/I

=220/0.1

=2200 ohm

now calculating combined resistance in parallel combination:

1/eff Resistance= 1/R1+1/R2

= 1/2200+1/2200

=2/2200

=1/1100

so, eff Resistance become 1100 ohm.

Answer 2

V=220 v

I1=0.1A

I2=0.1A

Req=?

for each resistance ,R=V/I1

R1=220/0.1

=2200ohm

similarly

R2=220/0.1

=2200ohm

1/Req=1/R1+1/R2

=1/2200+1/2200

take lcm

=1+1/2200

=2/2200

1/Req=2/2200

reciprocal

Req=2200/2

Req=1100ohm