Question

A dc main supply of emf 220 v is connected across a storage battery of emf 200 v through a resistance of 1. The battery terminals are connected to an external resistance r.The minimum value of r so that a current passes through the battery to charge it is

Answer 1

I = v / r
1) I = 220/ 1 * 200
I = 20

Answer 2

Hey dear,

◆ Answer-
R = 11 ohm

◆ Explaination-
# Given-
r = 1 ohm
E = 200 V
V = 220 V

# Solution-
Let R be minimum value of resistance required.

Resistance of battery is calculated by-
r = R (V-E) / V
R = rV / (V-E)
R = 1 × 220 / (220-200)
R = 220/20
R = 11 ohm

Therefore, minimum value of resistance required so that current passes through battery to charge it is 11 ohm.

Hope it helps...