Question

A potentiometer wire AB is 100 cm long and has a total resistance of 10 ohm. If the galvanometer shows zero deflection at the position C, then
10V
40 cm
с
A
find the value of unknown resistance R.
SV r=112
HHG
R​

Answer 1

Answer:

Answer: The correct answer is 0.16 A.

Explanation:

The expression of the current is as follows;

I=\frac{E}{R+R'}I=

R+R

′

E

Here, I is the current,R' is the internal resistance, R is the resistance of the wire and E is the EMF of the cell.

Put R= 10 ohm , R'= 40 ohm and E= 2 V.

I=\frac{2}{10+40}I=

10+40

2

I=0.04 AI=0.04A

Calculate the resistance of 40 cm length of the potentiometer.

R= \frac{10}{100}(40)R=

100

10

(40)

R= 4 ohmR=4ohm

Calculate the unknown emf e by using Ohm's law.

e=V=IR

Put R= 4 ohm and I= 0.04 A.

e=V= (0.04)(4)

e=V= 0.16 A

Therefore, the correct value of e is 0.16 A.