KCET2020PhysicsCurrent Electricity
A potentiometer has a uniform wire of length 5 ~m . A battery of emf 10 ~V and negligible internal resistance is connected between its ends. A secondary cell connected to the circuit gives balancing length at 200 ~cm . The emf of the secondary cell is
Options
- A4 ~V
- B6 ~V
- C2 ~V
- D8 ~V
Correct answer
A. 4 ~V
Step-by-step solution
Given, length of potentiometer wire l=5 ~m emf of battery, E=10 ~V Potential gradient across the potentiometer wire, K= E l = 10 5 =2 Vm ⁻¹ When secondary cell is connected to the circuit of potentiometer, then balancing length, l₁=200 ~cm =2 ~m emf of the secondary cell, E_ s =K l₁=2 2=4 ~V