A potentiometer wire of length 300 cm is connected in series with a resistance 780 Ω and a standard cell of emf 4 V. A constant current flows through potentiometer wire. The length of the null point for cell of emf 20 mV is found to be 60 cm. The resistance of the potentiometer wire is ______ Ω.
← JEE Main 2022 · 26 Jul · Shift 2
PhysicsInteger+4 / -1Question 59 of 90
JEE Main 2022 · 26 Jul · Shift 2, Physics question 59
Answer and worked solution
Official answer: 20
Gradient. 20 mV over 60 cm means 100 mV across the 300 cm wire.
Divider. , so and Ω.
Answer: 20
Topics:Potentiometer