Class 12 Physics
CBSE and UP Board
Current Electricity
NCERT Solutions for Class 12 Physics Chapter 3
Chapter-3 Exercise 3
A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?
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Emf of the battery, E = 10 V
Internal resistance of the battery, r = 3fi
Current in the circuit, I = 0.5 A
Resistance of the resistor = R
The relation for current using Ohm’s law is,
I = E/(R+r)
R+r =E/I= 10/0.5 =20 Ω
Therefore ,R =20-3 = 17 Ω
Terminal voltage of the resistor = V
According to Ohm’s law,
V = IR = 0.5 x 17 = 8.5 V
Therefore, the resistance of the resistor is 17 Q and the terminal voltage is 8.5 V.