NEETPhysicsCurrent Electricity
A battery of EMF 18 V and internal resistance 2 is connected in a single closed loop with another battery of EMF 6 V and internal resistance 1 . The two batteries are connected in opposition. An external resistor of 9 is also connected in series in the loop. What is the potential difference across the terminals of the 6 V battery?
Options
- A5 V
- B7 V
- C16 V
- D6 V
Correct answer
B. 7 V
Step-by-step solution
The two batteries are connected in opposition, so their net EMF is the difference between their individual EMFs: E_ net = 18 V - 6 V = 12 V . The total resistance in the circuit is the sum of the external resistance and the internal resistances of both batteries: R_ net = 9 + 2 + 1 = 12 . The current in the circuit is: I = E_ net R_ net = 12 12 = 1 A . Since the 18 V battery dominates, the current flows out of its positive terminal and enters the positive terminal of the 6 V battery. This means the 6 V battery is b