waec model questions vol1 2021 physics
Objective • Question 21
Question 21
WAEC_MODEL_QUESTIONS_VOL1
•
2021
A battery of unknown emf E and internal resistance r is connected to a load resistor. When a 10 Ω resistor is connected, the terminal voltage is 6 V. When a 20 Ω resistor is connected, the terminal voltage is 8 V. Determine (i) the emf and internal resistance of the battery, (ii) the value of external resistance that will make the power delivered to the load maximum, and (iii) the maximum power transferred to the load.
Answer Options
Correct Answer
A.
E = 12 V; r = 10 Ω; R = 10 Ω; Pmax = 3.6 W
B.
E = 10 V; r = 12 Ω; R = 12 Ω; Pmax = 2.5 W
C.
E = 14 V; r = 8 Ω; R = 8 Ω; Pmax = 4.9 W
D.
E = 12 V; r = 8 Ω; R = 8 Ω; Pmax = 4.8 W
Correct Answer
A
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