QQuestion
Bulb A rated 160 W, 40 V and Bulb B rated 40 W, 40 V are connected as shown in the diagram.
(a) Calculate the ratio V1 : V2.
(b) If bulb A fuses, the current in the circuit remains the same. State True or False.
✓Answer
(a) Resistance of bulb A = \frac{40^2}{160} = 10 Ω.
Resistance of bulb B = \frac{40^2}{40} = 40 Ω.
Since the bulbs are in series, potential difference divides in the ratio of resistance.
V1 : V2 = 10 : 40 = 1 : 4.
(b) False
Explanation:
If bulb A fuses, the circuit becomes open and the current becomes zero.
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