Current Electricity | Practice MCQs Physics for Mdcat | mosaicbro.com

Current Electricity | Practice MCQs Physics for Mdcat

7 of 85 questions (Page 10 of 13)

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64 The unit of electrical energy is:
Correct Answer: A
Explanation: Kilowatt-hour (kWh) is the commercial unit of electrical energy.
65 Amount of energy delivered by the current in one hour when it supplies energy at the rate of 1000 J/s is known as:
Correct Answer: B
Explanation: $1000J/s = 1kW$; over 1 hour, energy = $1kWh$.
66 1 Kwh = ______:
Correct Answer: A
Explanation: $1kWh = 1000W × 3600s = 3.6 × 10^6J$.
67 A 1000 watt heater operates on a 220 volt line for one hour. The current passing through heater is:
Correct Answer: D
Explanation: $I = \frac{P}{V} = \frac{1000W}{220V} ≈ 4.5A$.
68 A 100 watt bulb is operated by 200 volt, the current flowing through the bulb is:
Correct Answer: B
Explanation: $I = \frac{P}{V} = \frac{100W}{200V} = 0.5A$.
69 The resistance of 60 watt bulb in a 120 volt line is:
Correct Answer: C
Explanation: $R = \frac{V^2}{P} = \frac{(120V)^2}{60W} = 240Ω$.
70 The devices which can maintain a potential difference between points to which they are attached are known as:
Correct Answer: B
Explanation: Sources of emf (e.g., batteries) maintain potential differences.
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