The consumption of energy by 60-watt bulb in 2 seconds is:
Correct answer: B. 120 J
- A. 20 J
- B. 120 J
- C. 30 J
- D. 0.02 J
Explanation
The energy consumed by a 60-watt bulb in 2 seconds can be calculated using the power formula: P = E/t. Here, P is the power in watts (60 W), E is the energy in joules, and t is the time in seconds (2 s). Rearranging the formula gives E = P × t, which results in E = 60 × 2 = 120 J. Option B is correct. The other options provide incorrect values due to miscalculation or misunderstanding of the formula.
This question appeared on the UHS MDCAT 2010 paper, which you can sit online with every answer explained.
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About Power
Power is the rate at which work is done or energy is transferred, with average power calculated over a time interval and instantaneous power found from P = Fv when force and velocity are aligned. Work includes units, mechanical efficiency, and the distinction between power and total work or energy.
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