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Question

A bulb is connected across a battery of 10 V for 20 seconds. If a current of 2 A flows through it, calculate the heat energy generated by the bulb.

This question was previously asked in
RRB NTPC 2024 Undergraduate CBT 1 Question Paper (29-Aug-2025) (Shift 1)
The correct answer is

400 J

The heat energy generated by the bulb can be calculated using the formula for electrical power and energy:

Power (P) = Voltage (V) × Current (I)

Given:

  • Voltage (V) = 10 V
  • Current (I) = 2 A

Therefore, the power consumed by the bulb is:

P = 10 V × 2 A = 20 W

Energy (E) = Power (P) × Time (t)

Given:

  • Power (P) = 20 W
  • Time (t) = 20 s

Therefore, the heat energy generated by the bulb is:

E = 20 W × 20 s = 400 J

Thus, the correct answer is 400 J.

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