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Question
A torch bulb is rated at 3 V and 600 mA. Calculate it’s
- power
- resistance
- energy consumed if it is used for 4 hours.
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Solution
- V = 3V and I = 600 mA = 600 × 10-3 A
(a) Power (P) = VI
= 3 × 600 × 10-3
= 1800 × 10-3
= 1.8 W (or) watt. - Resistance (R) =
\(\frac{\mathrm{V}}{\mathrm{I}}\) = \(\frac{3}{600 \times 10^{-3}}\) = 5 Ω. - Power (P) = 1.8 W and
Time = 4 hours = 4 × 60 × 60 = 14400 second
Energy consumed E = P × t = 1.8 × 14400 = 25920 joules
E = 25.9 KJ.
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