Physics
An electric bulb is rated '250 W, 230 V'. Calculate
(i) the energy consumed in one hour, and
(ii) the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains?
Current Electricity
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Answer
(i) Given,
Power (P) = 250 W
Voltage (V) = 230 V
Time (t) = 1 h = 3600 sec
Energy (E) = ?
From relation,
E = P × t
Substituting the values in the formula above, we get,
E = 250 x 3600 = 9 x 105 J
Hence, energy consumed in one hour = 9 x 105 J
(ii) Let t be the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains
P = 1.0 kWh = 1000 Wh
Substituting the value in the formula, we get,
1000 = 250 x t
⇒ t = 1000 / 250 = 4 h
Hence, time = 4 h
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