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Two heaters designed for the same voltage V have different power ratings. When connected individually across a source of voltage V, they produce H amount of heat each in times t1 and t2 respectively. When used together across the same source, they produce H amount of heat in time t.(a) If they are in series, t = t1 + t2.(b) If they are in series, t = 2(t1 + t2).(c) If they are in parallel, t = t1t2 / (t1 + t2).(d) If they are in parallel, t = t1t2 / 2(t1 + t2). |
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Answer» Correct Answer is: (a, c) Let R1 and R2 be the resistances of the two heaters. Let H be the heat produced. ∴ H = (V2/R1) t1 = (V2/R2) t2. When used in series, H = (V2/R1 + R2) t. When used in parallel, H = (V2/R1 + V2/R2) t. |
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