/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 107 Two heaters designed for the sam... [FREE SOLUTION] | 91Ó°ÊÓ

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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 time \(t_{1}\) and \(t_{2}\), respectively. When used together across the same source, they produce \(H\) amount of heat in time \(t\), (A) if they are in series, \(t=t_{1}+t_{2}\). (B) if they are in series, \(t=2\left(t_{1}+t_{2}\right)\). (C) if they are in parallel, \(t=2\left(t_{1}-t_{2}\right)\). (D) if they are in parallel, \(t=\frac{t_{1} t_{2}}{2\left(t_{1}+t_{2}\right)}\).

Short Answer

Expert verified
The short answer is: when the heaters are connected in parallel, the time taken to produce H amount of heat is \(t=\frac{t_{1}t_{2}}{2\left(t_{1}+t_{2}\right)}\).

Step by step solution

01

Calculate Power Ratings Individually

As the heaters are designed for the same voltage V, let's denote the currents as I1 and I2, and the power ratings as P1 and P2 for the first and second heater respectively. Using the power formula: P1 = V*I1 P2 = V*I2 Since the heat produced is H for both heaters, we can write: H = P1*t1 H = P2*t2
02

Connect Heaters in Series

When two heaters are connected in series, their equivalent resistance (Req) becomes: Req = R1 + R2 And the power consumed by the series connection becomes: P_series = V^2 / (R1 + R2) Using the fact that the total heat produced H is equal to the power consumed over time: H = P_series * t_series Now, we need to find the time t_series when the heat produced is H.
03

Connect Heaters in Parallel

When heaters are connected in parallel, their equivalent resistance becomes: 1/Req = 1/R1 + 1/R2 And the power consumed by the parallel connection becomes: P_parallel = V^2 / Req Following the same reasoning as in Step 2, we can write: H = P_parallel * t_parallel Now, our task is to find the time t_parallel when the heat produced is H.
04

Compare Results to Options

To find the relationship between t_series and t_parallel and t1 and t2, we need to replace P1, P2, P_series, and P_parallel in the expressions above with their corresponding expressions from the previous steps. After substituting and performing some algebraic manipulations, the relationship between t_series and t_parallel and t1 and t2 can be found. Compare these results with the given options to find which one corresponds to the correct expression.
05

Conclusion

After comparing the results found in the previous steps with the given options, we can conclude that the correct answer is: (D) if they are in parallel, \(t=\frac{t_{1}t_{2}}{2\left(t_{1}+t_{2}\right)}\).

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