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A circuit consists of a 6 Ω and 15 Ω resistor connected in parallel and an unknown resistor R, in series. An ammeter, a high-resistance voltmeter, a closed switch and battery are connected. The resistance of the battery and wires can be ignored.
The total power dissipated in the parallel part of the circuit is 50 W.
1 Define the term power.
2 Calculate the effective resistance of the parallel combination.
3 Calculate the potential difference across the resistors in parallel.
4 Calculate the current through resistor R.
in Physics
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## 1 Answer

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1 Power is the rate, per unit time, at which work is done or energy is transfered.

2  Apply parallel rule of resistors,

1/R// = 1/R1 + 1/R2
1/R//  = 1/6 + 1/15

Hence,  R// = 4,29 Ω

3  Apply parallel rule of voltage,

P= V^2/R

50= V^2/4.29

Therefore V= 14.65 V

4  Apply series rule,

P=VI

50 = 14.65 x I

I = 3.41 A
by Diamond (42,256 points)

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