Physics

Problem

A fixed resistor is connected across a steady direct-current source so that it carries a constant current. a. (i) State the definition of electrical power. b. (ii) Starting from the work done in moving charge through a potential difference, derive the expression

P = VI

for the power supplied to the resistor. c. (iii) Using Ohm’s law, show that

P = I^{2}R = \dfrac{V^{2}}{R}

. d. (iv) The resistor has resistance

25\,\Omega

and carries a current of

2.0\,\text{A}

for

5.0\,\text{min}

. Calculate the electrical energy converted into heat during this interval. Express your answer both in joule and in kilowatt-hour.

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