Question

a 4.50 - volt personal stereo uses 1950 joules of electrical energy in one hour. what is the electrical resistance of the personal stereo? 96.3 ohms 0.623 ohms 433 ohms 37.4 ohms

Explanation:

Step1: Calculate the power

Power \( P=\frac{W}{t} \), where \( W = 1950\ J \) and \( t=3600\ s \) (since 1 hour = 3600 seconds).
\( P=\frac{1950}{3600}\approx0.542\ W \)

Step2: Use the formula \( P=\frac{V^{2}}{R} \) to find resistance \( R \)

Rearrange the formula to \( R = \frac{V^{2}}{P} \), where \( V = 4.50\ V \) and \( P\approx0.542\ W \)
\( R=\frac{4.50^{2}}{0.542}=\frac{20.25}{0.542}\approx37.4\ \Omega \)

Answer:

37.4 Ohms