PHYS208 Fundamentals of Physics II
Solution to Ch. 27, 62P:
a. 8.5% drop.
Your may use the formula P=V^2/R and directly calculate each power and compute the fractional difference.
You may also notice that delta P/P = 2 delta V/V can approximate the power drop as being twice the voltage drop (in percentages).
b. Denominator in power formula above also decreases with lowered voltage,
so power drop is not as large as expected in (a).
Thanks to James Durbano for pointing out the numerical error in my first posting of this answer.
Last updated Sept. 13, 1997.
Copyright George Watson, Univ. of Delaware, 1997.