I am about to toss this book off the window

[flyingpig]

Homework Statement

A 100W lightbulb connected to a 120V source experiences a voltage surge that produces 140V for a moment. By what percentage does its power output increase? Assume its resistance does not change

The Attempt at a Solution

(1) P_0 = C\Delta V_0 ^2

(2) P = C\Delta V^2

Note that C is a constant (the resistance)

Divide (1) by (2)

\frac{P_0}{P} = (\frac{\Delta V_0}{\Delta V})^2

Plugging the numbers I get 1.36111...

Multiply it by 100 I get 136.11%

Now, the book says 36.11%

Why...?

 

[Mandeep Deka]

1. Behave yourself. You should give a apt title to your question.
2. You have been asked to calculate the percentage increase in power output. It is the percentage ratio of increase in power output to the initial power.

 

[supratim1]

increase = final - initial = 36.11

so required percentage = 36.11%