What is the maximum voltage that can be applied across a $3.9$-$\textrm{k}\Omega$ resistor rated at $\dfrac{1}{4}$ watt?

VIDEO TRANSCRIPT

This is Giancoli Answers with Mr. Dychko. We can rearrange this formula to solve for V by multiplying both sides by resistance R and on the left side you have R P and on the right side you have V squared and switch the sides around, take the square root of both sides and you get V is square root R P. So, the maximum voltage you could apply across this resistor would be when it has its maximum of one quarter watts of power output. So thats 0.25 watts and the resistance is 3.9 times ten to three ohms and this makes 31 volts the maximum possible voltage.