Question

yanina is drying her hair for the dance tonight. the hair dryer has a total input of 1300j energy. 650j of energy is used to dry her hair. what is the percentage efficiency of the hair dryer? 200% 50% 2% 0.5%

Explanation:

Step1: Recall the formula for efficiency

Efficiency ($\eta$) is given by the formula $\eta=\frac{\text{Useful energy output}}{\text{Total energy input}}\times100\%$.

Step2: Substitute the given values into the formula

Here, the useful energy output is $650\space J$ and the total energy input is $1300\space J$. So, $\eta = \frac{650}{1300}\times100\%$.

Step3: Calculate the value

$\frac{650}{1300}=0.5$, and $0.5\times100\% = 50\%$.

Answer:

B. 50%