Physics - EMI/AC Question with Solution | TestHub

Mains voltage is$V=\text{240 }\mathrm{V}$and

mains current is$I=0.7 \mathrm{A}$

input power will be$P_{\text{input}}=\text{240}\times \text{0.7}=\text{168 }\mathrm{W}$

But output power is given as$P_{\text{output}}=\text{140 }\mathrm{W}$

Therefore efficiency$=\frac{\text{output}}{\text{input}}\times \text{100}\text{\%}=\text{83.33}\text{\%}$