KCET 2015 Physics Solved Paper

Given, transformer lights 100 W – 100 V lamp; input voltage = 220 V; input current = 0.5 A
Therefore, efficiency η=

‌ Output power

Input power

×100
Here, output power = 100 W
Input power = Input voltage × Input current =220×0.5=110W
Thus, η=‌

100

110

×100=90%