NEET Sample Paper NEET Sample Test Paper-40

  • question_answer
    A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the Efficiency of the transformer is approximately:

    A)  30%

    B)  50%

    C)  90%

    D)  10%

    Correct Answer: C

    Solution :

     The efficiency of transformer \[\text{=}\,\frac{\text{Energy}\,\text{obtained}\,\text{from}\,\text{the}\,\text{secondary}\,\text{coil}}{\text{Energy}\,\text{given}\,\text{to}\,\text{the}\,\text{primary}\,\text{coil}}\] or \[\eta \,\text{=}\,\frac{\text{Output}\,\text{power}}{\text{Input}\,\text{power}}\] or \[\eta =\frac{{{V}_{s}}{{I}_{s}}}{{{V}_{p}}{{I}_{p}}}\] Given, \[{{V}_{s}}{{I}_{s}}=1000\,W,\,{{V}_{p}}=200\,V,{{I}_{p}}=0.5\,A\] Hence, \[\eta =\frac{100}{220\times 0.5}0.90=90%\]


You need to login to perform this action.
You will be redirected in 3 sec spinner