MCQ
A motor operating on 100 V draws a current of 1 A . If the efficiency of the motor is $91.6 \%$, then the loss of power in units of $\mathrm{cal} / \mathrm{s}$ is
- A4
- B8.4
- C2
- D6.2
✓
Answer
C. 2
$P_{\text {input }}=V i=100 \mathrm{~W}$
$\eta=\frac{P_{\text {out }}}{P_{\text {input }}}=0.916$
$\mathrm{P}_{\text {out }}=91.6 \mathrm{~W}$
Loss $=100-91.6=8.4 \mathrm{~J} / \mathrm{s}=2 \mathrm{cal} / \mathrm{s}$
$P_{\text {input }}=V i=100 \mathrm{~W}$
$\eta=\frac{P_{\text {out }}}{P_{\text {input }}}=0.916$
$\mathrm{P}_{\text {out }}=91.6 \mathrm{~W}$
Loss $=100-91.6=8.4 \mathrm{~J} / \mathrm{s}=2 \mathrm{cal} / \mathrm{s}$
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