BCECE Medical BCECE Medical Solved Papers-2005

  • question_answer
    Two bulbs 25 W; 220 V and 100 W, 220 V are given. Which has higher resistance?

    A)  25 W bulb

    B)  100 W bulb

    C)  Both bulbs will have equal resistance

    D)  Resistance of bulbs cannot be compared

    Correct Answer: A

    Solution :

    Power in electric bulb                 \[P=\frac{{{V}^{2}}}{R}\] So, resistance of electric bulb                 \[R=\frac{{{V}^{2}}}{P}\] Given,   \[{{P}_{1}}=25\,\,W,\,\,{{P}_{2}}=100\,W\],                 \[{{V}_{1}}={{V}_{2}}=220\] volt Therefore, for same potential difference V                 \[R\propto \frac{1}{P}\] Thus, we observe that for minimum power, resistance will be maximum and vice-versa. Hence, resistance of 25 W bulb is maximum and 100 W bulb is minimum.


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