A battery is conected to 3 identical lamps P,Q and R as shown. Initially the switch S is kept open and lamps P and Q glow with some brightness. Then switch S is closed. How will the brightness of the lamps P and Q change ? Justify.

Asked by renukanancyqueen2015 | 18th Sep, 2015, 04:15: PM

Expert Answer:

When the switched is closed, bulb Q and R are parallel to each other. The combined resistance of a parallel combination is less than the individual resistance.
So, the whole circuit consists of P in series with the parallel combination of Q and R. Thus, the bulb P will be brighter than the Q and R.

Answered by Yashvanti Jain | 20th Sep, 2015, 07:59: PM

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