Assertion : An electric bulb becomes dim, when the electric heater in parallel circuit is switched on.
Reason : Dimness decreases after sometime.
AIIMS 2008, Easy
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The electric power of a heater is more than that of a bulb. As $P\, \propto \,\frac{1}{R}$, the resistance of heater is less than that of the electric bulb. When a heater connected in parallel to the bulb is switched on, it draws more current due to its lesser resistance, consequently, the current through the bulb decreases and so it becomes dim. When the heater coil becomes sufficient hot, its resistance becomes more and hence it draws a little lesser current. Consequently, the current through the electric bulb recovers.
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