When a potential difference Is applied to a light bulb (i.e. when the light is t

Question

When a potential difference Is applied to a light bulb (i.e. when the light is turned on) the light bulb's tungsten filament is initially cold, but it heats rapidly. How does the Initial current through the light bulb compare to the current through the light bulb once it has been on for a few minutes? Which one of the following options is not a valid unit for energy? The potential difference across a resistor is 9 V and it carries a current of 1 A. Calculate the energy delivered to the resistor in the time of 1 minute.

Explanation / Answer

1)The resistance of the tungsten increases with the increase in temperature. Thus, initially the current through the light bulb is large compared to the current through it after a few minutes.

2)Joule/ second is not a valid unit because it is unit for “ POWER”

3)The energy delivered is:

E=VIt=(9V)(1A)(60 s)=540 J

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