Imagine you have a light bulb of 1 watt power. Then, is 1 watt defined as •1 joule of electric energy transformed to 1 joule of light energy in 1 sec? •what exactly is meant by 'consumption' of energy in a light bulb? What has it to do with watts?
6
-
$\begingroup$ An incandescent light bulb is a resistor that gets hot enough that the black body emission has lots of visible light. Most is not in the visible. $\endgroup$– Jon CusterCommented 2 days ago
-
1$\begingroup$ 1 Joule/sec of energy is emitted by the 1 W bulb, but much of that energy will be in the form of heat. $\endgroup$– David WhiteCommented 2 days ago
-
$\begingroup$ How much energy in photons is getting emitted. $\endgroup$– CPlusCommented 2 days ago
-
1$\begingroup$ @DavidWhite, A "1W" laser emits 1W of optical energy, but a "1W" light bulb consumes 1W of electrical energy and emits significantly less optical energy. To make matters even worse, they're still marketing "60W equivalent" light bulbs (and other sizes too) that emit as much light as a 60W incandescent bulb used to do, but which only consume maybe 8 or 10W of electrical energy. $\endgroup$– Solomon SlowCommented 2 days ago
-
$\begingroup$ @SolomonSlow this isn't meant to be criticism. However, using wording implying that energy is "consumed" may confuse physics novices regarding conservation of energy arguments. $\endgroup$– David WhiteCommented 2 days ago
|
Show 1 more comment
1 Answer
$\begingroup$
$\endgroup$
For an appliance, power is the energy consumed by it in one second. Here in case of bulb, consumption means energy taken simply in form of electrical energy. Suppose in 1 second, 1 joule of energy is used then the energy released should also be 1 joule. The energy released maybe in any form (heat,light kinetic,etc.) So saying that 1 joule energy released would be the light energy is wrong. The 1 joule energy released is distributed in many forms of energy not just light energy.