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electricity

How the power output of the lamp is related to its brightness?
Original post by MohdShihaab
How the power output of the lamp is related to its brightness?


You have to assume that the brightness is directly proportional to its power output, which is a fair assumption. When the power output increases, the brightness increases.
Reply 2
Original post by AHappyStudent
You have to assume that the brightness is directly proportional to its power output, which is a fair assumption. When the power output increases, the brightness increases.

i want the answer of that question in full physics theory as it is part of my assessment?
Original post by MohdShihaab
i want the answer of that question in full physics theory as it is part of my assessment?


Okay. I suppose that you could go into some detail. Light is made up of photons (forget about the wave stuff for this, it's a bit weird). The frequency of light is related by the equation E = hf, where E is the energy of a photon in joules, h is plank's constant (roughly 6.63 * 10^ -34) and f is the frequency of the light. Frequency will remain constant if we're assuming that the colour of light does not change with power output.

So, if you increase the power output, more photons of energy E can be emitted per second, which is effectively the brightness of the power source.

Edit: The power output of light of a source is called it's luminosity, which is related to brightness which is the luminosity of an object in a certain area. The above bit is still useful though as you can calculate the photons per second emitted by the source.
(edited 6 years ago)
Well have is power? P=IV. As the above poster said, you need to assume it is directly proportional to the brightness, and the above equation helps make sense of that. If the current through the load increases, what exactly is happening? More charge is passing through each second right? How is that going to effect the brightness?

This sounds like a homework question really. You'll learn nothing by us giving you the answer. Best to research it yourself now that you've been given a starting point.
Original post by MohdShihaab
i want the answer of that question in full physics theory as it is part of my assessment?


As you say, it's part ot YOUR assessment. Why would you think it to be acceptable for someone to write it for you?

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