TransWikia.com

Is it resistance of filament or current thorugh it which determines brightness of bulb?

Physics Asked on October 15, 2020

SO brightness of bulb. Does it depend on the resistance or current in it?
I have two bulbs keeping everything same except resistance. So

Bulb A – high resistance

Bulb B – Low resistance

which bulb will glow brighter?

2 Answers

It's the power dissipated by the Joule heating of the element that determines the brightness - remember that an incandescent bulb operates on the principle of thermal radiation.

$$P = frac{V^2}{R}$$

so that, in turn, depends on the voltage and the resistance of the element. Most likely it's a bit more complicated than that since the resistance will go up as it heats up. But this is good enough for the general idea. A more resistive bulb will dissipate less power, and so be dimmer, for a given applied voltage, and increasing the voltage dramatically increases the power, as can be see by the square factor. So the less-resisting bulb is going to be the brighter one if you apply the same voltage to both. For current, it's

$$P = IV$$

so goes up linearly with increase in either one, but current is related to voltage with resistance, so you in practice don't modulate voltage and current independently (unless you could somehow modulate the resistance of the filament!).

Answered by The_Sympathizer on October 15, 2020

Brightness of a bulb depends on the power it consumes.the more power it consumes the brighter it should flow .

Now power dissipated depends on both current and resistance .

                 Power = I²R

          

Answered by Protein on October 15, 2020

Add your own answers!

Ask a Question

Get help from others!

© 2024 TransWikia.com. All rights reserved. Sites we Love: PCI Database, UKBizDB, Menu Kuliner, Sharing RPP