Question

why the light is bright​

Answer 1

Answer:

In this model, the photoreceptors in your eye undergo chemical reactions as a result of absorbing photons. The more photons absorbed per second, the brighter the light appears. Brightness is just the number of photons per second hitting your eye - all the other properties of the light are the same.

Answer 2

Answer:

Brightness is purely due to the amount of photons entering your eye. Oh, so every photon of a certain frequency has the same amount of energy but the energy of photons of different wavelengths or frequency.