CONDITION:-

If a torch emits a photon with high frequency( high energy "E")

another torch emits a photon with very low frequency ( very low energy "e").

 

Question:-

Which torch will get bigger thrust in opposite direction?

 

My Perspective:-

According to newtons 3rd law both should get equal thrust because speed of light is constant no matter what the energy.

 

 

<<<<Please answer>>>>>

The momentum of a photon is E/c, so the higher energy photon will carry more momentum and give a larger impulse. That's for a single photon. Force is impulse per unit time, so force is E/c multiplied by the number of photons/sec being emitted, which is simply power/time. So for a continuously emitting source, the wavelength does not matter; the power is what is important. i.e. a source of a given power gives the same thrust, regardless of wavelength.

All Right! Thats gona help.

Thanks alot.