Ok so first you need to figure out the energy of ONE photon with that wavelength. Using E=hc/lambda, you get E= 1.99 * 10^-20 J/photon. Now, how many photons do you need to add up to get to one kilojoule=1000 joules? 1000J / (1.99 * 10^-20 J/photon) = approximately 5 * 10^22 photons
hope this helps
Electromagnetic wave travels faster through air than metal.
Option A
<u>Explanation:</u>
There are different kinds of wave energy. The most significant are electromagnetic and mechanical waves. The mechanical waves propagate through the medium by transfer of energy by vibrating of particles in medium.
So, the more number of particles present in the medium, the more fast the mechanical wave can propagate. So the mechanical waves travel faster in metals consisting of more number of free charge carriers. But electromagnetic waves does not need any of the medium to propagate. So it can travel faster in air than in metals.
Light travels in a straight line as a wave. It does not require any medium or material to travel like sound waves which means it can travel in vacuum.The speed of the light from the special theory of relativity is a constant value of 38x10^8m/second
From the chemical equation given, one mole of CH4 yields two moles of water (H2O). If all the methane gas that is 8.9 L is combusted then the volume of water produced is the number of moles H2O times the volume of the methane gas used up, that is 8.9 L × 2 = 17.8 L of water produced.
