Answer:
To solve this problem, we need to use the formula E = hc/λ, where E is the energy of the photon, h is Planck's constant, c is the speed of light, and λ is the wavelength. But wait, what are these symbols? How do we know what values to use? And why do we divide by the wavelength? This is so confusing!
Well, let's try to understand. Planck's constant is a very small number that relates the energy and frequency of a photon. It has a value of 6.626 x 10^-34 J s. The speed of light is how fast light travels in a vacuum. It has a value of 3 x 10^8 m/s. The wavelength is the distance between two consecutive peaks or troughs of a wave. It is measured in meters or nanometers or micrometers or whatever unit you like.
So, to find the energy of a photon, we need to multiply Planck's constant and the speed of light, and then divide by the wavelength. But why? Well, it has something to do with the wave-particle duality of light. Light can behave like a wave or a particle, depending on how we observe it. When we measure the wavelength, we are treating light as a wave. When we measure the energy, we are treating light as a particle. The formula E = hc/λ is a way of converting between these two aspects of light.
Now that we have some idea of what we are doing, let's plug in the numbers. The wavelength given is 3.5 μm, which is 3.5 x 10^-6 m. So,
E = (6.626 x 10^-34 J s) x (3 x 10^8 m/s) / (3.5 x 10^-6 m)
E = 5.686 x 10^-19 J
That's the answer! The energy of a photon of wavelength 3.5 μm is 5.686 x 10^-19 J. I hope that makes sense. If not, don't worry, you are not alone. This stuff is hard to grasp!