Question

1. How does the Stephan-Boltzmann law show that for the same size star, blue-white star is very bright while a red star is barely visible at all?

2. Why doesn't a hydrogen atom absorb all wavelengths of light that hit it?

3. How does the Bohr model of the atom explain Kirchhoff's Laws?

4. Assume a water molecule is 3x10^-26 kg. You pour a small glass of water which is about .3 kg and drink it. How many molecules of water did you drink?

5. Let's say you take a laser that shines at a wavelength of 656.6 nanometers. Now, someone attaches it to a rocket and fires it away from your with a recession speed of 0.9 times the speed of light. What wavelength do you see it to be?

Answer 1

1.

The methamatical relationship between energy radiated per second and temperature is given by  Stefan- Boltzmann law

L = AT⁴

Where , L = Energy radiated per socond

   = stefan-boltzmann constant

A = surface area

T = absolute temperature (K)

According to the Wein's law : _max = (2.90×10^-3)/T

L is the energy radiated per second or Luminosity, this tells us how many times brither than the sun , the star will appear.

From the Stefan's law , we come to know that

L T⁴

and from Wein's law , T 1/

Or L 1/⁴

Wavelength of Red color is higher than that of Blue- white , hence its luminosity would be least.