# Calculating neutrino flux density

1. Jun 27, 2004

### carvell

Third and final A2 Physics paper tomorrow.

Currently struggling with one of the articles we have been given to study before the exam. It's all about neutrinos. I've been given some questions to try, educated guesses by teachers on what could come up on the exam paper.

"If the Sun is 150 Gm away and produces 2 * 10^38 (2E38) neutrinos per second, what is the neutrino flux density at the earth's surface?"

My best guess based on what I know about magnetic flux density so far is:

2E38 / 150G = 1.3E27

I realise that 150Gm isn't an area, but that's the best I could do!

Is there anyone that can confirm my answer/tell me it's all completly wrong?

Thanks.

2. Jun 28, 2004

### Norman

Couple of things I can see wrong:
1) Units... your units are 1/(m*s)... this is wrong for flux
2) What does magnetic flux density have to do with this?

Try thinking about it this way: what size does the earth look like from the sun? Can you find the solid angle subtended by the earth at a radius of 150 Gm? Are you to assume that the particles are uniformally distributed