1. Jun 16, 2011

### namvip6666

1. The problem statement, all variables and given/known data
1. A light ray reflected from a flat mirror moves through an angle of 143* as the mirror is rotated. Through **what angle was the mirror rotated?

2. The speed of light in a material is 0,57c. what is the critical angle of a light ray at the interface between the material and a vacuum?

3.The electric field of plane electro magnetic wave is E=240V/m. At the same instant of time the magnetic field is....?

2. Jun 16, 2011

### tiny-tim

welcome to pf!

hi namvip6666! welcome to pf!

show us what you've tried, and where you're stuck, and then we'll know how to help!

3. Jun 16, 2011

### namvip6666

Re: welcome to pf!

Can you solve for me all of them. I don't kno*w how to do it.

4. Jun 16, 2011

### phinds

Re: welcome to pf!

That's not how this forum works. Read the forum rules and post the problem in the proper format, as tiny-tim said to. Once you've shown what you DO understand and what you DON'T understand, then we can help with what you don't understand.

5. Jun 16, 2011

### namvip6666

Re: welcome to pf!

So, can you tell me the formular to calculate it?

6. Jun 16, 2011

### phinds

Re: welcome to pf!

Read the forum rules and post the problem in the proper format as I said in the first place

7. Jun 16, 2011

### tiny-tim

no, namvip6666, if you're going to learn, you tell us the formulas

1 is about reflection of light, 2 is about refraction of light, 3 is about E and B of a plane wave …

tell us what equations you know about these three situations …

if you don't know any, go back to your lecture notes or your book, and find some
so study!

8. Jun 16, 2011

### Saitama

Re: Please!!! Help me.. I'm student.

Namvip6666, if you seek help here on the physics forums in your homework, you need to show some of your attempts at the solution. If you just come here and plead that "i am a student, please help", "Please give me the solution to it" no one is gonna help you. Moreover you should first check the rules before asking help in Homework section.