# Homework Help: Path of Light Through a Circular Raindrop

1. Feb 25, 2010

### Tasha9000

Path of Light Through a Circular (Spherical) Raindrop

1. The problem statement, all variables and given/known data

I need to draw an accurate diagram of a light ray's path through a circular raindrop.
-The angle of incidence is 25degrees.
-n of water is ~1.33
-n of air is ~1.000293

I can calculate the first angle of refraction, but I cannot calculate the angle at which the light ray reflects from the raindrop. It does not say how in my textbook . Where is the normal?

2. Relevant equations

Snell's Law
nAsinA=nBsinB

3. The attempt at a solution

https://www.physicsforums.com/attachment.php?attachmentid=23940&d=1267138827g

angle of refraction:

B=sin-1((1.000293sin(25degrees))/1.33)=18.533

Last edited: Feb 25, 2010
2. Feb 25, 2010

### Tasha9000

3. Feb 25, 2010

### Tasha9000

Is this right or completely wrong?
https://www.physicsforums.com/attachment.php?attachmentid=23944&d=1267153824
(except with the arrows pointing the correct way)

4. Feb 25, 2010

### ideasrule

This is a sphere, so the normal at any point is the line that passes through the point, through the center, and straight to the other side.

5. Feb 25, 2010

### Tasha9000

Thanks!
I'm going to guess this is the correct answer:

#### Attached Files:

• ###### raindrop5.png
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6. Feb 26, 2010

### Redbelly98

Staff Emeritus
Looks right to me. Do they want you to calculate any of the distances in the figure, or is just getting the angles good enough?