# Finding n

Title Verification of Snellâ€™s law of refraction.

Apparatus

Method

1. Place transparent rectangular object on a sheet of paper
2. Trace the outline of the block on the sheet
3. Remove the block,
4. 1/3 down the outline mark a tick on the page
5. Using a protractor mark out the following angles 10, 20, 30o, 45o, 60o, 75o, these are your angles of incidence
6. Complete lines to show the angles.
7. Set up the ray box as so a ray shines along one of these lines.
8. on the other side of the block make a mark where the refracted ray leaves the block, beside this mark note the angle of incidence
9. repeat steps 7 & 8 until all the corresponding refractions positions have been found
10. remove the block complete the lines from the point the light entered to where it left, this is the direction of the refracted ray
11. measure the angle from the normal to the refracted ray.
12. Place all the data in a table of the angles of incidence and of refraction

Diagram

Safety Concerns

Results / Observations

What did you see or notice

Maths

1. Plot sin i Vs sin r
2. Finding the slope of the graph = sin i / sin r = n = refractive index

Conclusions

Appropriate calculations.

1. glass block 6.5cm across, how far below the incident ray normal does the light come out of the block if the initial ray was at an angle of 17o

3. Measurement of the refractive index of a liquid or a solid.

Title Measuring the refractive index of a liquid.

Apparatus

Method

1. Set up the retort stand with a cork and a pin
2. At the bottom of a beaker (lrg gas jar) place a pin,
3. Fill this beaker with water to the very brim
4. Place a small regular mirror on the beaker so the back of the mirror is level with the water surface.

Safety Concerns

Results / Observations

What did you see or notice

Maths

1. Plot Real Depth Vs Apparent Depth
2. Finding the slope of the graph = n = refractive index

Conclusions