SnellsVerification

to determine the refractive index of a substance

or to Verify Snells Law

Title Verification of Snell’s law of refraction.

Apparatus

Glass / persex block, pins, a light box (laser) styrofoam.

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

Alternative Method To determine the refractive index of a transparent material

Draw the outline of the block on the page.

Line up 2 pins as so they make a line to the block, which makes an angle to the block.

Look through the block

place a pin so it blocks out the image of the 2 pins through the glass block

place another pin in so it blocks the line of the 3 pins when looking through the glass block

Draw lines that join the dot to the glass block

then under the block join the two points, where the drawn lines meet the outline of the block, to each other.

refractive index = Sin i/Sin r = n

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

How to use the graph to find a value.

Conclusions

Comments

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

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

https://sites.google.com/site/giantscience/maths-1/graphs

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

Comments