Investigating total internal reflection Method 1. Place your Perspex block in the middle of a piece of A4 paper and draw round it. 2. Draw the normal line at right angles to the bottom of the block 3. Shine the light from a ray box onto the block so that the angle of incidence is 10 4. Draw the emerging ray 5. Measure the angle of refraction and record it in the table 6. Repeat this for 15, 20,25, 30, 35., 40 and 45 angle refraction A4 SHEET OF PAPER emerging O ray angle Incidence perspex block rav A norm M Angle of incidence () Angle of refraction () 10 15 20