Physics Prac - Mesuring Wavelengths of Light

Aim: To determine the approximate value of l for red light using a diffraction kit.

Theory: Diffraction of light is one explanation of the wave theory of light. Francesco

Grimaldi first observed this type of behvaiour from light. However, Thomas Young was the

scientist that was able to derive a mathematical formula where l can be calculated. The

original experiment involved sending white light into a screen with two small holes to

serve as point sources. The light from these sources was then projected onto a screen and

light and dark bands were observed. The mathematical formula could then be used after

taking certain measurements.

Equipment: Light source (Ray box), Red cellophane, Double-slit slide, and Measuring rod

(can be already attached to Ray box.

Method:

1. Set up the ray box and place red cellophane in clip so that it is over the bulb.

2. Switch on ray box and stand approximately two meters away from the ray box, hold the

slide up to your eye and look through one of the double slit patterns into the light.

Observe disturbance pattern.

Aim: To determine the approximate value of l for red light using a diffraction kit.

Theory: Diffraction of light is one explanation of the wave theory of light. Francesco

Grimaldi first observed this type of behvaiour from light. However, Thomas Young was the

scientist that was able to derive a mathematical formula where l can be calculated. The

original experiment involved sending white light into a screen with two small holes to

serve as point sources. The light from these sources was then projected onto a screen and

light and dark bands were observed. The mathematical formula could then be used after

taking certain measurements.

Equipment: Light source (Ray box), Red cellophane, Double-slit slide, and Measuring rod

(can be already attached to Ray box.

Method:

1. Set up the ray box and place red cellophane in clip so that it is over the bulb.

2. Switch on ray box and stand approximately two meters away from the ray box, hold the

slide up to your eye and look through one of the double slit patterns into the light.

Observe disturbance pattern.