The double slits experiment was conducted to observe the interference of light waves, to explore how interference pattern would be affected by different colours, and to determine whether interference would change if the angle of slits was changed horizontally or vertically. Hypothesis:
Dark and light bands would be seen, and red light causes wider nodal spacing, while blue light causes shorter nodal spacing. Materials:
In this experiment, a lamp base assembly, a piece of blue filter, a piece of red filter, a slit plate, a laser pointer, a meter scale, and a 40 W lamp were used. Procedures:
1. A 40 W lamp was assembled in a lamp base assembly, and the assembly was settled on the edge of a desk top. 2. The lamp was turned on. And the filament of the lamp was seen, from a distance, by a person through the double slits on the slit plate. The shape of the interference was recorded. 3. A piece of red filter was placed in front of the lamp, and the lamp was seen, from a distance through the same double slits. The change of the interference pattern was recorded. 4. The filament of the lamp was seen by a student standing a certain distance away through the same double slits with a piece of blue filter placed in front of the lamp. The change of interference pattern was observed. 5. The slit plate was rotated vertically and horizontally, while other factors were kept constant. The change of interference pattern was observed. 6. The laser light conducted by the laser pen was directed through the double slits onto a piece of paper located 3m away. The interference pattern was observed through the slits. 7. The nodal spacing on that piece of paper was measured.
8. Step 6 and step 7 were repeated at a distance of 2m away. Observations:
1. The patterns of lamp light interference were dark and light bands, while the patterns of laser interference were dark and light spots. 2. After the red filter was placed in front...