Interference

  • OP3.1 Air Wedge

    A thin air wedge will separate the spectrum of white light. The thickness at one end is bigger than the other, thereby allowing different wavelengths to pass through at different thicknesses due to interference. This is seen on a screen.

  • OP3.2 Double Slit Diffraction

    This is a laser interfering with itself through two slits. The result on the screen will be clearer if the room lights are dimmed.

  • OP3.3 Michelson Interferometer

    This is a small table top version of the classic experiment using a neon laser or sodium lamp. There also is an acoustic interferometer in F11.

  • OP3.4 Microwave Interferometer

    Same as Michelson interferometer, but here we use microwaves (3cm) instead of a laser. The microwave apparatus that has a stationary and spinning arm is employed. The items in C23 will help--one of the gratings acts like a silvered mirror, while the sheet metal acts like a full mirror. Peaks in intensity can be noticed by moving the sheet metal mirror--the one that lies along the original path.

  • OP3.5 Soap Film

    A soap film is place inside a metal ring. The ring sits on a stand that allows the ring to rotate in a plane through and angle of 180°. Using the stage light to shine through the film and the lens in the shelf to focus the image on the screen, a soap bubble's interference can be seen--black on top and colorful on the bottom. The resulting image will be inverted.

  • OP3.6 Young's Experiment using Microwaves

    The apparatus consists of two microwave generators and one meter. The generators are placed a small distance away from each other, facing the same direction. The meter is carried by the instructor in front of the generators. The meter, big enough so that the class sees the needle move, shows peaks and zeros of the interfering waves. An AC hum can be used as an auditory indicator of intensity. The wavelength of the microwaves is 12cm. Instead of using the two sources, replace the clip in the generator by a paper clip that would act like a dipole, which would demonstrate the dipole pattern. This pattern will follow the sine squared law: zero directly above the dipole and maximum perpendicular to it.

  • OP3.7 Young's Experiment using Sound

    The idea is the same as above. The difference is that an oscillator puts out a sound two speakers and a microphone attached to an oscilloscope is used to detect the sound.