Additional Info

• ID Code: K8-42
• Purpose: Demonstrates transmission of energy in electromagnetic waves. Shows the radiation pattern of the dipole antenna
• Description:
  This demonstration is centered on a simple radio transmitter with an antenna, which sends a signal to a handheld dipole antenna connected to a light bulb. The receiving antenna can be moved around in space, keeping the two antennas parallel, to observe the dipole radiation pattern. Rotating the receiving antenna to a vertical orientation shows that the radiowaves are polarized, as seen by the light going out.

  Background

  An antenna receives an induced current from the electromagnetic field of the passing wave. The dipole is a linearly polarized antenna, sensitive to signals oriented in a particular direction. In this experiment, we can see this dramatically, as changing the orientation of the antenna relative to the source produces a significant drop in signal strength, so that it is no longer receiving sufficient energy to light the bulb.

  Compare this effect to other wave and polarization demonstrations in sections G3 and M7.

• Availability: Available
• Loc codes: FS1