Ei-2 Lecher Wires

Aim

To demonstrate standing electromagnetic waves on a transmission line consisting of a pair of parallel wires.

Apparatus

  • Metre wavelength transmitter
  • Lecher wires
  • Attachments containing globes, shorting bars, etc

Lecher Wires

Lecher Wires Setup.

Description

The output of the transmitter is connected to the co-axial input of the lecher wire apparatus. If the globe is moved along the wires the intensity will cycle through minimum and maximum intensity corresponding to the nodes and antinodes of the standing wave. The distance between nodes corresponds to a half wavelength.

The globe may be positioned at a node and if the end of the Lecher wires is shorted the globe will then indicate an antinode.

In the open circuit case the end must be an antinode (E field max).

In the short circuit case the end must be a node (E field zero).

Videos