# 3B Scientific Kundts Tube User Manual

## 3b scientific, Physics

3B SCIENTIFIC

®

PHYSICS

1

Kundt's tube U8432845

Instruction sheet

05/11 ALF

1 Movable plunger
2 Kundt's tube
3 Cork powder
4 Stand (not included)
5 Refill rail

1. Safety instructions

Store the glass tube in a safe place where it
cannot be exposed to danger of shocks or
breaking.

Do not expose the glass tube to any mechani-
cal stress or strain.

Do not bend the movable piston while pushing
it in or pulling it out.

Do not use the apparatus, if the glass tube is
damaged.

Protect the apparatus from humidity and dust.

2. Description

By employing cork dust, a Kundt’s tube is used to
demonstrate the distribution of nodes and anti-
nodes in a standing sound wave. Using the appara-
tus, it is also possible to demonstrate that standing
waves are formed when a resonance condition is
fulfilled for sound wavelength

λ and length s of the

vibrating air column in the tube such that:
s = n

λ/2 for reflected waves with antinodes at the

open end,
s = (2n+1

)λ/4 for reflected waves with nodes

(n = 1, 2….n) at the closed end.

The wavelength can be determined from the num-
ber of nodes n and the distance a between the first

and last nodes
λ = 2a/(n − 1).
The rod with the cork plunger seals the tube and is
used for changing the effective tube length to tune
the frequency of the resonant sound waves.

A whistle, a tuning fork or a loudspeaker driven by
a function generator can be used as a sound
source.

A funnel reduces the wave impedance at the open-
ing of the tube. As a result, more sound energy can
be introduced into the tube.

2.1 Scope of delivery

1 Glass tube

1 Movable piston

1 Funnel

1 Whistle

1 Refill rail

3. Technical data

Tube:

600 mm

Internal diameter:

17 mm

Glass thickness:

1.5 mm

Movable plunger:

280 mm x 3 mm dia.