# 3B Scientific Demonstration Monochord User Manual

## Instruction sheet

3

Instruction sheet

3B SCIENTIFIC® PHYSICS

U15100 Monochord

4/03 ALF

®

The Monochord demonstrates how the pitch of the
sound produced by vibrating strings is dependent on
their tension, length and thickness.

1. Description, technical data

The monochord consists of a wooden sound box over
which two steel strings and a nylon string are stretched.
The tension of two of the strings can be adjusted by
means of tuning pegs at one end while the third is
adjusted by running it over a pulley and attaching weights
or a dynamometer. The effective length of the strings

can be adjusted using two moveable bridges. The lengths
can be read from a scale on the side of the box.

Dimensions of sound box: 700 mm x 90 mm x 70 mm
Scale length:

600 mm

Scale divisions:

cm and dm

2. Instructions for use

• Excite the strings by plucking them or bowing them.

• The desired length of the strings can be set by mov-

ing the bridges and can be read from the scale.

Name of

Frequency

Interval

Ratio of string

note

ratioroot : overtone

lengthsroot : overtone

c : c

1:1

root

1:1

c : d

8:9

second

9:8

c : e

4:5

major third

5:4

c : f

3:4

fourth

4:3

c : g

2:3

fifth

3:2

c : a

3:5

major sixth

5:3

c : h

8:15

major seventh

15:8

c : c`

1:2

octave

2:1

c : g`

1:3

3:1

c : c``

1:4

4:1

c : e``

1:5

5:1

c : g``

1:6

6:1

A major scale can be generated by adjusted the length of the strings to the following ratios:

1

Tuning peg

2

Pulley

3

4

Sound box

5

Scale

1

2

3

4

3

5