# Sonometer Experiment-Physics-Lab Mannual, Exercises for Physics. Allahabad University

## Physics

Description: This is lab manual for Physics course. It was designed by Sakash Jashith at Allahabad University. It includes: Frquency, Sonometer, Step-down, Transformer, Hanger, Weights, Wedges, Electromagnet, Vibrations, Transverse
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© Javaid Khurshid, PIEAS Page
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Experiment : M
ELDE
S
E
XPERIMENT
Object:
To determine frequency of A.C. mains using Sonometer.
Apparatus:
A sonometer with a steel wire.
Electromagnet
A step down transformer(220V to 6V or 12 V)
Hanger with slotted weights of 500g each
Meter Rod
Two wedges
Formula used:

Sonometer
Procedure:
i. To perform this experiment usually a sonometer is used in which an
electromagnet is fitted in the middle.
ii. Connect one end of a steel wire of uniform diameter to peg and
connect other end to hanger after passing it over two wedges and a
frictionless pulley.
iii. Put suitable slotted weights in hanger so that the wire may remain
in tension without any bends or kinks.
iv. Place one wedge on one side and the other wedge on other side of
electromagnet at nearly equal distances from centre. Also put a
small rider of paper on the wire above the electromagnet.
v. Switch on circuit of electromagnet.
vi. Adjust position of wedges by moving them slowly outward until
there is vibration in the wire.
vii. Adjust the wedges so that the amplitude of vibration is maximum
and transverse stationary waves could be seen with nodes at
wedges and anti-notes in the middle.
viii. Measure length of segment of wire between wedges by meter rod
twice by repeating step (iv) and find its mean value ‘l’.
ix. Repeat step (iii) to (viii) by changing weights in hanger at least five
times.
L
M
(resourcefulphysics.org)
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© Javaid Khurshid, PIEAS Page
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x. Take a piece of 100cm of same steel wire .Measure its mass by
physical or electronics balance and divide it by 100 to get mass of
wire per cm (m
o
)
xi. By putting values of l, m
o
, M and g in formula
xii. Calculate frequency ‘f’ of A.C. supply for each set of observation
and then find mean value of ‘f’.
Observation:
Mass of 100cm of wire = m = ---------------gm
Mass of per cm of wire = m
o
= m/100 = ----------------gm/cm
Acceleration due to gravity = g = = 980 cm/s
2
Calculations:
For observation 1 =

=
For observation 2 =

=
For observation 3 =

=
For observation 4 =

=
Mean Value of ‘f’ =
Results:
Frequency of A.C. mains, experimentally found is =
Actual frequency of A.C. mains =
Percentage of Error =
(Experimental Value – Actual Value)* 100 / Actual Value =
Sr.#
Mass Suspended with wire
including mass hanger M in
gm
Resonate length of segment
of wire between two wedges
1
cm
2
cm
Mean ‘l’
cm
1
2
3
4
5
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