Physics II Experiment 1 Sample Report 2

Practical 1
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To investigate how the resonant frequency f of a vibrating wire is affected by the tension F of the wire

Objectives:
To study stationary waves in a string.
To find the mass per unit length of a string using standing waves in the string.

Apparatus and Materials:
1 Function generator
2 Thread
3 Pulley
4 Wooden wedge
5 Slotted masses
6 Meter rule
7 Vibration generator

Setup:

Figure 1-1

Theory:
Velocity of a wave:
If F = tension in the string µ = mass per unit length of the string v = velocity of the wave

Then,

If L = distance between two nodes along a standing wave
Then, for fundamental resonance frequency,

Let:
F = weight of the load; F = w = m g m = mass of the load

Then,

Procedure:
1 A 10 g slotted mass was hung from the thread and the function generator switched on with the frequency of the function generator set to 30 Hz. A wooden wedge was placed below the thread and next to the pulley.
2 The position of the wooden wedge was adjusted so that a steady stationary wave was observed. The shape of the stationary wave was drawn, and the node and antinode identified.
3 The distance between two successive nodes, L was measured and the total mass of the hanging load m recorded. The total weight w of the load was thus calculated.
4 The measurement was repeated by adding extra slotted masses so that eight (8) sets of readings of m and L were obtained.
5 The values of m, w, L, and L² were tabulated.
6 A graph of w against L² was plotted.
7 The gradient of the graph was calculated.
8 From the gradient of the graph, the mass per unit length, µ of the thread used was deduced.
9 The mass and length of the string was measured and the mass per unit length determined.
Data:

Frequency of function generator, f = 30.00 ± 0.01 Hz.
Mass of string, m = 0.48 ± 0.01 g
Total length of string, l = 1.548 ± 0.001 m

Mass of slotted masses, m (g)
Tension on string,

Bibliography: and references: if any.