Experiment 12 Waves motion

Experiment 12 

Topic: Waves motion 

Title: Standing waves

Objectives: To determine the mass per unit length of a thread 

Theory:

The frequency of a standing wave in a stretched thread is given by

   

where f  is the frequency, T the tension in the thread, µ the mass per unit length and L the distance between two successive nodes.

Apparatus:

1. A G clamp 
2. An a.c. power supply (2 - 12 V, 50 Hz) 
3. A ticker timer
4. A pulley 
5. Thread    
6. A wedge  
7. A light pan 
8. Masses 1, 2, 5, 10, and 20 g 
9. A metre rule 
10. A triple beam balance

Procedure

(a)The apparatus is set up as in Figure below.

(b) Tie one end of the thread to the vibrator of the ticker timer and the other end to the light pan.

(c) The length of the thread from the vibrator to the pulley should not be less than 1.5 m.

(d) Add 10 g to the light pan and record the total mass M.

(e) Switch on the power supply.

(f) Place the wedge below the thread near to the pulley. Adjust the position of the wedge so that a steady stationary wave is observed.

(g) Measure and record the distance between two successive nodes.

(h) Add extra masses in increment of 1 g until another standing wave is observed. Measure and record P and M.

(i) Repeat step (h) to obtain at least five sets of reading. Tabulate L and W (W = Mg).

(k) Plot a graph of W against L2.

(l) Determine the mass per unit length μ of the thread used.

Data

Graph