Sonometer Experiment

Aspect 1

Research Question/ Problem:

Study of resonance length with the tension applied on the Sonometer wire made by steel when the frequency of the given tunning fork is taken constant.

Selection of variables

Responding Variables: Resonance length between the bridges –

With the change in the applied tension on the wire, the length b/w the bridges will change.

Manipulated Variable: Tension applied on the wire –

By changing the mass applied at hanger tension on the wire can be changed independently.

Controlled Variables:

1). Material of the wire

2). Cross-section area of the wire is taken as controlled variable because these may affect the balancing length.

3). Temperature because it may affect the dimensions of the wire.

Hypothesis:

As per the law of length, in case of fundamental mode of vibration the length of the wire between the bridges (L) is proportional to √T. If controlled variables are taken constant.

Thus, graph b/w l2 and tension (T) must be straight line.

Method to control Variables

Manipulated Variables: The tension in the wire, it can be changed by using slotted weights on hanger.

Responding Variables: In case of fundamental mode of vibration the resonance length b/w the bridges will vary with the applied tension. To measure this length bridges must be sharp and they must be positioned properly on the Sonometer.

Length b/w the bridges must be measured by using a meter scale with zero instrumental error.

1). Avoid airflow near the exp. Setup because the rider (on the wire) may fly off.

2). Place the tuning fork gently on the Sonometer.

3). Hold the tuning fork from stem.

4). Sonometer must be placed upon a shock-absorber platform to avoid surrounding vibrations.

5). The wire must be straight without any kink.

Risks:

1). The fork should be placed gently, so that the person who is performing the experiment doesn’t get hurt.

2). The weights should not be placed beyond a limit because if this is done then the apparatus may topple down or the wire may break.

3). Make sure that your foot is not below the hanger. If the hanger falls it may hurt the person and cause injury.

Experimental Design Aspect 3

Apparatus Used:

Device Name Specifications QuantityRubber Pad - X1Electronic Weighing Machine

Max. Weighing capability 10Kg.

X1

Tuning Fork 512HZ X 1Metal Wire Made by Steel X1Sonometer Having Length 1m X1Hanger Of mass ½ kg. X1Wooden Wedge With Sharp Edges X2½ Kilogram Slotted Weights

- X7

Procedure

1. Place the Sonometer on a stable surface such as a table.2. Test the pulley and make it frictionless through oil (if necessary).3. Put suitable maximum weight in the hanger.4. Move one of the wooden bridges outward to ensure maximum length of

the wire between the two.5. Take a tuning fork of least frequency from among the set. Strike its prong

with a rubber pad to make it vibrate.6. Pluck the wire from the middle and leave it to vibrate.7. Listen sound produced by tuning fork and wire and judge, which has less

frequency.8. Since the long wire may have less frequency, decrease its length by

moving the bridge inwardly. Check frequencies again.9. Go on decreasing the length till frequency of vibrating wire becomes

equal to the frequency of the tuning fork.10. Put an inverted V shape light-weighted rider on the wire, at its middle

point. Vibrate the tuning fork and touch the lower end of its handle with sonometer board. The wire will vibrate due to resonance and the rider will fall.

11. Note the length of the wire between the edges of the two bridges and record it in ‘length decreasing’ column.

12. Bring the two bridges closer and then adjust the length of the wire by increasing gradually. Keep increasing the length till the rider falls.

13. Note the length of the wire and record it in ‘length increasing’ column.14. Repeat steps 1 to 13 with a tuning fork of frequency 256Hz and load of

4kg.15. Remove slotted weights one by one to reduce load to 3.5kg, 3kg, ……. , 1kg

and repeat above steps with the same tuning fork.16. Record observations as given below.

Increasing Table:

S. No. Mass of the Hanger (g) (+/- 0.5) (A)

Mass of the slotted weight (g) applied (+/- 0.5) (B)

Position of 1st wedge (+/- 0.1 cm) (L1)

Position of 2nd wedge (+/- 0.1 cm) (L2)

0

1 445 0 40

2 445 3205 40.5 63.4

3 445 2760 40.5 62.3

4 445 2310 40.5 60.6

5 445 1845 40.5 59.5

6 445 1385 40.5 57.5

7 445 915 40.5 55.3

Decreasing Table:

S. No. Mass of the Hanger (g) (+/- 0.5)

Mass of the slotted weight (g) applied (+/- 0.5)

Position of 1st wedge (+/- 0.1 cm)

Position of 2nd wedge (+/- 0.1 cm)

01 445 0 402 445 915 40.5 553 445 1385 40.5 57.74 445 1845 40.5 59.45 445 2310 40.5 60.86 445 2760 40.5 62.47 445 3205 40.5 63.38 445 3240 40.5 67.59 445 3725 40.5 68.6

Data Analysis