STPM Experiment 9 Electromagnetic Induction

STPM Experiment 9 Electromagnetic Induction (Second Term) Title: Induced e.m.f. Results: Part I:

Type of  Number of  solenoid, C turns, N C1 10 C2 20 C3 30 C4 40 C5 50 Centroid (30, 0.007)

Induced e.m.f., ε/V

1 0.001 0.004 0.007 0.010 0.013

2 0.001 0.004 0.007 0.010 0.013

Mean 0.001 0.004 0.007 0.010 0.013

Part II:

No.

Length of the solenoid, l  /cm

Diameter of the coil C3, D/cm

1 2 3 4 5 Average

19.00 19.00 19.00 19.00 19.00 19.00

4.54 4.54 4.54 4.54 4.54 4.54

Frequency of the a.c. signal, f  signal,  f  /Hz 1000 1200 1400 1600 1800 2000 2200 2400 Centroid (1700, 0.0075)

Root mean square current across the solenoid, Ir.m.s. /mA 10.00 10.00 10.00 10.00 10.00 10.00

Induced e.m.f., ε/V

1 0.004 0.005 0.006 0.007 0.008 0.009 0.010 0.011

2 0.004 0.005 0.006 0.007 0.008 0.009 0.010 0.011

Mean 0.004 0.005 0.006 0.007 0.008 0.009 0.010 0.011

Calculation: Part II:

              

 

            

     

                

  

                   



 



 

    

            



 



                                  

Discussions: (a) Precautions (i) The rheostat itself is also a solenoid and should be placed away from the other apparatus. (ii) All connections of wire and other devices must be in good contact. (iii) Carry out the experiment reasonably fast to prevent wires from heating up. (iv) The current is kept constant throughout the experiment. (b) Sources of error (i) Inaccurate diameter D of the coil C 3 obtained due the layer of plastic within the coil. (ii) End error of the meter rule used due to wear and tear. (iii) Instrument drift of the signal generator. (iv) Nearby magnetic source and magnetic fields may have slightly interfered with the experimental since magnetism affects all matter. (v) Difficulty to keep the current constant as we have fluctuating reading on the multimeter. (c) Steps to overcome the weakness of the experiment (i) Use a new metre rule.

(ii) (iii)

Take into account the thin layer of plastic within the coil when measuring the diameter of the coil C 3. Repeat the experiment for a several times to reduce random error and increase the accuracy of the results.

Conclusion: The induced e.m.f. increases linearly with the number of turns of the coil. -6

-1

The estimated value of permeability of free space,  µ 0 is 1.04x10 H m .