• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Investigate the factors affecting the induced e.m.f. in a coil due to the changing magnetic field in a neighbouring coil.

Extracts from this document...

Introduction

Physics Practical Report                

The Law of Electromagnetic Induction

Objective:        To investigate the factors affecting the induced e.m.f. in a coil due to the changing magnetic field in a neighbouring coil.

Apparatus:        Two square solenoids with different sizes, a CRO, a signal generator, an ammeter (1A a.c.), two PVC covered copper wires with different lengths, a magnetic field board, an axial search coil, connecting leads, a connecting plug.

THEORIES

Faraday’s law states that the induced e.m.f. is directly proportional to the rate of change of flux-linkage or rate of flux cutting, i.e.

image00.png

where image01.png is the induced e.m.f. in a coil of N turns through which a magnetic flux image12.png is passing.

The proportional constant is found to be 1. Therefore, we have

image21.png

The magnetic flux image12.png is defined as the product of the flux density normal to the surface and the area of the surface, i.e.

image22.png

image23.png

Therefore, the induced e.m.f. is found to be

image24.pngimage25.png

Hence, the factors affecting the induced e.m.f. in a coil due to the changing magnetic field in a neighbouring coil are rate of change of magnetic field (frequency of A.C. supply,f), magnetic field strength (current through the solenoid, B), number of turns of coil N, the area of surface of solenoid A

...read more.

Middle

At the beginning of the experiment, the frequency of signal generator is set at 500Hz. The current is set at 860mA. The smaller square solenoid is used. l is the peak-to-peak reading in C.R.O.

The frequency is changed to investigate its effect on induced e.m.f. The current is kept constant every time whenever the frequency is changed.

Investigation 1:        Rate of Change

Results:

f / Hz

500

600

700

800

900

100

l / cm

3.0

3.4

4.0

4.4

4.6

4.9

The graph of l against f is drawn on a separate graph paper (GRAPH 1).

Measurements:

From the graph, it can be said that the relation between l and f is linear. Although several points are quite far from the lines, three of the points can be connected firmly in a straight line.

Then the frequency is reset to 500Hz. The smaller square solenoid is used.

The current supply is changed this time to investigate its effect on induced e.m.f.


Investigation 2:        Field

Results:

I / mA

100

200

400

600

800

1000

l / cm

0.4

0.8

1.5

2.2

2.8

3.6

The graph of l against I is drawn on a separate graph paper.

Measurements:

From the graph, it is easily observed that the relation between l and I is linear as the points nearly lie in a straight line (GRAPH 2).

Then the frequency is kept at 500Hz. The smaller square solenoid is used. The current is also kept constant at 860mA.

...read more.

Conclusion

Sources of errors

1.        The frequency of A.C. generated by the signal generator might not be correct. When the experiment was carried out, it was found that 10 x 100Hz was very different from 1 x 1kHz as seen on the C.R.O. screen where the latter one had a high level of inaccuracy. It had been assumed that the frequency indicated on the signal generator was correct. However, this might not be a significant source of error in finding out just the relationship between induced e.m.f. and frequency since the induced e.m.f. could still increase with increasing frequency.

2.        The ends of the wires around the solenoid could induce e.m.f. However, this seems not to be a significant source of error because the effect is quite small unless the ends of the wires are put around the solenoid.

3.        The axial search coil should be put in the centre of the 10-turn coil. Otherwise, the result obtain would not be the maximum value which may affect the angle through which the axis of the search coil.

Possible Improvements

  1. Measure the frequency generated by the signal generator each time when the effect of varying frequency on induced e.m.f. is observed to ensure the signal generator gives out desired frequency.
  2. Place the search coil as near in the centre of the 10-turn coil as possible to reduce the error.

Page

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Fields & Forces section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Fields & Forces essays

  1. Using a search coil and CRO to investigate the magnetic fields generated by alternating ...

    Random Error CRO The CRO is used for the measurement of the potential difference across the capacitor. The smallest division is 0.1V. Maximum possible error is �0.05V Maximum percentage error of the measurement: � 100% = 5% Ammeter The ammeter is used for the measurement of the current passes through the capacitor.

  2. Objective of Experiment. To use a search coil and CRO to investigate ...

    The result was then tabulated. Results Signal generator frequency f = 5000Hz Length of vertical trace on CRO l/cm 0.80 1.40 2.10 2.80 3.40 Current I/A 0.1 0.2 0.3 0.4 0.5 4.00 4.60 5.20 5.55 6.40 0.6 0.7 0.8

  1. What Affects the Strength of Magnetism Exerted By an Electromagnet?

    Lines of flux are never directly transferred from piece of metal to another. In this case, the lines of flux induce magnetism into the nearest paperclips. These paperclips will then induce some of their magnetism into other nearby paperclips. Taking the above diagram and theory into consideration, the transferred magnetism

  2. Measuring The Constant g; The Acceleration Due To Gravity

    - 1.2 9.8286 Conclusions To Data To conclude, the above results show to the high degree of accuracy and precision I calculated 'g', the second method proving even more effective than the first. My final calculated value for 'g' is 9.81, to 2 significant figures.

  1. Investigating a factor affecting the voltage output of a transformer.

    20V* 1/2=10V If we half V1, V2 should also half; when V1=10, V2 should =10 (when N1 and N2 are equal) 10V*1=10V when V1=10, V2 should=20 (when N2 is double N1 [step-up transformer]) 10V* 2/1=20V when V1=10, V2 should=5 (when N2 is half N1 [step-down transformer])

  2. To investigate the effect of current on the strength of an electromagnet field.

    of the magnet and so its permeability as ferromagnetic materials such as iron have large magnetic pereambility. This will be kept constant by using the same wire coiled around the magnet throughout the experiment. 3. Length of Soft Iron The longer the soft iron bar , the more domains there

  1. Investigation of determination of flux density of magnets(plane)

    By adding small weights to the other side of the frame, I can finally make the balance go the equilibrium. There fore the magnetic force is equal the restoring weight. In this case, I will use some little pieces of paper as they are small and light enough to get an quite accurate mass value.

  2. To see how the number of coils on an electromagnet affect its strength.

    Apparatus: The apparatus that we used were: o 4 Volt Power pack o Crocodile Clips o Wires o Solenoids o Iron nail o And paper clips Diagram: Plan: My plan is to see what effect the number of coils has on the strength of an electromagnet.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work