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

Aim: To investigate the factors affecting the e.m.f. induced in a coil due to a varying magnetic field in a neighboring coil.

Extracts from this document...

Introduction

Physics Formal Lab Report

Name: Yip Ka Man

Class: 6B

Class number: 31

Date: 16th April, 2008

Experiment number: C17

Aim:

To investigate the factors affecting the e.m.f. induced in a coil due to a varying magnetic field in a neighboring coil.

Apparatus:

1 CRO (dual trace)                                                      

1 Signal generator                                                      

1 Search coil (axial type)                                                

2 Square solenoids (different sizes)                                        

1 d.c. power supply                                                      

1 Light-beam galvanometer

1 a.c. ammeter

1d.c. ammeter

1 Rheostat

2 PVC-covered copper wire 26 s.w.g. (2 m long)

1 Magnetic field board

1 Stop watch

Connecting leads

Theory:

The electromagnetic induction is a phenomenon that a varying magnetic flux can induce an electromotive force (e.m.f.) in a coil. The induced e.m.f. depending on several factors can be described by the Faraday’s Law of Electromagnetic Induction:

Induced e.m.f. (ε) = -dΦ/dt

Where Φ is the magnetic flux enclosed by a one-turn-coil. Note that the negative sign denotes that the induced e.m.f. and induced current oppose the original change of magnetic flux.

If the magnetic flux linked with a coil of area A, having N turns and at right angles to the magnetic field of flux density B, the total magnetic flux (Φ) is NBA. Hence,

Induced e.m.f. (ε) = -NAdB/dt

Procedures:

A. Rate of change of magnetic flux

...read more.

Middle

  1. A graph of the induced e.m.f. (ε) against the number of turns (N) was plotted.

B. Number of turns of coil

  1. Steps 3 to 4 were repeated with the other values of numbers of turns of the copper coil around the solenoid. The results were tabulated.

No. of turns(N)

5

7

9

11

13

15

Induced e.m.f.(ε)/mV

0.04

0.05

0.06

0.07

0.08

0.09

  1. A graph of the induced e.m.f. against the number of turns was plotted.

C. Cross-sectional area of coil

  1. Two square solenoids of different cross-sectional areas were connected in series to the signal generator. The solenoids both had the same number of turns per unit length but one had a larger cross-sectional area than the other.
  2. 10 turns of the copper wire were wired tightly around the middle of each solenoid. One copper wire was connected to channel 1 of a dual trace CRO and the other to channel 2. The solenoids were kept well apart from each other.
  3. The signal generator was turned on and set to 1 kHz. The CRO setting was adjusted to display both whole traces on its screen.
  4. The time base of the CRO was switched off. The length of the vertical trace shown on the CRO was recorded, which represented the induced peak-to-peak e.m.f. in the copper coil for each solenoid.

Solenoid

Large

Small

Induced e.m.f.(ε)/mV

130

80

...read more.

Conclusion

From the results in steps 23 and 25 in Part E, it can be concluded that the induced e.m.f. is directly proportional to the rate of change of magnetic flux, i.e. a steady induced e.m.f. will result in a steady rate of change of magnetic flux.The solenoids are placed perpendicular to each other because this ensures that the magnetic field produced in each of the solenoids is not affected by that in the neighboring solenoids.Sources of error:

-There is reaction time of an individual.

-A stopwatch which is fast.

-The surrounding magnetic field of the neighboring solenoids may affect the experimental result.

-The setting and calibration of the CRO is wrong.

Suggested improvements:

-Repeat the experiment several times and take the average data for calculation.

-The time measured by a stopwatch is checked using another watch.

-Place the neighboring solenoids perpendicular to each other.

-Reset the setting and calibration of the CRO.

Conclusion:

From the experiment, it is observed that the factors affecting the e.m.f. induced in a coil due to a varying magnetic field in a neighboring coil are the rate of change of magnetic flux, the number of turns of coil and the cross-sectional area of coil.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics 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 Electrical & Thermal Physics essays

  1. Objective: To use a search coil and a CRO to investigate the magnetic ...

    is induced across the ends of the coil. The induced e.m.f. (?) is directly proportional to the rate of magnetic field, i.e. ? = -NA dB/dt .When the search coil is connected to a CRO, the corresponding induced e.m.f. and hence magnetic field magnitude can be determined. Precautions for magnetic field around straight wire 1.

  2. Investigating the E.m.f and Internal Resistance of 2 cells on different circuit Structures.

    For a parallel circuit, I also expected the internal resistance to be half of the internal resistance of a series circuit with two cells, due to the circuit formula for total resistance: 1/RT = (1/R + 1/r) + (1/R + 1/r)

  1. resistivity if a nichrome wire

    the power pack was turned off, the temperature of the wire may have not reached the initial temperature (room temperature) and would therefore the electrons would have had more kinetic energy and this will vary the resistance. In future, I was to carry this investigation again I would wait for

  2. The varying of the resistance of nichrome wire depending on its length

    Resistance is caused when they collide with atoms. Therefore, when the temperature is increased the collisions will also increasing, thus increasing the resistance. Resistors (sometimes made of a length of nichrome wire) can be used to reduce the current in a circuit. One use for a resistor is when the current flowing needs to be controlled, e.g.

  1. Investigating the factors affecting the size of current flowing through a length of resistivity ...

    If the cross sectional area of the putty is doubled by wiring two of the lengths in parallel, it has the same effect as wiring two of the ohmic resistors in parallel. The resistance is halved and so the amount of current flowing through the putty is doubled.

  2. The potato - a source of EMF

    From the data I have been given I can now calculate the internal resistance and the EMF of the potato cell. I will then compare the results from the three different distances between the electrodes and draw conclusions. I predict that the internal resistance will decrease as the electrodes are moved closer.

  1. Using an LDR to detect the intensity of plane polarised light allowed through a ...

    * Or, I could get a formula of the internet, and then use my data to comment on the effectiveness of my sensor. I have chosen to do the latter. As such, on http://lsn.curtin.edu.au/tlf/tlf1997/swan.html (a website intended to suggest to university lecturers how to include the subject of polarisation), I

  2. The electrolysis of copper from copper sulphate solution

    Average Current (Amps) (2dp) 1 0.53 0.8 0.31 0.6 0.23 0.4 0.14 0.2 0.09 0 0 Now I need to work out how many moles of electrons there are in coulombs for each concentration. Time MULTIPLIED BY Current Quantity of Electrons Quantity of Electricity DIVIDED BY 96000 Moles of electrons

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