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

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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,

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Induced e.m.f. (ε) = -NAdB/dt

Procedures:

A. Rate of change of magnetic flux

  1. A square solenoid was connected to a signal generator through an a.c. ammeter.
  2. 10 turns of a copper wire were winded tightly around the middle of the solenoid and the wire was connected to a CRO.
  3. The signal generator was turned on and set to 1 kHz. The CRO setting was adjusted to display a whole trace 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 ...

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