Ivan Perez
Section B
4-18-2021
Faraday’s Law
The purpose of this lab is to observe Faraday’s Law of electromagnetic induction
by changing the magnetic flux through coils by changing the placement of a bar magnet.
In this lab the magnetic flux is the amount of magnetic field passing through a
closed surface and the equation is where B is the magnetic field and A is the area of the
closed surface
𝐼𝑏 = 𝐵𝐴
In this lab the angle of the magnetic field is changed so the equation above in terms of
angles can be written as
𝐼𝐵 = 𝐵𝐴𝑐𝑜𝑠θ
Since we are moving a magnet close to and far away from a closed surface, we use
Faraday’s law which is
−𝑑𝑒𝑙𝑡𝑎𝐼𝑏
= 𝑉𝑒𝑚𝑓
𝑑𝑒𝑙𝑡𝑎𝑡
Equipment:
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DC power supply
Galvanometer
Bar magnets
A decade rheostat
A resistive coil
Primary and secondary coils
Tap key
Metal cores
The procedure of this lab consists of first setting up the circuit correctly. Afterwards
first test and record the readings on the galvanometer when inserting each individual side
of the bar magnet into the coil. Then the next test will involve inserting a secondary coil
into the primary coil from each end and recording those readings. Then changing the
material of the end of the secondary coil with aluminum and iron and recording their
separate distinct readings. Finally, the secondary coil will be placed close above the
primary and the horizontal angle will be changed values recorded.
Data:
Observation 1
When the north side of the bar was inserted the galvanometer, reading went left also
when the bar was removed. When the south side of the bar was inserted, the reading went
right but when it was removed the reading went left.
Observation 2
When inserted from the northside the galvanometer reading went left and when inserted
from the southside the reading went right.
Observation 3
When the end was covered with aluminum the reading of the galvanometer was
amplified, the readings form the last observation, and when the end was covered in iron
the amplification was greater because iron is more susceptible than aluminum.
Observation 4
When the angle of the device was altered the galvanometer reading intensity decreased as
it became perpendicular to the coil then increased to the opposite reading.
Angle
Deflection Amount
0
45
90
135
180
150mA
75 mA
0
75 mA
150 mA
Deflection
Direction
Right
Right
Left
Left
Secondary Current
150
39.400
0
-74.707
-89.769
Results:
The galvanometer showed a positive reading when the current’s direction was
inline with the direction of the circuit and read negative when it went the opposite
direction. The speed at which the magnet moved determined the intensity of the reading
of the galvanometer. The pole of the magnet was relevant to what was shown on the
galvanometer as equal to the coil the magnet has a magnetic field. It was the iron that was
ferromagnetic since it is easily magnetized because of the positioning of its magnetic
moments. A source of error that may have occurred would be the readings during the
experiment. As a result of the setup the galvanometer could only read impulses in order
to no overload the circuit which may have caused incorrect readings. Preventing having
to do impulses is a way which the experiment can be improved.