Experiment 10: Faraday’s Law of Electromagnetic Induction Theory Faraday's Law of electromagnetic induction tells us that changing magnetic flux ΦB  through the surface bounded by the closed circuit induces emf E  in this circuit

Experiment 10: Faraday’s Law of Electromagnetic Induction

Theory

Faraday's Law of electromagnetic induction tells us that changing magnetic flux ΦB

 through the surface bounded by the closed circuit induces emf E

 in this circuit . Mathematically, this law states:

E= ?ΦB?t

(1)

where magnetic flux is defined as

ΦB=BAcos?

(2)

In Eq. (2), B

 is the magnetic field, A

 is the area of the surface magnetic flux passes through, and ?

 is an angle between direction of magnetic field and the normal line to the surface:

In this lab, we’ll check Eqs. (1) and (2) experimentally.

Procedure

Physics Simulations: Faraday's Law

https://www.geogebra.org/m/WjtWQbgC

Experiment

Part A.   Changing Magnetic Field

1. Choose variable “Variation of the magnetic field”.
2. Set the range of changing magnetic field B

   

    from +5T to -5T and measure the induced emf E

   

   . Record the result in the data table.
3. Repeat your measurements of E

   

    as you decrease the magnetic field range by 0.5 Tesla and record your data in the data table
4. Calculate E

   

    using Eqs. (1) and (2) and record your theoretical results in the data table.

Note: the radius of the circular wire loop in part A is 3m; time of experiment is 5s.

Range of B	5 T	4.5 T	4 T	3.5 T	3 T	3.5 T
E , exp.
E , theor.

Part B.   Changing the area of the wire loop

1. Choose variable “Radius of the loop”.
2. Set the radius of the circular wire loop to be 5m and measure the induced emf E

   

   . Record the result in the data table.
3. Repeat your measurements of E

   

    as you decrease the radius by 0.5 meters and record your data in the data table
4. Calculate E

   

    using Eqs. (1) and (2) and record your theoretical results in the data table.

Note: magnetic field in part B changes from +5T to -5T; time of experiment is 5s.

Radius	5 m	4.5 m	4 m	3.5 m	3 m	3.5 m
E , exp.
E , theor.

Part C.   Changing the angle θ

 between the field and the surface

1. Choose variable “Angle between the field line and the surface”.
2. Set the angle θ

   

    between the field and the surface somewhere in the interval between 5°

   

    and 10°

   

   and measure the induced emf E

   

   . Record the results in the data table. 
3. Repeat your measurements as you increase the angle θ

   

    by setting it in the intervals shown in the data table and record your data in the table.
4. Calculate E

   

    using Eqs. (1) and (2) and record your theoretical results in the data table.

Note: magnetic field in part C changes from +5T to -5T; time of experiment is 5s; the radius of the circular loop is 3m. Be careful: angle ?

 in Eq. (2) is equal to: ?=90°-θ

 !!

Interval	5°-10°	15°-25°	25°-35°	45°-55°	65°-75°
θ
E , exp.
E , theor.

Questions

1. In part A experiment, what was the range of change of the magnetic flux ΦB

   

    when magnetic field was changing from +5T to -5T? Give the quantitative answer with proper units.

2. In part B experiment, the magnetic field was changing with the same rate: from +5T to -5T in 5s, regardless of the value of the loop radius. Why was the emf changing when you used different values of the loop radius?

3. In part C experiment, was the magnetic flux ΦB

   

    increasing, decreasing or staying the same when angle θ

   

    was increasing? Explain your answer.