Describe how magnetic flux changes with relationship to flux = BA cos(theta)

Question 1

What is magnetic flux?

Answer 1

Magnetic flux is the amount of magnetic field that passes through a surface of area.

Question 2

How do we define an area vector?

Answer 2

We define the area vector that is perpendicular to the plane of the loop

Question 3

How else do we determine the area vector?

Answer 3

The component of the magnetic field that pierces the surface, not skims along it.

Question 4

What is the unit for flux?

Answer 4

Webers (Wb)

Question 5

Why does the formula HSC sheet show the magnetic field parallel?

Answer 5

component of the magnetic field parallel to the area vector (not parallel to the surface)

Question 6

Can flux be negative and positive?

Answer 6

Yes, it can be either positive and negative

Question 7

What is magnetic flux density?

Answer 7

B = flux/area

Question 8

Explain when the maximum voltage occurs what is the polarity of the terminals of P and Q.

Answer 8

The flux (into the page) threading the loop is decreasing, inducing an emf proportional to the rate of change of flux by Faraday;s law. By Lenz’s law, the induced current flows in such a direction such that the magnetic field due to the current opposes the change in flux induces the current. Hence the induced current flows clockwise, producing a magnetic field into the page. Hence the electrons move from P to Q, making the Q the negative terminal and P the positive terminal.

Question 9

Explain the polarity of the terminals but in simple terms.

Answer 9

1. Flux decreases into the page
2. Induces an Emf to rate of change by Fara’s law
3. As per Lenz’s law, the induced current flows the direction such that the magnetic field due to the current opposes the change in flux that induced the current.
4. Direction of the induced current
5. Magnetic field is produced as a result
6. Electrons move from P to Q (polarity of the terminals)