Electric Fields and Electromagnetism

Question 1

What is an electric field?

Answer 1

A volume of space in which a charge experiences a force.

Question 2

Electric Field Strength

Answer 2

The electric force exerted per unit charge on a positive test charge placed at that point in the field.

Question 3

Electric Potential

Answer 3

The electric potential at a point is equal to the work done per unit charge in moving a positive test charge from infinity to that point in the electric field.

Question 4

Electric Potential Energy

Answer 4

The EPE at a point is equal to the work done in moving a positive test charge from infinity to that point in the electric field.

Question 5

Magnetic Flux Density

Answer 5

The force exerted per unit length on a long straight conductor carrying unit current and placed at right angles to the direction of the magnetic field at that point. (from F=BIL).
(Could also say the magnetic flux per unit area)

Question 6

Hall Voltage

Answer 6

The voltage produced across (the width of) a conductor when a current flows through the conductor at right angles to a magnetic field.

Question 7

Faraday’s Law

Answer 7

The magnitude of the induced e.m.f. is proportional to the rate of change of magnetic flux linkage.

Question 8

Lenz’s Law

Answer 8

Any induced e.m.f. will be established in a direction so as to produce effects which oppose the change (movement) that is producing it.

Question 9

Magnetic Flux and Magnetic Flux Linkage

Answer 9

Magnetic flux is the product of the magnetic flux density normal to a circuit and the cross-sectional area of that circuit. Magnetic flux linkage is then the product of magnetic flux and the number of turns in the coil that makes up this circuit.