Electromagnetism Definitions

Question 1

Electric Field

Answer 1

The region that surrounds electrically charged particles in which a force is exerted on other electrically charged particles.
An electric fields exists around any point charge

Question 2

Electric Fields Strength

Answer 2

The electrical force per unit positive Charge. F=QE
Always talk about the field lines going in the direction of a positive charge if placed in that field

Question 3

Electrical Potential at a Point ( Electrostatic Charge)

Answer 3

The work done in moving unit positive charge from infinity to that point.

Energy moving a coulomb from infinity to the point you are talking about.

Question 4

ElectronVolt

Answer 4

The energy acquired when one electron accelerates through a potential difference of one volt.
1eV = 1.6 x10 ^-19 Joules

Question 5

Time Constabnt

Answer 5

If the capacitor is charging, it is the time taken to increase the charge stored to 63% of the difference between initial charge and full charge.

If the capacitor is discharging, it is the time taken for the capacitor to discharge to 37% of its initial charge.

Question 6

Capacitive Reactance

Answer 6

The opposition of a capacitor to changing current (i.e. a.c. current)

Question 7

Lenz’s Law

Answer 7

The induced EMF always opposes the change in current which causes it.

Question 8

INductance

Answer 8

The inductance of an inductor is one henry if an EMF of one volt is induced when the current is changing at a rate of one ampere per second.

It is a property of an inductor which depends on its design.

Question 9

Back EMF (Lenz’s Law)

Answer 9

The EMF produced when a magnetic field is generated around the coil of an inductor.

This occurs when the inductor is placed in a circuit in which the current is changing.

Question 10

Inductive Reactance

Answer 10

The opposition of an inductor to changing current (i.e. a.c. Current)