Electromag

Question 1

Superposition principle

Answer 1

The force experienced by charge q is the sum of forces due to all charges Q1, Q2 and Q3

Question 2

Electric field

Answer 2

A field in which a test charge q experiences a force F

Question 3

Conductor

Answer 3

Charges can move around freely in conductors

Question 4

Electric charge is _ inside a conductors bulk

Answer 4

0, otherwise charges inside the conductor would be moving

Question 5

Circulation law or circuital law

Answer 5

The path integral of the electric field is Always 0 in electrosatics

Question 6

Equipotential surface

Answer 6

A surface defined by V(r) = constant. E is perpendicular to surface.

Question 7

The negative gradient of …

Answer 7

the potential in any direction is the component of the electric field in that direction

Question 8

Electrostatic potential

Answer 8

Units of volts, potential energy per unit charge, uniquely defined, scalar.

Question 9

Electric dipole

Answer 9

A pair of equal but opposite charges

Question 10

Dipole moment

Answer 10

P = Qd for a pair of charges +Q and -Q separated by distance |d|. d points from -Q to +Q

Question 11

Ideal dipole

Answer 11

Dipole in which the distance between charges is negligibly small (far field approximation)

Question 12

Capacitance

Answer 12

Charge stored per unit voltage

Question 13

Wherever there is an electric field..

Answer 13

There is energy stored inside it

Question 14

Electric current

Answer 14

Flow of charge per unit time

Question 15

Electromotive force

Answer 15

Amount of energy gained per unit charge that passes through in the uphill direction.

Question 16

A charged particle in a uniform B-field has a constant kinetic energy because

Answer 16

Force is perpendicular to velocity and so no work is done by the B field

Question 17

Cyclotron frequency

Answer 17

The angular frequency of a free charged particle in a circular orbit in a B field

Question 18

Lorentz force

Answer 18

The electromagnetic force experienced by a charged particle when it moves through magnetic (and electric) fields

Question 19

Gauss’ law for B

Answer 19

Magnetic flux through any closed surface is 0. Magnetic field lines do not begin or end, they form closed loops. Magnetic charges do not exist

Question 20

Magnetic field’s lack of path independence means..

Answer 20

B is not a gradient of scalar potential

Question 21

Ampere’s law

Answer 21

Path integral of magnetic field round a close loop is directly proportional to the sum of the current in the loop

Question 22

Magnetostatics

Answer 22

A regime of physics for which current distributions remain fixed in time

Question 23

Biot Savart Law

Answer 23

How the field is related to a current loop. Always satisfies Amperes law and Gauss’ law for B

Question 24

Solenoid magnetic field characteristics

Answer 24

-homogenous field inside loop
-0 outside loop

Question 25

Magnetic field inside solenoid derivation assumptions

Answer 25

-solenoid infinitely long so avoid end effects -cylindrical symmetry and gauss’ law mean radial B is zero -neglect any current flowing parallel to axis

Question 26

Faradays law

Answer 26

An emf is induced for time varying magnetic flux. (Summarises phenomenology with circuits.

Question 27

E in one reference frame..

Answer 27

Is B in another.

Question 28

Lenz’s law

Answer 28

When an induced current is set up in any electromagnetic system, it always acts in such a way as to oppose the change which produced it.