Electric And Magnetic Fields

Question 1

Electric field strength

Answer 1

Force per unit positive charge

Question 2

Magnetic field strength

Answer 2

Flux density perpendicular to a wire is the magnetic force on a wire / length of wire x current flowing through the wire

Question 3

Tesla

Answer 3

Flux density that causes a force of one newton on a wire of length one metre carrying a current of 1 amp

Question 4

Magnetic flux

Answer 4

Magnetic flux density x cross sectional area perpendicular to the field

Question 5

Magnetic flux density

Answer 5

the amount of magnetic flux in an area taken perpendicular to the magnetic flux’s direction

Question 6

Weber

Answer 6

the electromotive force of one volt in a circuit of one turn generated or removed in one second

Question 7

Faraday’s law of induction

Answer 7

the law of electromagnetism predicting how a magnetic field will interact with a circuit to make an electromotive force (electromagnetic induction)

Question 8

how do electrons behave in an AC current

Answer 8

the electrons oscillate around their mean position and do

not travel along the wire at all

Question 9

why is ac current used

Answer 9

it is used in all countries for mains supply as it produces a variable magnetic field

Question 10

what are electric fields created by

Answer 10

electric charges

Question 11

What do the electric field lines show in an electric field

Answer 11

the arrows show the direction of a positive charge (arrows go from positive to negative)

Question 12

Coulomb’s law

Answer 12

F=(Qq)/4πε0r^2 the force between two point charges

Question 13

equation for electric field strength of a point charge

Answer 13

E=Q/4πε0r^2

Question 14

equation to find the magnitude of the uniform electric field strength between charged parallel plates?

Answer 14

E=V/d

Question 15

4 similarities between Gravitational fields and Electric fields

Answer 15

1. field lines show the path of mass/charge in a field
2. inverse square law of force; Newton’s law of gravitation and coulombs law of force
3. have field strength equations; g=F/m and E=F/Q
4. have uniform and radial fields with equations

Question 16

3 differences between Gravitational fields and Electric fields

Answer 16

1. gravitational fields act between any two masses; electric fields act only between two charged particles
2. forces which act: in gravity its always attractive and in electric fields they attract and repel
3. the constant of proportionality is different

Question 17

what is Flemmings Left Hand rule used for?

Answer 17

determining the force on the current conductor placed at right angles to the magnetic

Question 18

what is the equation F=BQv used for?

Answer 18

finding the force on a charged particle travelling at right angles to a uniform magnetic field