6.2 Electric Fields

Question 1

Electric Field

Answer 1

A region in which charged bodies will experience a force

Question 2

What causes an electric field

Answer 2

A charge

Question 3

How to model a charged sphere

Answer 3

Can be modelled as a point charge when considering outside of the sphere

Question 4

How electric field lines work

Answer 4

They show the movement of a positive particle. The closer they are the stronger the field.

Question 5

Basic formula for electric field strength

Answer 5

E = Force per Charge (F/Q)

Question 6

What is the force between two charges proportional to

Answer 6

The product of their charges,

1 / distance^2

Question 7

What is the electric field strength proportional to

Answer 7

charge,

1/distance^2

Question 8

Similarities between an electric and gravitational field in terms of their strength (2)

Answer 8

Both proportional to the value of the charge/mass at a point which is causing the field
Both proportional to 1/r^2

Question 9

Difference between electric and gravitational fields

Answer 9

Gravitational fields are always attractive whereas electric fields can also be repulsive

Question 10

Fundamentally what is an electric field

Answer 10

One example of a field giving rise to a force

Question 11

Equation for electric field strength between to parallel oppositely charged plates

Answer 11

E = V/d

Question 12

What is special about a uniform electric field

Answer 12

The force/field strength is the same at any point

Question 13

Motion of a stationary particle when put in a uniform field

Answer 13

Accelerates towards one of the plates depending on its charge

Question 14

Motion of a particle moving perpendicular to a field that moves into the field

Answer 14

Will continue with same horizontal speed but will accelerate towards one of the plates. Forms a parabola.

Question 15

Permittivity

Answer 15

Measure of a materials ability to resist an electric field

Question 16

Equation for capacitor in terms of permittivity

Answer 16

εA/d

Question 17

How relative permittivity relates to actual permittivity

Answer 17

Multiply relative permittivity by the permittivity of free space (ε0) to obtain actual permittivity

Question 18

Electric Potential

Answer 18

Work done per unit positive charge to move that charge from infinity to a point in an electric field

Question 19

Electric Potential Energy of a charged object

Answer 19

The work done to move that charge from infinity to it’s current position

Question 20

Electric potential at infinity

Answer 20

zero

Question 21

How is potential difference related to electric fields

Answer 21

The electric potential at a point is the potential difference between that point and infinity
22

Question 22

What is the area under a force-distance graph between two points (with regards to electric fields)

Answer 22

The work done to move from one of the points to the other