Electric Fields

Question 1

What is an electric field associated to?

Answer 1

Charge

Question 2

Define electric field strength

Answer 2

The force that would act on a unit charge placed at a point in the field.

Question 3

What is the relationship between electric field strength and the distance?

Answer 3

E ∝ 1/r^2

Question 4

What is the pattern of electric field lines?

Answer 4

Radial

Question 5

What is the direction of an electric field?

Answer 5

The direction of the force that would act on a positive charge placed in the field.

Question 6

Give two factors that can affect the size of the electric field between two plates.

Answer 6

• The pd across the plates.

- The plate separation.

Question 7

What is the relationship between electric field strength and the position between the plates?

Answer 7

They are independent

Question 8

What is the relationship between electric field strength and the pd across the plates?

Answer 8

E ∝ V

Question 9

What is the relationship between electric field strength and the separation of the plates?

Answer 9

E ∝ 1/d

Question 10

When does the formula E=V/d apply?

Answer 10

When two plates are parallel

Question 11

When does an electric field do work on a positive charge?

Answer 11

When the charge moves in the direction of the electric field.

Question 12

What is the relationship between electric field lines and equipotential surfaces?

Answer 12

They are perpendicular to each other.

Question 13

What is the relationship between field strength and potential?

Answer 13

Field strength = -Potential gradient (-dV/dx)

Question 14

What is the relationship between potential and charge?

Answer 14

V ∝ Q

Question 15

What is the relationship between potential and distance?

Answer 15

V ∝ 1/r

Question 16

How is potential calculated?

Answer 16

V = (1/4πε0)(Q/r)

Question 17

What is ε0?

Answer 17

The permittivity of free space

Question 18

How is the potential at the surface of a sphere calculated?

Answer 18

V = (1/4πε0)(Q/a)

Question 19

How is electrical potential energy calculated?

Answer 19

EPE = qV

Question 20

What does a negative EPE show?

Answer 20

An attractive system

Question 21

How is electric field strength in a radial field calculated?

Answer 21

E = (1/4πε0)(Q/r^2)

Question 22

How is the force between two objects calculated?

Answer 22

F = (1/4πε0)(Qq/r^2)

Question 23

Is field potential scalar of vector?

Answer 23

Scalar

Question 24

Is field strength scalar or vector?

Answer 24

Vector

Question 25

What is the unit of W?

Answer 25

Joules

Question 26

When is work done by the field?

Answer 26

When W is negative

Question 27

When is work done against the field?

Answer 27

When W is positive

Question 28

How is work done calculated?

Answer 28

W = qΔV

Question 29

How is the force on a charge in an electric field calculated?

Answer 29

F = qE

Question 30

When is the force of an electric field positive?

Answer 30

When the force is repulsive

Question 31

When is the force of an electric field negative?

Answer 31

When the force is attractive

Question 32

What type of shape will an electron moving through an electric field produce?

Answer 32

A parabola going towards the positive plate.

Question 33

What is Coulomb’s Law?

Answer 33

F = (1/4πε0)(Q1Q2/r^2)

Question 34

How is electric field strength calculated?

Answer 34

E = F/Q

Question 35

How is electric field strength in a uniform field calculated?

Answer 35

E = V/d