Topic 7

Question 1

What is a force field?

Answer 1

A region in which a non-contact force is experienced by a corresponding interacting particle

Question 2

what is an electric field?

Answer 2

A region in which a charged particle will experience a non-contact force

Question 3

What is electric field strength?

Answer 3

The force per unit charge experienced by a charged particle when placed at that point in the field

Question 4

State the equation used to calculate the force a charge experiences in an electric field

Answer 4

Force = Electric Field Strength x Charge

F =EQ

Question 5

What law determines the magnitude of the electric force between two charges?

Answer 5

Coulomb’s Law

Question 6

State Coulomb’s law in words

Answer 6

The force between two charges is directly proportional to the product of their charges and inversely proportional to the square of their separation

Question 7

Give Coulomb’s law in equation form

Answer 7

F = kQq/r^2

Where k = 1 / 4πε₀

Question 8

Describe the electric field pattern around a positive point charge

Answer 8

A radial field, acting outwards

Question 9

Describe the electric field pattern around a negative point charge

Answer 9

A radial field, acting inwards

Question 10

What equation is used to calculate the electric field between parallel plates?

Answer 10

E=V/d

Question 11

What is electric potential?

Answer 11

The amount of energy required to move a positive test charge from infinity to a given point in an electric field

Question 12

How do you calculate electric potential for a radial field?

Answer 12

V=kQ/r

Where k = 1 / 4πε₀

Question 13

What are equipotentials?

Answer 13

Equipotentials are lines along which the electric potential remains the same

Question 14

How do you calculate the work done in moving a charge along an equipotential?

Answer 14

No work is done when moving a charge along an equipotential since the electric potential doesn’t change

Question 15

What does a capacitor do?

Answer 15

Capacitors are used to store charge in a circuit

Question 16

What two factors determine how much charge can be stored by a capacitor?

Answer 16

The potential difference across it

The capacitance

Question 17

What is capacitance?

Answer 17

Capacitance is a measure of how much charge can be stored by a capacitor per unit potential difference across it

Question 18

State the equation used to calculate the capacitance from the charge and potential difference

Answer 18

Capacitance = Charge / Potential Difference

C=Q/V

Question 19

What is the unit of capacitance?

Answer 19

C/V or Farad

Question 20

What is represented by the area under a capacitor’s charge-potential graph?

Answer 20

The energy stored by a capacitor

Question 21

What is represented by the gradient of a capacitor’s charge-potential graph?

Answer 21

Capacitance

Question 22

Give three equations to calculate the energy stored by a capacitor

Answer 22

W = 1/2QV
W = 1/2CV^2
W = 1/2 Q^2 / C

Question 23

what value is given by the product of resistance and capacitance?

Answer 23

The time constant of the circuit

Question 24

What does the time constant of a cicuit tell you?

Answer 24

The time the capacitor will take to reach 63% of its total charge, and the time taken for it to discharge to 37% of its full charge