2. Fields (electrical) / Capacitors

Question 1

Electric field strength

Answer 1

the force per unit charge

Question 2

Uniform electric field strength

Answer 2

the volts per meter

Question 3

Which way does charge flow

Answer 3

postive to negative

Question 4

Electric field strength equation

Answer 4

E = F / Q

Question 5

What quantity is electric field strength

Answer 5

Vector

Question 6

What quantity is potential

Answer 6

Scalar

Question 7

Force upon charges equation

Answer 7

F = 9x10⁹ (Q1 x Q2 / r²)

Question 8

Electrical Field strength equation 2

Answer 8

E= 9x10⁹ x (Q/r²)

Question 9

Voltage definition

Answer 9

The energy transferred per unit charge

Question 10

Potential equation

Answer 10

Ve = 9x10^9 x (Q/r)

Question 11

Potential definition

Answer 11

The work done is bringing unit positive charge from infinity to a point

Question 12

What happens when an electron moves past a negatively charged particle?

Answer 12

The electron looses KE because it is fighting against the repulsive force

Question 13

Change in potential energy equation

Answer 13

W = q x change in Ve

Question 14

What is electrical field strength on a Ve against r graph

Answer 14

the negative gradient

Question 15

What is the potential difference on a E against r graph

Answer 15

The area under the line

Question 16

Potential energy of a point charge equation

Answer 16

qVe = 9x10^9 x (Q1 x Q2 / r )

Question 17

What does the potential energy at infinity equal to?

Answer 17

The KE

Question 18

What is a uniform electric field?

Answer 18

A field that has the same strength electric field all the way around

Question 19

How would you change the electric field strength in a uniform situation

Answer 19

increase the charge on the plates
change the distance between the plates

Question 20

Uniform electric equation

Answer 20

E = V /d

Question 21

Definition of capacitance

Answer 21

amount of charge stored per unit of potential difference

Question 22

Capacitance equation

Answer 22

C= Q / V

Question 23

Parallel capacitors equation

Answer 23

C = 8.85x10^-12 x A / d

A = area of plates
d = distance between plates

Question 24

Electric field in a Capacitor

Answer 24

E = V / d

Question 25

Work done in capacitor

Answer 25

W = change in Q x V

Question 26

Energy stored in capacitor

Answer 26

½ CV²

Question 27

How do you change the capacitance without changing the dimensions

Answer 27

Add a dielectric Change the type of material

Question 28

As charging Q against T graph

Answer 28

Increasing to a maximum then levelling off

Question 29

As discharging Q against T and I against T

Answer 29

Decreasing exponential graph

Question 30

Discharging equations

Answer 30

Q/V/I = (inital Q/V/I) x e^-t/RC

Question 31

What is RC

Answer 31

RC = time constant also time to reduce 37% of value

Question 32

What is a capacitor

Answer 32

Two parallel conducting plates separated by an insulator

Question 33

How do the graphs for charging and discharging capacitors differ?

Answer 33

Charging has a positive reciprocal gradient compared to the negative reciprocal gradient of discharging

Question 34

What is coulombs law

Answer 34

The force experienced between two point charges is proportional to the product of their charges and inversly proportional to the distance

Question 35

For a charged sphere where is charge acting

Answer 35

at the centre of the sphere

Question 36

What is air treated as when using the electric fields equations

Answer 36

A vaccum

Question 37

Definition of electric potential

Answer 37

The potential energy per unit charge of a positive charge

Question 38

How do you measure uncertainty from lots of values

Answer 38

Range / 2