Electric Fields

Question 1

Coulomb’s law equation

Answer 1

F=Q1Q2/4piEor^2
F is force (N)
Q is change of object 1 and 2 (C)
Eo is permittivity of free space:8.85*10^-12m^-3kg^-1s^4A^2
r is distance between object 1 and 2 (m)

Question 2

When does Coulomb’s law hold true?

Answer 2

When we assume all charge at a single point

Question 3

For Coulomb’s law what charges can Q be if F is positive?

Answer 3

++ or - -

Question 4

For Coulomb’s law what charges can Q be if F is negative?

Answer 4

-+ or +-

Question 5

How to describe motion of charge if there is overall unbalanced force is toward x

Answer 5

Accelerating towards x

Question 6

What is the charge of the particle we use in field diagrams?

Answer 6

Positive

Question 7

Left hand rule is used for…..

Answer 7

Positive Charge

Question 8

Right hand rule is used for….

Answer 8

Negative charge

Question 9

Equation for force with charge and electric field.

Answer 9

F = QE
F is Force (N)
Q is charge (C)
E is electric field strength (NC^-1)

Question 10

Electric field strength definition

Answer 10

Force acting per unit positive charge in an electric field

Question 11

Electric field strength equation

Answer 11

E = Q/4piEor^2
E is electric field strength (NC^-1)
Q is charge of object (C)
Eo is permittivity of free space -8.85*10^-12
r is radius (m)

Question 12

Electric potential definition

Answer 12

The work done by external forces in bringing a unit positive charge (1C) from infinity to that point.

Question 13

Electric potential equation

Answer 13

V = Q/4piEor
V is electric potential (V)
Q is charge of object (C)
Eo is permittivity of free space: 8.85*10^-12
r is radius (m)

Question 14

How to find distance if closest approach

Answer 14

Ek=Ep field(QV)

Question 15

Work done in electric field equation

Answer 15

Ew = VQ
Ew is work done (J)
V is electric potential (V)
Q is charge (C)

Question 16

What type of field is an electric field?

Answer 16

Conservative field

Question 17

Conservative field definition

Answer 17

Work done in moving an object between two points in the field is independent of the path taken.

Question 18

Electrical potential and distance equation

Answer 18

V=Ed
Where V is electrical potential (V)
E is electric field strength (NC^-1)
And d is distance (m)

Question 19

Equation for acceleration of charged particles in field

Answer 19

a =QE/m
Where a is acceleration (ms^-2)
Q is charge of particle (C)
E is electric field strength (NC^-1)
m is mass of particle (kg)

Question 20

When talking about motion of charged particle of fields what should always be referred to

Answer 20

Balanced / unbalanced forces

Question 21

Combining of electrical potential equation from 2 charges

Answer 21

V(total) = Q1/4piEor + Q2/4piEor

Don’t ignore charges potential can be positive or negative.

Question 22

When explaining parabolic curve of electron in cathode ray tube, what points should be hit?

Answer 22

Unbalanced force in vertical direction, vertical acceleration.

Balanced force in horizontal direction, constant horizontal velocity.

Question 23

Can electric potential be -

Answer 23

Yes

Question 24

Combining of electric field strength equation from 2 charges

Answer 24

E(total) = Q1/4piEor^2 + Q2/4piEor^2
Don’t ignore charges