Electric Fields

Question 1

When calculating the force between two particles, what can air be treated as?

Answer 1

A Vaccum

Question 2

For a charged sphere the charge can be assumed to be what part of the sphere?

Answer 2

The Centre

Question 3

Which is stronger?
Gravitational force of subatomic particles or the electrostatic force

Answer 3

Electrostatic force

Question 4

Electric Field lines always go from ____________ to ___________

Answer 4

Positive charge to a negative charge

Question 5

What is electric fields strength

Answer 5

The force per unit charge on a small positive test charge acting at a point in an electric field

Question 6

What is the trajectory of a particle entering perpendicularly to a uniform field

Answer 6

Parabolic

Question 7

How is electric potential related to electric field strength

Answer 7

E = Chnage in V / Change in R

The change in electric potential in respect to radius length

Question 8

A +4 nc and a +6 nc charges have a distance of 50x

Draw the Corresponding electric field

Answer 8

1) A = 4/6B & A+B = 50x
2) 50x = 10/6B
3) B = 30X —-> A = 20x
4) A needs to have less field lines due to a smaller magnitude of charge

Question 9

What do electric field lines show?

Answer 9

.the path of a free positive test charge would follow in that electric field

Question 10

Name an example that produces a:

.Uniform electric field

.Radial Electric field

Answer 10

.Parallel plates

.Point charges

Question 11

Write out the derivation for E = V/D

Answer 11

VM^-1
only in parallel electric field

Question 12

What is electric potential

Answer 12

Work done per unit charge on a small positive test charge when it is moved from 1 point in a field to infinity

Question 13

What is Coulomb’s Law

What does negative and positive values signify?

Answer 13

For 2 point charges the force between them is proportional to the product if the magnitude of the charges & inversely proportional to the square of the distances between them

F = Negative then its an attraction
F = Positive then its a repulsion

Question 14

Name the conditions for coulomb’s law

Answer 14

1) Charges must have a spherically symmetrical charge distribution
2) Charges must not overlap —> has to be 2 distinct point charges
3) Charges must be stationary with respect to one another

Question 15

How do you derive the field strength for a radial field equation

Answer 15

Coulomb’s law & E = F/q
where q is equal to the test charge

Question 16

How do you derive the electric potential equation

Answer 16

Coulomb’s law & Wd = Vq

Question 17

Explain the difference in how insulation and conductive metals distribute charge

Answer 17

Insulating metals —> No free electrons , easy to gain and loose charge on the metals surface

Conductive metals —> Free electrons move throughout the metal, only can be charged by isolating it from the earth, as electrons flow between the metal and the earth otherwise

Question 18

Even if a point between electric fields has net 0 electric field strength between 2 alike charges

Why does it still take/cost energy to move a proton from that point to infinity

Answer 18

Electric potential and field strength are not the same
electric potential at infinity is zero
There still is a positive electric potential at that point so Work must be done on the proton

Question 19

Name a difference between an Electric and Gravitational field

Answer 19

Grav field only shows attraction

Electric field can show attraction and repulsion

Question 20

Answer 20

Question 21

Answer 21

1) Terminal Velocity means there is no resultant force acting on the object
2) PD increases increases the magnitude of charge accumulating on the positive plate
3)This creates an electrostatic force acting in a direction which opposes the motion
4) Electrostatic forces increase when pd increases
5) Resultant force acts upwards causing the drop to accelerate in the opposite direction to motion
6) so negatively charged drop speed decreases until stationary.
7) Drop remains stationary when Weight = electrostatic force from positive plate.

Question 22

What is meant by an electric field

Answer 22

region where a charged particle experiences a force

Question 23

Answer 23