Electric Fields

Question 1

Define Coulombs Law

Answer 1

The magnitude of the force between 2 point charges in a vacuum is directly proportional to the product of their charges and inversely proportional to the square of the distance between the charges

Question 2

Charges of the same sign… Charges of opposite signs…

Answer 2

Same sign: Repel Opposite sign: Attract

Question 3

Compare the magnitude of electrostatic forces vs gravitational forces between 2 subatomic particles

Answer 3

Electrostatic forces are magnitudes bigger As mass of subatomic particles is tiny compared to the charge they carry

Question 4

Define a bodies Field Line

Answer 4

The path a free positive test charge would follow if placed near a body with a bigger charge

Question 5

What is the electric field pattern for 2 oppositely charged point charges

Answer 5

Question 6

What is the electric field pattern for a Positive point charge

Answer 6

Question 7

What is the electric field pattern for a negative point charge

Answer 7

Question 8

What is the electric field pattern for a charged plate and a point charge that have opposite charges

Answer 8

Question 9

What is the electric field pattern for 2 oppositely charged parallel plates

Answer 9

Question 10

Define Electric Field Strength

Answer 10

The force per unit charge experienced by an object in an electric field

Question 11

How does Electric field strength vary in a uniform and radial field

Answer 11

Constant in a uniform field

Varies in a radial field

Question 12

What is (4πΣ₀)^-1

Answer 12

8.99x10⁹

Question 13

Are these quantities scalar or vector

Electric Field Strength

Electric Potential

Electric Potential Energy

Answer 13

Electric Field Strength - Vector

Electric Potential - Vector

Electric Potential Energy - Scalar

Question 14

What is the electric field pattern for a uniform field

Answer 14

Question 15

What is the derivation for Work Done to move a charge between plates equation

Work Done = Qx(Change in V)

Answer 15

Work Done = Fxd

E=F÷Q, so F=EQ

E=(Change in V) ÷ d, so d=(Change in V) ÷ E

Work Done = EQ x (Change in V)/E, E’s cancel

Work Done = Qx(Change in V)

Question 16

What happens if you fire a point charge at a right angle to a uniform field

Answer 16

Particle will accelerate towards the side with an opposite charge with a parabolic shape

Question 17

Define Electric Potential

Answer 17

The work done per unit positive charge on a positive test charge when it is moved from infinity to that position

Question 18

How does Electric Potential vary with distance from a positive point charge

Answer 18

For a positive point charge, the force is repulsive

So all values for V will be positive

As to get further from zero (closer to the point charge) more energy would be needed to move against the repulsive force that is getting stronger

Question 19

How does Electric Potential vary with distance from a negative point charge

Answer 19

When the charge is negative, the force is attractive

So all values of V are negative just like in a gravitational field

As a positive charge can lose energy to move away from 0 (towards the negative charge)

Question 20

What is the gradient of a V-r graph at a point

Answer 20

The electric field strength at that point

Question 21

Define electric Potential Difference

Answer 21

The energy required to move a unit charge between 2 points

Question 22

Define electric potential energy

Answer 22

The work done on a positive test charge when it is moved from infinity to that position

Question 23

What is an equipotential surface

Answer 23

A surface that the electric potential is the same everywhere

No work is done to move along it

Question 24

What is the area under an E-r graph

Answer 24

Electric potential difference