Electric Fields

Question 1

What is stated by coulombs law

Answer 1

Magnitude of the force between two point chargers in a vacuum is:
- Directly proportional to the product of their charges
- Inversely proportional to the square of the distance between the charges

Question 2

Compare the general magnitudes of electric and gravitational forces

Answer 2

• Magnitude of electrostatic forces between subatomic particles is magnitudes greater than magnitude of gravitational forces
• Because the masses of subatomic particles are smaller relative to the charges of subatomic particles

Question 3

Definition of electric field strength

Answer 3

• Force per unit charge experienced by an object in an electric field

Question 4

Equation for electric field strength in uniform field AND in uniform fields formed by parallel plates

Answer 4

E = F/Q (uniform)

E = V/d (parallel plates)

Question 5

How can parallel plates be used to determine the charge of a particle

Answer 5

• Fire a particle at right angles to the field and observe its path
• Charged particle will experience constant electric force either in or opposite to direction of field
• Causing particles to accelerate and so it follows a parabolic shape

Positive = Follow direction of field
Negative = Oppose direction of field

Question 6

Definition of absolute electric potential (V)

Answer 6

• Potential energy per unit charge of a positive point charge at a given point

Question 7

Describe magnitude of electric potential at surface of charge and at infinity

Answer 7

Surface of charge = Maximum

Infinity = zero

Question 8

How does the sign of the potential depend on sign of charge

Answer 8

Positive charge = positive potential (repulsive force)

Negative charge = potential is negative (attractive force) === similar to gravitational potential