18.4 Electric Field: Concept of a Field Revisited

Two particles with charges +2q and +q are separated by a distance r. The +2q particle has an electric field E at distance r and exerts a force F on the +q particle. Use this information to answer questions 31–32.

What is the electric field of the +q particle at the same distance and what force does it exert on the +2q particle?

1. E/2, F/2
2. E, F/2
3. E/2, F
4. E, F

The direction of the electric field of a negative charge is

1. inward for both positive and negative charges.
2. outward for both positive and negative charges.
3. inward for other positive charges and outward for other negative charges.
4. outward for other positive charges and inward for other negative charges.

When a positively charged particle exerts an inward force on another particle P, what will be the charge of P?

1. positive
2. negative
3. neutral
4. cannot be determined

Suppose that the force exerted on an electron is 5.6×10⁻¹⁷ N, directed to the east.

1. Find the magnitude of the electric field that exerts the force.
2. What will be the direction of the electric field?
3. If the electron is replaced by a proton, what will be the magnitude of force exerted?
4. What will be the direction of force on the proton?

What is the magnitude and direction of the force exerted on a $3.50 \mu \text{C}$ charge by a 250 N/C electric field that points due east?

(a) What magnitude point charge creates a 10,000 N/C electric field at a distance of 0.250 m? (b) How large is the field at 10.0 m?

(a) Find the magnitude and direction of an electric field that exerts a $4 . \text{80} \times \text{10}^{- \text{17}} \text{N}$ westward force on an electron. (b) What magnitude and direction force does this field exert on a proton?