18.5 Electric field: concept of a field revisited  (Page 3/6)

Two particles with charges +2 q and + q are separated by a distance r . The +2 q 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 +2 q particle?

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

When the + q particle is replaced by a +3 q particle, what will be the electric field and force from the +2 q particle experienced by the +3 q particle?

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

The force responsible for holding an atom together is

1. frictional
2. electric
3. gravitational
4. magnetic

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

Find the force exerted due to a particle having a charge of 3.2×10 ⁻¹⁹ C on another identical particle 5 cm away.

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?

Why must the test charge $q$ in the definition of the electric field be vanishingly small?

Are the direction and magnitude of the Coulomb force unique at a given point in space? What about the electric field?

What is the magnitude and direction of an electric field that exerts a $2\text{.}\text{00}\times {\text{10}}^{-5}\text{N}$ upward force on a $\mathrm{–1.75}\mu \text{C}$ charge?

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?

Calculate the magnitude of the electric field 2.00 m from a point charge of 5.00 mC (such as found on the terminal of a Van de Graaff).

(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?

Calculate the initial (from rest) acceleration of a proton in a $5\text{.}\text{00}\times {\text{10}}^6\text{N/C}$ electric field (such as created by a research Van de Graaff). Explicitly show how you follow the steps in the Problem-Solving Strategy for electrostatics.

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