Q: A point charge $$q = +2.0\ \mu\mathrm{C} is $$placed at the origin. What is the magnitude of the electric field at a distance $$0.50\ \mathrm{m}$$ from the charge? $$(k = 8.99 \times 10^9$\ \mathrm{N\cdot m^2$/C^2$$})$

$$7.2 \times 10^4$\ \mathrm{N/C}$$

Q: A bumblebee in flight picks up a charge of $$+32\ \mathrm{pC}. $$What is the electric field $$5.0\ \mathrm{mm}$$ from the bee? $$(k = 8.99 \times 10^9$\ \mathrm{N\cdot m^2$/C^2$$})$

$$1.2 \times 10^5$\ \mathrm{N/C}$$

Question 1

A neutral plastic rod is rubbed with neutral animal fur. After rubbing, the rod has a charge of $$-1.5 	imes 10$$^{-6}$$\ \mathrm{C}$$ and the fur has $$+1.5 	imes 10$$^{-6}$$\ \mathrm{C}. $$How many electrons were transferred from the fur to the rod? $$(e = 1.602 	imes 10$$^{-19}$$\ \mathrm{C})$$

Accepted Answer

$$9.4 	imes 10$$^{12}$$

Question 2

Which of the following statements best explains why a lightning rod is pointed?

Accepted Answer

Charge accumulates more densely at sharp points, increasing the likelihood of discharge.

Question 3

A metal tray carrying $$-8\ \mathrm{nC} is $$touched to an identical neutral tray, then separated. What is the charge on each tray after separation?

Accepted Answer

$$-4\ \mathrm{nC}$$

Question 4

Which of the following best describes the difference between conductors and insulators?

Accepted Answer

Conductors have free electrons that can move throughout the material, while insulators have tightly bound electrons.

Question 5

A point charge $$q = +2.0\ \mu\mathrm{C} is $$placed at the origin. What is the magnitude of the electric field at a distance $$0.50\ \mathrm{m}$$ from the charge? $$(k = 8.99 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$})$

Accepted Answer

$$7.2 	imes 10^4$\ \mathrm{N/C}$$

Question 6

A dust speck with charge $$q = +1\ \mu\mathrm{C}$$ floats near a balloon with charge $$Q = +100\ \mu\mathrm{C}. $$The balloon pushes the dust with electric force $$F. $$How hard does the dust push on the balloon?

Accepted Answer

$$F$$

Question 7

Which of the following is NOT a property of electric field lines?

Accepted Answer

Field lines can cross each other.

Question 8

A bumblebee in flight picks up a charge of $$+32\ \mathrm{pC}. $$What is the electric field $$5.0\ \mathrm{mm}$$ from the bee? $$(k = 8.99 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$})$

Accepted Answer

$$1.2 	imes 10^5$\ \mathrm{N/C}$$

Question 9

Which process results in an object acquiring a charge opposite in sign to the charging object, without direct contact?

Accepted Answer

Induction

Question 10

Two identical point charges are placed $$1.0\ \mathrm{m}$$ apart and repel each other with force $$F. If $$each charge is doubled and the separation is tripled, what is the new force?

Accepted Answer

$$\dfrac{4}{9}F$$

Question 11

A positively charged comb is held near, but does not touch, a steel tray resting on a plastic cart. The far end of the tray is briefly touched with a finger (grounded), then the finger is lifted and the comb is removed. What is the final charge on the tray?

Accepted Answer

Negative

Question 12

Which of the following best describes the electric field inside a conductor at electrostatic equilibrium?

Accepted Answer

$$E = 0$$

Question 13

A small ball carrying charge $$-Q$$ hangs from a string between two vertical charged plates. When released from rest, what will the ball do?

Accepted Answer

Swing toward the positive plate

Question 14

Which of the following is true about the quantization of electric charge?

Accepted Answer

Any observable charge is an integer multiple of the elementary charge $$e$$

Question 15

A point charge $$q is $$placed halfway between two identical charges $$+Q$$ separated by distance $$2d. If $$the net force on each charge is zero, what is $$q in $$terms of $$Q$$?

Accepted Answer

$$-Q/4$$

Question 16

Which of the following best describes the direction of the electric field at a point midway between two equal negative charges?

Accepted Answer

Away from the midpoint, along the line joining the charges

Question 17

A person receives a shock after walking across a carpet and touching a metal doorknob. Which process is primarily responsible for the buildup of charge?

Accepted Answer

Friction

Question 18

Which of the following is a real-world example of polarization of insulators?

Accepted Answer

A charged balloon attracting neutral pieces of paper

Question 19

The electric field between two large, parallel, oppositely charged plates is best described as:

Accepted Answer

Uniform, with straight, parallel, and evenly spaced field lines

Electric Charge and Electric Field: Physics with Calculus Study Notes

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