Q: What is the electric flux through the surface $$A_1$$ that encloses all three objects in the figure, given $$O_1 = +1.0$$\ \mu\mathrm{C}$$, O_2$ = -2.0\ \mu\mathrm{C}$$, and $$O_3 is $$neutral?

$$-1.0 \times 10$$^{-6}$$\ \mathrm{C}/\$$varepsilon_0$$

Q: A $$+2.0\ \mu\mathrm{C}$$ charge and a $$-2.0\ \mu\mathrm{C}$$ charge are placed $$10\ \mathrm{cm}$$ apart. What is the electric field at the midpoint between them?

$$7.2 \times 10^6$\ \mathrm{N/C}$$, directed from positive to negative

Q: A $$+5.0\ \mu\mathrm{C}$$ charge is placed at the origin. What is the electric field at a point $$0.20\ \mathrm{m}$$ away from the charge?

$$1.1 \times 10^6$\ \mathrm{N/C}$$

Question 1

Three positive charges of $$+17.0\ \mu\mathrm{C}$$ are placed at the corners of an equilateral triangle with sides of $$15.0\ \mathrm{cm}. $$What is the magnitude of the net force on any one charge due to the other two? Use $$k = 9.0 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$.

Accepted Answer

$$170\ \mathrm{N}$$

Question 2

Two point charges, $$Q_1 = -32$$\ \mu\mathrm{C}$$ and Q_2$ = +45\ \mu\mathrm{C}$$, are separated by $$12\ \mathrm{cm}. At $$what distance from $$Q_1 is $$the electric field zero?

Accepted Answer

$$8.0\ \mathrm{cm}$$

Question 3

A cube of side $$8.50\ \mathrm{cm} is $$placed in a uniform electric field $$E = 7.50 	imes 10^3$\ \mathrm{N/C}$$ with edges parallel to the field lines. What is the net electric flux through the cube?

Accepted Answer

$$0\ \mathrm{N\cdot m^2$/C}$$

Question 4

What is the electric flux through the surface $$A_1$$ that encloses all three objects in the figure, given $$O_1 = +1.0$$\ \mu\mathrm{C}$$, O_2$ = -2.0\ \mu\mathrm{C}$$, and $$O_3 is $$neutral?

Accepted Answer

$$-1.0 	imes 10$$^{-6}$$\ \mathrm{C}/\$$varepsilon_0$$

Question 5

What is the electric flux through the surface $$A_2$$ that encloses only the neutral object $$O_3$$?

Accepted Answer

$$0$$

Question 6

At a point midway between a $$-8\ \mu\mathrm{C}$$ and a $$+5.8\ \mu\mathrm{C}$$ charge separated by $$6.0\ \mathrm{cm}$$, what is the direction of the net electric field?

Accepted Answer

Toward the $$-8\ \mu\mathrm{C}$$ charge

Question 7

Which equation correctly expresses Coulomb’s Law for the force between two point charges $$q_1$$ and $$q_2$$ separated by distance $$r$$?

Accepted Answer

$$F = k \dfrac{q_1$ q_2$}{r^2$}$$

Question 8

Two positive charges $$Q = 4.7\ \mu\mathrm{C}$$ are placed as shown in the figure. What is the direction of the net electric field at point A?

Accepted Answer

Up and to the right

Question 9

A $$+2.0\ \mu\mathrm{C}$$ charge and a $$-2.0\ \mu\mathrm{C}$$ charge are placed $$10\ \mathrm{cm}$$ apart. What is the electric field at the midpoint between them?

Accepted Answer

$$7.2 	imes 10^6$\ \mathrm{N/C}$$, directed from positive to negative

Question 10

A cube is placed in a uniform electric field such that the field lines are parallel to the cube’s faces. What is the electric flux through one face if the net flux through the cube is zero?

Accepted Answer

The flux through one face is equal in magnitude and opposite in sign to the flux through the opposite face.

Question 11

Which of the following best describes the direction of the electric field created by a positive point charge?

Accepted Answer

Radially outward from the charge

Question 12

If the distance between two point charges is doubled, what happens to the magnitude of the force between them?

Accepted Answer

It becomes one-fourth as large

Question 13

A $$+5.0\ \mu\mathrm{C}$$ charge is placed at the origin. What is the electric field at a point $$0.20\ \mathrm{m}$$ away from the charge?

Accepted Answer

$$1.1 	imes 10^6$\ \mathrm{N/C}$$

Question 14

Which of the following is the correct formula for the electric potential $$V at a $$distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$V = k \dfrac{q}{r}$$

Question 15

A neutral object is placed near a positively charged object. What happens to the neutral object?

Accepted Answer

It is attracted to the charged object due to polarization.

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