Q: Refer to the first image. What is the magnitude of the force on the charge $$Q = +17\ \mathrm{nC}$$ due to the other point charges? ($$k = 8.99 \times 10^9$\ \mathrm{N}\cdot\mathrm{m}^2/\mathrm{C}^2)$$

$$1.6 \times 10$$^{-4}$$\ \mathrm{N}$$

Q: An electron is placed in an electric field of intensity $$700\ \mathrm{N/C}. $$What is the magnitude and direction of the acceleration of this electron? ($$m_e = 9.11 \times 10$$^{-31}$$\ \mathrm{kg}$$, $$e = 1.60 \times 10$$^{-19}$$\ \mathrm{C})$$

$$1.23 \times 10$$^{14}$$\ \mathrm{m/s^2$}$$, opposite to the electric field

Question 1

A cylindrical metal wire of length $$L = 40.0\ \mathrm{m}$$ and radius $$r = 4.0\ \mathrm{mm} is $$connected to a $$16.0\ \mathrm{V}$$ source. The resistivity of the metal is $$ho = 1.68 	imes 10$$^{-8}$$\ \Omega\cdot\mathrm{m}. $$What is the current through the wire?

Accepted Answer

$$68\ \mathrm{nA}$$

Question 2

Suppose you have two negative point charges. As you move them farther apart, the potential energy of the system relative to infinity:

Accepted Answer

Increases

Question 3

A point charge $$Q is $$located a short distance from a point charge $$3Q. If $$the electrical force on $$Q is$$ $$F$$, what is the electrical force on $$3Q$$?

Accepted Answer

$$F$$

Question 4

A wire of resistivity $$\rho is $$replaced by a wire of the same material but twice as long. If the resistance is to remain the same, what must be the diameter of the new wire?

Accepted Answer

$$\sqrt{2}$$ times the diameter of the original wire

Question 5

Refer to the first image. What is the magnitude of the force on the charge $$Q = +17\ \mathrm{nC}$$ due to the other point charges? ($$k = 8.99 	imes 10^9$\ \mathrm{N}\cdot\mathrm{m}^2/\mathrm{C}^2)$$

Accepted Answer

$$1.6 	imes 10$$^{-4}$$\ \mathrm{N}$$

Question 6

An electron is placed in an electric field of intensity $$700\ \mathrm{N/C}. $$What is the magnitude and direction of the acceleration of this electron? ($$m_e = 9.11 	imes 10$$^{-31}$$\ \mathrm{kg}$$, $$e = 1.60 	imes 10$$^{-19}$$\ \mathrm{C})$$

Accepted Answer

$$1.23 	imes 10$$^{14}$$\ \mathrm{m/s^2$}$$, opposite to the electric field

Question 7

A $$6.0\ \mu\mathrm{F}$$ capacitor is connected in series with a $$5.0 	imes 10^6$\ \Omega$$ resistor and a $$15\ \mathrm{V}$$ battery. What is the current when the capacitor has reached $$20\% of $$its maximum charge?

Accepted Answer

$$6.5\ \mu\mathrm{A}$$

Question 8

A $$-6.0\ \mu\mathrm{C}$$ charge moves through a potential difference of $$3.0\ \mathrm{mV}. $$How much kinetic energy does it gain?

Accepted Answer

$$18\ \mathrm{nJ}$$

Question 9

The electric field $$1.5\ \mathrm{cm}$$ from a small charged object points toward the object with a magnitude of $$180,000\ \mathrm{N/C}. $$What is the charge on the object? ($$k = 8.99 	imes 10^9$\ \mathrm{N}\cdot\mathrm{m}^2/\mathrm{C}^2)$$

Accepted Answer

$$-5.0\ \mathrm{nC}$$

Question 10

Refer to the second image. Three equal negative point charges are placed at three corners of a square of side $$d. $$Which arrow represents the direction of the net electric field at the center?

Accepted Answer

B

Question 11

Refer to the third image. Four resistors are connected across an $$8\ \mathrm{V}$$ battery as shown. What is the current through the battery?

Accepted Answer

$$0.9\ \mathrm{A}$$

Question 12

Refer to the fourth image. What is the equivalent capacitance between points $$a$$ and $$b$$?

Accepted Answer

$$7.1\ \mu\mathrm{F}$$

Question 13

A parallel-plate capacitor consists of two square plates, $$1.0\ \mathrm{cm} 	imes 1.0\ \mathrm{cm}$$, separated by $$1.0\ \mathrm{mm}$$ and filled with teflon ($$\kappa = 2.1$$, $$\$$epsilon_0$$ = 8.85 	imes 10$$^{-12}$$\ \mathrm{C}^2/\mathrm{N}\cdot\mathrm{m}^2). $$What is the capacitance?

Accepted Answer

$$1.9\ \mathrm{pF}$$

Question 14

Refer to the fifth image. Four dipoles, each consisting of a $$+10\ \mu\mathrm{C}$$ and $$-10\ \mu\mathrm{C}$$ charge, are located in the $$xy-$$plane with their centers $$1.0\ \mathrm{mm}$$ from the origin. A sphere passes through the dipoles as shown. What is the electric flux through the sphere?

Accepted Answer

$$0.00\ \mathrm{N}\cdot\mathrm{m}^2/\mathrm{C}$$

Question 15

The electric field between the plates of a parallel-plate capacitor has magnitude $$E. $$The potential across the plates is maintained at constant voltage as the plates are pulled apart to twice their original separation. What is the new magnitude of the electric field?

Accepted Answer

$$E/2$$

Question 16

A $$+4.0\ \mu\mathrm{C}$$ point charge and a $$-4.0\ \mu\mathrm{C}$$ point charge are placed as shown in the figure. What is the potential difference $$V_A - V_B$$ between points $$A$$ and $$B$$? ($$k = 8.99 	imes 10^9$\ \mathrm{N}\cdot\mathrm{m}^2/\mathrm{C}^2)$$

Accepted Answer

$$0.00\ \mathrm{V}$$

Physics with Calculus Midterm Study Guide: Electric Forces, Fields, Circuits, and Capacitance

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