Q: A resistor has color bands yellow, violet, red, and gold. What is its resistance and tolerance?

$$4.7 \times 10^2$ \Omega$$, 5\% tolerance

Question 1

A charged sphere creates an electric field in the space around it. If a test charge $$q_0 is $$placed at a distance $$r$$ from the center of the sphere, what is the magnitude of the electric field at that point?

Accepted Answer

$$E = \frac{Q}{4\pi\$$epsilon_0$$ r^2$}$$

Question 2

Which of the following statements about electric field lines is correct?

Accepted Answer

Electric field lines are closer together where the field is stronger.

Question 3

A point charge $$q is $$placed at the center of a spherical Gaussian surface. According to Gauss's law, what is the total electric flux through the surface?

Accepted Answer

$$\Phi_E = \frac{q}{\$$epsilon_0$$}$$

Question 4

Refer to the diagram with five Gaussian surfaces and several point charges. For which two surfaces is the total electric flux zero?

Accepted Answer

S1 and S5

Question 5

A test charge $$q_0$$ moves from point $$a to $$point $$b in $$the electric field of a point charge $$q. $$What is the change in electric potential energy?

Accepted Answer

$$\Delta U = q_0$ (V_b - V_a)$$

Question 6

What is the electric potential at a distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$V = \frac{q}{4\pi\$$epsilon_0$$ r}$$

Question 7

Which of the following is true about the electric field just outside the surface of a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is perpendicular to the surface.

Question 8

A parallel-plate capacitor has plate area $$A$$ and separation $$d. $$What is its capacitance?

Accepted Answer

$$C = \frac{\$$epsilon_0$$ A}{d}$$

Question 9

If three capacitors $$C_1$$, $$C_2$$, and $$C_3$$ are connected in parallel, what is the equivalent capacitance?

Accepted Answer

$$C_{eq} = C_1$ + C_2$ + C_3$

Question 10

If two capacitors $$C_1$$ and $$C_2$$ are connected in series, what is the equivalent capacitance?

Accepted Answer

$$\frac{1}{C_{eq}} = \frac{1}{C_1$} + \frac{1}{C_2$}$$

Question 11

A current $$I$$ flows through a wire with cross-sectional area $$A. If a $$total charge $$\Delta Q$$ passes through in time $$\Delta t$$, what is the current?

Accepted Answer

$$I = \frac{\Delta Q}{\Delta t}$$

Question 12

A resistor has color bands yellow, violet, red, and gold. What is its resistance and tolerance?

Accepted Answer

$$4.7 	imes 10^2$ \Omega$$, 5\% tolerance

Question 13

Which equation correctly expresses Ohm's Law for a resistor?

Accepted Answer

$$V = IR$$

Question 14

What is the equivalent resistance of three resistors $$R_1$$, $$R_2$$, and $$R_3$$ connected in series?

Accepted Answer

$$R_{eq} = R_1$ + R_2$ + R_3$

Question 15

What is the equivalent resistance of three resistors $$R_1$$, $$R_2$$, and $$R_3$$ connected in parallel?

Accepted Answer

$$\frac{1}{R_{eq}} = \frac{1}{R_1$} + \frac{1}{R_2$} + \frac{1}{R_3$}$$

Question 16

According to Kirchhoff's loop rule, what must be true for the sum of the potential differences around any closed loop in a circuit?

Accepted Answer

$$\sum V = 0$$

Question 17

A parallel-plate capacitor is connected to a battery and then disconnected. If a dielectric is inserted between the plates, what happens to the stored energy?

Accepted Answer

The stored energy decreases.

Question 18

A circuit element has a potential difference $$V_{ab}$$ across it and a current $$I$$ passing through it. What is the power delivered to the element?

Accepted Answer

$$P = V_{ab} I$$

Question 19

An electron is shot horizontally into a region with a uniform electric field directed downward. What is the direction of the electron's acceleration?

Accepted Answer

Upward and constant

Question 20

Which of the following best describes the direction of electric field lines for a negative point charge?

Accepted Answer

They point radially inward toward the charge.

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