Q: A $$3 \ \mu\mathrm{C}$$ charge is placed in an electric field of $$2 \times 10^4$ \ \mathrm{N/C}. $$What is the force experienced by the charge?

$$F = qE = 3 \times 10$$^{-6}$$ \times 2 \times 10^4$ = 0.06 \ \mathrm{N}$$

Q: A $$5 \ \mu\mathrm{F}$$ capacitor is connected in series with a $$10 \ \mu\mathrm{F}$$ capacitor. What is the equivalent capacitance?

$$C_{eq} = \left( \dfrac{1}{5 \times 10$$^{-6}$$} + \dfrac{1}{10 \times 10$$^{-6}$$} \$$right)^{-1}$$ = 3.33 \ \mu\mathrm{F}$$

Q: A proton moves perpendicular to a uniform magnetic field of $$0.2 \ \mathrm{T}$$ with a speed of $$3 \times 10^6$ \ \mathrm{m/s}. $$What is the magnitude of the magnetic force on the proton?

$$F = qvB = 1.6 \times 10$$^{-19}$$ \times 3 \times 10^6$ \times 0.2 = 9.6 \times 10$$^{-14}$$ \ \mathrm{N}$$

Q: A light wave in air has a frequency of $$6 \times 10$$^{14}$$ \ \mathrm{Hz}. $$What is its wavelength?

$$\lambda = \dfrac{c}{f} = \dfrac{3 \times 10^8$}{6 \times 10$$^{14}$$} = 5 \times 10$$^{-7}$$ \ \mathrm{m}$$

Question 1

A point charge of $$+2 \ \mu\mathrm{C} is $$placed at the origin. What is the magnitude of the electric field at a point $$0.5 \ \mathrm{m}$$ away from the charge in vacuum?

Accepted Answer

$$E = \dfrac{1}{4\pi\$$varepsilon_0$$} \dfrac{q}{r^2$} = \dfrac{9 	imes 10^9$ \cdot 2 	imes 10$$^{-6}$$}{(0.5)^2$} = 72,000 \ \mathrm{N/C}$$

Question 2

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

Accepted Answer

Electric field lines start on positive charges and end on negative charges.

Question 3

A $$3 \ \mu\mathrm{C}$$ charge is placed in an electric field of $$2 	imes 10^4$ \ \mathrm{N/C}. $$What is the force experienced by the charge?

Accepted Answer

$$F = qE = 3 	imes 10$$^{-6}$$ 	imes 2 	imes 10^4$ = 0.06 \ \mathrm{N}$$

Question 4

Which of the following best describes the difference between electric potential energy and electric potential (voltage)?

Accepted Answer

Electric potential energy is the energy a charge has due to its position, while electric potential is the energy per unit charge.

Question 5

A $$5 \ \mu\mathrm{F}$$ capacitor is connected in series with a $$10 \ \mu\mathrm{F}$$ capacitor. What is the equivalent capacitance?

Accepted Answer

$$C_{eq} = \left( \dfrac{1}{5 	imes 10$$^{-6}$$} + \dfrac{1}{10 	imes 10$$^{-6}$$} \$$right)^{-1}$$ = 3.33 \ \mu\mathrm{F}$$

Question 6

A $$12 \ \Omega$$ resistor and a $$6 \ \Omega$$ resistor are connected in parallel. What is the equivalent resistance?

Accepted Answer

$$R_{eq} = \left( \dfrac{1}{12} + \dfrac{1}{6} \$$right)^{-1}$$ = 4 \ \Omega$$

Question 7

A proton moves perpendicular to a uniform magnetic field of $$0.2 \ \mathrm{T}$$ with a speed of $$3 	imes 10^6$ \ \mathrm{m/s}. $$What is the magnitude of the magnetic force on the proton?

Accepted Answer

$$F = qvB = 1.6 	imes 10$$^{-19}$$ 	imes 3 	imes 10^6$ 	imes 0.2 = 9.6 	imes 10$$^{-14}$$ \ \mathrm{N}$$

Question 8

Which of the following best describes how electromagnetic waves are produced?

Accepted Answer

They are produced by accelerating electric charges.

Question 9

A light wave in air has a frequency of $$6 	imes 10$$^{14}$$ \ \mathrm{Hz}. $$What is its wavelength?

Accepted Answer

$$\lambda = \dfrac{c}{f} = \dfrac{3 	imes 10^8$}{6 	imes 10$$^{14}$$} = 5 	imes 10$$^{-7}$$ \ \mathrm{m}$$

Question 10

A beam of light passes from air ($$n=1.00) $$into glass ($$n=1.50) at an $$angle of $$30^\circ to $$the normal. What is the angle of refraction in the glass?

Accepted Answer

$$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2$$ \Rightarrow \sin \$$theta_2$$ = \dfrac{1.00 \sin 30^\circ}{1.50} = \dfrac{0.5}{1.5} = 0.333 \Rightarrow \$$theta_2 = 19.5$$^\circ$$

Question 11

A thin film of oil ($$n=1.40) $$floats on water ($$n=1.33). $$What is the minimum thickness of the oil film that will produce constructive interference for light of wavelength $$560 \ \mathrm{nm} in $$air, assuming normal incidence?

Accepted Answer

$$2nt = m\lambda \Rightarrow t = \dfrac{\lambda}{2n} = \dfrac{560}{2 	imes 1.40} = 200 \ \mathrm{nm}$$

Question 12

According to the photoelectric effect, what happens when light of frequency below the cutoff frequency shines on a metal surface?

Accepted Answer

No electrons are emitted, regardless of the light's intensity.

Question 13

What is the de Broglie wavelength of an electron moving at $$2 	imes 10^6$ \ \mathrm{m/s}$$? (Electron mass $$m = 9.11 	imes 10$$^{-31}$$ \ \mathrm{kg})$$

Accepted Answer

$$\lambda = \dfrac{h}{mv} = \dfrac{6.63 	imes 10$$^{-34}$$}{9.11 	imes 10$$^{-31}$$ 	imes 2 	imes 10^6$} = 3.64 	imes 10$$^{-10}$$ \ \mathrm{m}$$

Question 14

Which quantum number determines the shape of an electron's orbital in the hydrogen atom?

Accepted Answer

The azimuthal quantum number $$l$$

Question 15

A radioactive sample has a decay constant $$\lambda = 0.01 \ \mathrm{day}^{-1}. $$What is its half-life?

Accepted Answer

$$t_{1/2} = \dfrac{\ln 2}{\lambda} = \dfrac{0.693}{0.01} = 69.3 \ \mathrm{days}$$

Question 16

Which type of radiation has the greatest penetrating ability through matter?

Accepted Answer

Gamma rays

Question 17

A $$10 \ \mathrm{W}$$ light bulb operates at $$120 \ \mathrm{V}. $$What is the current through the bulb?

Accepted Answer

$$I = \dfrac{P}{V} = \dfrac{10}{120} = 0.083 \ \mathrm{A}$$

Question 18

Which of the following best describes nuclear fusion?

Accepted Answer

Two light nuclei combine to form a heavier nucleus, releasing energy.

Question 19

A hydrogen atom transitions from $$n=3 to$$ $$n=2. $$What is the energy of the photon emitted? (Use $$E_n = -13.6 \ \mathrm{eV}/n^2$)

Accepted Answer

$$E = E_2$ - E_3$ = \left(-3.4\right) - \left(-1.51\right) = 1.89 \ \mathrm{eV}$$

Physics Study Guide: Electricity, Magnetism, Waves, Quantum, Atomic, and Nuclear Physics

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