Q: A 2.0 kg object is dropped from a height of 10 m. Ignoring air resistance, what is its speed just before it hits the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

$$v = \sqrt{2gh} = \sqrt{2 \times 9.8 \times 10} = 14\ \mathrm{m/s}$$

Q: A wire carries a current of $$I = 2\ \mathrm{A} in a $$uniform magnetic field of $$B = 0.5\ \mathrm{T}. $$The wire is $$0.3\ \mathrm{m}$$ long and oriented perpendicular to the field. What is the magnitude of the force on the wire?

$$F = BIL = 0.5 \times 2 \times 0.3 = 0.3\ \mathrm{N}$$

Question 1

A patient receives a chest X-ray in a hospital. Which of the following best explains why X-rays are able to produce images of bones inside the body?

Accepted Answer

X-rays have higher energy and shorter wavelength than visible light, so they are absorbed more by dense materials like bone.

Question 2

A 2.0 kg object is dropped from a height of 10 m. Ignoring air resistance, what is its speed just before it hits the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v = \sqrt{2gh} = \sqrt{2 	imes 9.8 	imes 10} = 14\ \mathrm{m/s}$$

Question 3

Which of the following best describes the difference between electric potential and electric field?

Accepted Answer

Electric field is the rate of change of electric potential with respect to distance.

Question 4

A parallel-plate capacitor is connected to a battery and then disconnected. If the plates are pulled farther apart, what happens to the voltage across the plates?

Accepted Answer

The voltage increases because the capacitance decreases and charge remains constant.

Question 5

Which of the following is the correct expression for the energy stored in a capacitor with capacitance $$C$$ and voltage $$V$$?

Accepted Answer

$$E = \frac{1}{2}CV^2$

Question 6

A wire carries a current of $$I = 2\ \mathrm{A} in a $$uniform magnetic field of $$B = 0.5\ \mathrm{T}. $$The wire is $$0.3\ \mathrm{m}$$ long and oriented perpendicular to the field. What is the magnitude of the force on the wire?

Accepted Answer

$$F = BIL = 0.5 	imes 2 	imes 0.3 = 0.3\ \mathrm{N}$$

Question 7

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have free electrons that can move easily throughout the lattice.

Question 8

A circuit contains a $$12\ \mathrm{V}$$ battery and two resistors, $$R_1 = 4$$\ \Omega$$ and R_2$ = 8\ \Omega$$, connected in series. What is the current in the circuit?

Accepted Answer

$$I = \frac{V}{R_1$ + R_2$} = \frac{12}{4+8} = 1\ \mathrm{A}$$

Question 9

Which of the following statements about electromagnetic waves is correct?

Accepted Answer

Electromagnetic waves can travel through a vacuum and consist of oscillating electric and magnetic fields.

Question 10

A ray of light passes from air ($$n_1 = 1.00$) into water (n_2$ = 1.33) at an $$angle of $$30^\circ to $$the normal. What is the angle of refraction in the water? (Use Snell's Law: $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2)$$

Accepted Answer

$$\$$theta_2$$ = \arcsin\left(\frac{n_1$}{n_2$} \sin \$$theta_1$$ight) = \arcsin\left(\frac{1.00}{1.33} 	imes \sin 30^\circight) = 22^\circ$$

Question 11

Which of the following best describes the photoelectric effect?

Accepted Answer

Electrons are emitted from a metal surface when it is exposed to light of sufficient frequency.

Question 12

A radioactive isotope has a half-life of 5 years. If you start with 80 grams, how much remains after 15 years?

Accepted Answer

10 grams

Question 13

Which of the following is the correct relationship for the speed of light $$c$$, frequency $$f$$, and wavelength $$\lambda of an $$electromagnetic wave?

Accepted Answer

$$c = f \lambda$$

Question 14

A patient is treated with a radioactive isotope for cancer therapy. Which type of radiation is most likely to cause ionization in biological tissue?

Accepted Answer

Gamma rays

Question 15

A 60 W light bulb is connected to a 120 V outlet. What is the current through the bulb?

Accepted Answer

$$I = \frac{P}{V} = \frac{60}{120} = 0.5\ \mathrm{A}$$

Question 16

Which of the following best explains why the sky appears blue during the day?

Accepted Answer

Blue light is scattered more than red light by the atmosphere due to its shorter wavelength.

Question 17

A patient receives a dose of 0.5 Gy of ionizing radiation. Which of the following best describes the meaning of 1 Gray (Gy)?

Accepted Answer

1 Gy is the absorption of 1 joule of radiation energy per kilogram of tissue.

Question 18

A proton moves perpendicular to a uniform magnetic field. Which of the following best describes its motion?

Accepted Answer

It moves in a circular path at constant speed.

Question 19

Which of the following is a correct statement about the relationship between energy, frequency, and wavelength for a photon?

Accepted Answer

$$E = hf$$ and $$\lambda = \frac{c}{f}$$

Physics 1021: Syllabus and Study Guide – Principles with Applications

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