Q: A 12 V car battery delivers a current of 60 A for 3 seconds when starting the engine. How much energy, in joules, does the battery supply during this time?

$$E = VIt = 12 \times 60 \times 3 = 2160\ \text{J}$$

Q: A wire carries a current of $$I = 5\ \text{A} in a $$uniform magnetic field of $$B = 0.2\ \text{T}$$, perpendicular to the wire. If the length of the wire in the field is $$L = 0.5\ \text{m}$$, what is the magnitude of the force on the wire?

$$F = BIL = 0.2 \times 5 \times 0.5 = 0.5\ \text{N}$$

Q: A transformer has 100 turns on its primary coil and 500 turns on its secondary coil. If the input voltage is $$120\ \text{V}$$, what is the output voltage (assuming 100% efficiency)?

$$V_s = V_p \frac{N_s}{N_p} = 120 \times \frac{500}{100} = 600\ \text{V}$$

Q: A double-slit experiment is performed with light of wavelength $$\lambda = 600\ \text{nm}$$ and slit separation $$d = 0.2\ \text{mm}. $$What is the angular position $$\theta of $$the first-order maximum?

$$d \sin \theta = m \lambda \Rightarrow \sin \theta = \frac{600 \times 10$$^{-9}$$}{0.2 \times 10$$^{-3}$$} = 3 \times 10$$^{-3}$$, $$\theta \approx 0.172^\circ$$

Question 1

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

Accepted Answer

The electric field describes the force per unit charge at a point, while electric potential describes the potential energy per unit charge at a point.

Question 2

A parallel-plate capacitor is connected to a battery and fully charged. If the plates are then pulled farther apart while the battery remains connected, what happens to the capacitance and the charge on the plates?

Accepted Answer

Question 3

A 12 V car battery delivers a current of 60 A for 3 seconds when starting the engine. How much energy, in joules, does the battery supply during this time?

Accepted Answer

$$E = VIt = 12 	imes 60 	imes 3 = 2160\ 	ext{J}$$

Question 4

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

Accepted Answer

Metals have loosely bound electrons that can move freely throughout the material.

Question 5

A wire carries a current of $$I = 5\ 	ext{A} in a $$uniform magnetic field of $$B = 0.2\ 	ext{T}$$, perpendicular to the wire. If the length of the wire in the field is $$L = 0.5\ 	ext{m}$$, what is the magnitude of the force on the wire?

Accepted Answer

$$F = BIL = 0.2 	imes 5 	imes 0.5 = 0.5\ 	ext{N}$$

Question 6

Which of the following is a correct statement of Faraday's Law of Electromagnetic Induction?

Accepted Answer

The induced emf in a closed loop is equal to the negative rate of change of magnetic flux through the loop.

Question 7

A transformer has 100 turns on its primary coil and 500 turns on its secondary coil. If the input voltage is $$120\ 	ext{V}$$, what is the output voltage (assuming 100% efficiency)?

Accepted Answer

$$V_s = V_p \frac{N_s}{N_p} = 120 	imes \frac{500}{100} = 600\ 	ext{V}$$

Question 8

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

Accepted Answer

$$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2$$ \Rightarrow \sin \$$theta_2$$ = \frac{$$n_1$$}{$$n_2$$} \sin \$$theta_1$$ = \frac{1.00}{1.50} \sin 30^\circ = \frac{1}{3}$$, \$$theta_2$$ \approx 19.5^\circ$

Question 9

Which of the following phenomena demonstrates the wave nature of light?

Accepted Answer

Interference and diffraction

Question 10

A double-slit experiment is performed with light of wavelength $$\lambda = 600\ 	ext{nm}$$ and slit separation $$d = 0.2\ 	ext{mm}. $$What is the angular position $$	heta of $$the first-order maximum?

Accepted Answer

$$d \sin 	heta = m \lambda \Rightarrow \sin 	heta = \frac{600 	imes 10$$^{-9}$$}{0.2 	imes 10$$^{-3}$$} = 3 	imes 10$$^{-3}$$, $$	heta \approx 0.172^\circ$$

Question 11

Which of the following best describes the function of a capacitor in an electrical circuit?

Accepted Answer

It stores electrical energy in the form of an electric field.

Question 12

A patient receives an MRI scan, which uses a strong magnetic field. Which force acts on the protons in the patient's body due to this field?

Accepted Answer

A magnetic force acts on moving protons, given by $$\vec{F} = q\vec{v} 	imes \vec{B}.$$

Question 13

Which of the following statements about electromagnetic waves is correct?

Accepted Answer

Electromagnetic waves can travel through a vacuum and do not require a medium.

Question 14

A resistor of $$10\ \Omega$$ and a capacitor of $$100\ \mu	ext{F}$$ are connected in series to a $$12\ 	ext{V}$$ battery. What is the time constant $$	au of $$the circuit?

Accepted Answer

$$	au = RC = 10 	imes 100 	imes 10$$^{-6}$$ = 0.001\ 	ext{s}$$

Question 15

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

Accepted Answer

Shorter wavelengths of light (blue) are scattered more than longer wavelengths by the atmosphere.

Question 16

A lens forms a real image of an object placed 30 cm from the lens. If the image is formed 60 cm on the other side of the lens, what is the focal length of the lens?

Accepted Answer

$$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} = \frac{1}{30} + \frac{1}{60} = \frac{3}{60} = \frac{1}{20} \Rightarrow f = 20\ 	ext{cm}$$

Question 17

Which of the following is NOT a property of electric field lines?

Accepted Answer

They form closed loops around isolated charges.

Question 18

A household circuit is protected by a 15 A fuse. If a toaster operates at 120 V and draws 10 A, what is the maximum power the toaster can safely use?

Accepted Answer

$$P = IV = 10 	imes 120 = 1200\ 	ext{W}$$

Question 19

Which of the following best describes the phenomenon of polarization of light?

Accepted Answer

The orientation of the oscillations of the electric field in a specific direction.

PHY 2054: Physics Without Calculus II – Electricity, Magnetism, and Optics (Syllabus & Course Guide)

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