Question 1

Which of the following statements best describes Maxwell’s unification of electricity and magnetism?

Accepted Answer

Maxwell unified electric and magnetic phenomena by showing that changing electric fields produce magnetic fields and vice versa.

Question 2

Which of Maxwell’s equations states that the net electric flux through a closed surface is proportional to the enclosed electric charge?

Accepted Answer

Gauss’ Law

Question 3

A parallel-plate capacitor is being charged. According to Maxwell’s correction to Ampère’s Law, what is the source of the magnetic field between the plates?

Accepted Answer

The changing electric field (displacement current) between the plates

Question 4

Which equation describes the relationship between the speed of light $$c$$, the permittivity of free space $$\$$varepsilon_0$$, and the permeability of free space $$\$$mu_0$$?

Accepted Answer

$$c = \frac{1}{\sqrt{\$$varepsilon_0$$ \mu_0$}}$$

Question 5

Which of the following best describes the direction of propagation of an electromagnetic wave?

Accepted Answer

Perpendicular to both the electric and magnetic fields

Question 6

A radio antenna emits electromagnetic waves. What is the primary mechanism by which these waves are generated?

Accepted Answer

Oscillating electric charges in the antenna

Question 7

Which Maxwell equation explains why the magnetic field lines always form closed loops and have no beginning or end?

Accepted Answer

Gauss’ Law for Magnetism

Question 8

If the electric field in an electromagnetic wave is described by $$E = E_0$ \sin(kx - \omega t)$$, what is the corresponding form of the magnetic field $$B$$?

Accepted Answer

$$B = B_0$ \sin(kx - \omega t)$$, perpendicular to E

Question 9

The Poynting vector $$\vec{S}$$ represents which physical quantity in electromagnetic waves?

Accepted Answer

The power per unit area carried by the wave

Question 10

A perfectly absorbing surface is exposed to an electromagnetic wave with intensity $$I. $$What is the radiation pressure $$P$$ exerted on the surface?

Accepted Answer

$$P = \frac{I}{c}$$

Question 11

Which of the following is NOT a consequence of Maxwell’s equations?

Accepted Answer

Magnetic monopoles exist

Question 12

A laser beam with power $$P is $$completely reflected by a mirror. What is the total force $$F$$ exerted on the mirror?

Accepted Answer

$$F = \frac{2P}{c}$$

Question 13

Which of the following best describes the energy density $$u of an $$electromagnetic wave in terms of the electric field $$E$$ and magnetic field $$B$$?

Accepted Answer

$$u = \frac{1}{2} \$$varepsilon_0$$ E^2$ + \frac{1}{2\mu_0$} B^2$

Question 14

A capacitor is being charged in an RC circuit. If the current in the wire is $$I$$, what is the displacement current $$I_d$$ between the plates?

Accepted Answer

$$I_d = I$$

Question 15

Which of the following is a correct statement about the electromagnetic spectrum?

Accepted Answer

Microwaves have longer wavelengths than ultraviolet light.

Question 16

If an electromagnetic wave has a frequency $$f$$ and wavelength $$\lambda$$, what is the relationship between these quantities and the speed of light $$c$$?

Accepted Answer

$$c = f \lambda$$

Question 17

Which of the following scenarios would NOT produce electromagnetic waves?

Accepted Answer

A stationary electric charge

Question 18

Which law explains the induction of an electric field by a changing magnetic field?

Accepted Answer

Faraday’s Law

Question 19

A solar sail is propelled by sunlight. If the intensity of sunlight is $$I$$ and the sail is perfectly reflective, what is the radiation pressure $$P on $$the sail?

Accepted Answer

$$P = \frac{2I}{c}$$

Maxwell’s Equations and Electromagnetic Waves

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