Q: Snell's law for refraction is given by which equation?

$$n_a \sin \theta_a = n_b \sin \theta_b$$

Q: The critical angle $$\theta_{\text{crit}}$$ for total internal reflection is given by:

$$\theta_{\text{crit}} = \sin$$^{-1}$$ \left( \frac{n_b}{n_a} \right)$$

Question 1

Which of the following correctly describes the relationship between the electric field $$\vec{E}$$ and magnetic field $$\vec{B} in a $$simple electromagnetic wave propagating in the $$x-$$direction?

Accepted Answer

$$\vec{E}$$ and $$\vec{B}$$ are perpendicular to each other and to the direction of propagation.

Question 2

What is the speed of light in vacuum, and which equation gives its value in terms of the permittivity $$\$$varepsilon_0$$ and permeability $$\$$mu_0 of $$free space?

Accepted Answer

$$c = \frac{1}{\sqrt{\$$varepsilon_0$$ \mu_0$}}$$ and $$c = 3.00 	imes 10^8$ m/s

Question 3

Which property is common to all electromagnetic waves?

Accepted Answer

They are transverse waves and do not require a medium for propagation.

Question 4

The ratio of the magnitudes of the electric and magnetic fields in an electromagnetic wave is given by:

Accepted Answer

$$\frac{E}{B} = c$$

Question 5

A sinusoidal electromagnetic wave has a wavelength $$\lambda$$ and frequency $$f. $$Which equation relates these quantities to the speed of light $$c$$?

Accepted Answer

$$c = f \lambda$$

Question 6

Which region of the electromagnetic spectrum has the shortest wavelength?

Accepted Answer

Gamma rays

Question 7

What is a wave front?

Accepted Answer

A surface on which the phase of a wave is the same.

Question 8

In geometric optics, what is the relationship between rays and wave fronts?

Accepted Answer

Rays are perpendicular to wave fronts.

Question 9

When light is reflected from a surface, which law describes the relationship between the angle of incidence $$	heta_i$$ and the angle of reflection $$	heta_r$$?

Accepted Answer

$$	heta_i = 	heta_r$$

Question 10

The refractive index $$n of a $$material is defined as:

Accepted Answer

$$n = \frac{c}{v}$$

Question 11

Snell's law for refraction is given by which equation?

Accepted Answer

$$n_a \sin 	heta_a = n_b \sin 	heta_b$$

Question 12

If a light ray passes from air ($$n=1) $$into glass ($$n=1.5) at an $$angle, what happens to the ray?

Accepted Answer

It bends toward the normal.

Question 13

Total internal reflection occurs when:

Accepted Answer

Light travels from a medium of higher refractive index to lower refractive index at an angle greater than the critical angle.

Question 14

The critical angle $$	heta_{	ext{crit}}$$ for total internal reflection is given by:

Accepted Answer

$$	heta_{	ext{crit}} = \sin$$^{-1}$$ \left( \frac{n_b}{n_a} ight)$$

Question 15

When light enters a material with refractive index $$n$$ from vacuum, which quantity changes?

Accepted Answer

The wavelength $$\lambda$$ decreases.

Question 16

Given $$v = f \lambda$$ and $$n = \frac{c}{v}$$, if the frequency of light in vacuum is $$f_0$$ and wavelength is $$\$$lambda_0$$, what is the wavelength $$\lambda$$ in a medium of refractive index n$?

Accepted Answer

$$\lambda = \frac{\$$lambda_0$$}{n}$$

Question 17

Which of the following sets of equations correctly describes the relationship between light frequency and wavelength in vacuum ($$f_0$$, $$\$$lambda_0$$) and in a material of refractive index n$ (f$, $$\lambda$$)?

Accepted Answer

$$f = f_0$, \lambda = \$$lambda_0$$ / n$$

Question 18

A student shines a laser beam from water ($$n=1.33) $$into air ($$n=1.00) at an $$angle greater than the critical angle. What happens to the beam?

Accepted Answer

It is totally internally reflected within the water.

Question 19

Which real-world application relies on total internal reflection?

Accepted Answer

Optical fibers for telecommunications

Electromagnetic Waves, Light, and Geometric Optics

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