Q: A diffraction grating has 5000 lines per centimeter. What is the slit spacing $$d in $$meters?

$$2.0 \times 10$$^{-6}$$\ \mathrm{m}$$

Q: Which of the following equations gives the condition for the minima (dark fringes) in a single-slit diffraction pattern?

$$a \sin \theta = p \lambda$$\ for\ p = 1, 2, 3, ...$

Q: Which of the following statements about the central maximum in a single-slit diffraction pattern is correct?

It is located at $$\theta = 0$$ and has the highest intensity.

Q: Which of the following best explains why the central maximum in a single-slit diffraction pattern is much brighter than the other maxima?

All the wavelets from the slit add constructively at $$\theta = 0.$$

Question 1

Which of the following best describes why the speed of light decreases when it passes from air into glass?

Accepted Answer

Because the electromagnetic wave interacts with electrons in the material, causing the speed to decrease.

Question 2

A beam of orange light with a wavelength of $$600\ \mathrm{nm} in $$air enters a glass slide with $$n = 1.50. $$What is the wavelength of the light inside the glass?

Accepted Answer

$$400\ \mathrm{nm}$$

Question 3

The index of refraction $$n is $$defined as:

Accepted Answer

$$n = \dfrac{c}{v}$$,\ where\ c\ is\ the\ speed\ of\ light\ in\ vacuum\ and\ v\ is\ the\ speed\ in\ the\ material$

Question 4

In Young’s double-slit experiment, constructive interference (bright fringes) occurs at points where the path difference between the two slits is:

Accepted Answer

A whole number of wavelengths: $$\Delta r = m\lambda$$

Question 5

A double-slit experiment uses light of wavelength $$500\ \mathrm{nm}$$, slit separation $$0.5\ \mathrm{mm}$$, and a screen $$2.0\ \mathrm{m}$$ away. What is the distance between adjacent bright fringes on the screen?

Accepted Answer

$$2.0\ \mathrm{mm}$$\ (using\ \Delta y = \dfrac{\lambda L}{d} = \dfrac{500 	imes $$10^{-9}$$ 	imes 2.0}{0.5 	imes $$10^{-3}$$} = 2.0 	imes $$10^{-3}$$\ \mathrm{m} = 2.0\ \mathrm{mm}$)

Question 6

If the screen in a double-slit experiment is moved farther from the slits, what happens to the spacing between the bright fringes?

Accepted Answer

The fringes get farther apart.

Question 7

If the wavelength of light used in a double-slit experiment is increased, what happens to the fringe spacing?

Accepted Answer

The fringes get farther apart.

Question 8

A diffraction grating has 5000 lines per centimeter. What is the slit spacing $$d in $$meters?

Accepted Answer

$$2.0 	imes 10$$^{-6}$$\ \mathrm{m}$$

Question 9

A student shines a $$530\ \mathrm{nm}$$ green laser on a single hair and observes a central maximum width of $$14\ \mathrm{mm} on a $$screen $$1.2\ \mathrm{m}$$ away. What is the thickness of the hair?

Accepted Answer

$$91\ \mu\mathrm{m}$$

Question 10

In a single-slit diffraction experiment, if the slit is made narrower, what happens to the width of the central maximum?

Accepted Answer

It becomes wider.

Question 11

Which of the following equations gives the condition for the minima (dark fringes) in a single-slit diffraction pattern?

Accepted Answer

$$a \sin 	heta = p \lambda$$\ for\ p = 1, 2, 3, ...$

Question 12

A feather produces a rainbow pattern when illuminated by white light. This is best explained by:

Accepted Answer

Diffraction and interference from the evenly spaced barbules acting as a grating.

Question 13

Which of the following statements about the central maximum in a single-slit diffraction pattern is correct?

Accepted Answer

It is located at $$	heta = 0$$ and has the highest intensity.

Question 14

In a double-slit experiment, if the slit separation $$d is $$decreased, what happens to the fringe spacing?

Accepted Answer

The fringes get farther apart.

Question 15

Which principle states that the diffraction pattern from an opaque body is the same as that from a hole or slit of the same size?

Accepted Answer

Babinet’s Principle

Question 16

A diffraction grating produces sharp, bright maxima because:

Accepted Answer

Many slits reinforce the constructive interference at specific angles.

Question 17

If a green laser ($$\lambda = 530\ \mathrm{nm}) is $$replaced with a red laser ($$\lambda = 650\ \mathrm{nm}) in a $$single-slit diffraction experiment, what happens to the width of the central maximum?

Accepted Answer

It becomes wider.

Question 18

Which of the following best explains why the central maximum in a single-slit diffraction pattern is much brighter than the other maxima?

Accepted Answer

All the wavelets from the slit add constructively at $$	heta = 0.$$

Question 19

A double-slit experiment is performed with a screen $$L$$ meters away, slit separation $$d$$, and light of wavelength $$\lambda. $$The position $$y_m of $$the $$mth $$bright fringe is given by:

Accepted Answer

$$y_m = m \dfrac{\lambda L}{d}$$

Chapter 17: Wave Optics – Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards