Light

Question 1

What experiment demonstrates the wave nature of light?

Answer 1

Young’s double slit experiment

Question 2

Describe Young’s double slit experiment

Answer 2

• Single monochromatic light placed behind slit 1
• Light passes through slit and diffracts to hit Slit 2 and 3 creating two coherent wave sources
• These wave sources constructively and destructively interfere forming bright and dark fringes respectively.

Question 3

What is the modern version of Young’s slits

Answer 3

Diffraction grating

Question 4

How do you find the grating constant of a diffraction grating

Answer 4

d = 1/N , N = lines/m or d = 1x10^-3/N , N = lines/mm

Question 5

What happens when the # of lines per mm increases

Answer 5

Gaps between bright fringes increase

Question 6

What happens when the # of lines per mm decreases

Answer 6

Gaps between bright fringes decrease

Question 7

How do you calculate the wavelength of light using a diffraction grating

Answer 7

N lambda = dsin(theta)

Question 8

Derivation of formula for wavelength of light using diffraction grating

Answer 8

link

Question 9

What kind of wave is light

Answer 9

Transverse wave

Question 10

Can transverse waves be polarised

Answer 10

Yes

Question 11

Uses for polarization

Answer 11

Sunglasses, stress testing, reducing glare in windows

Question 12

What is dispersion

Answer 12

The separation of light into it’s constituent colors

Question 13

How do you disperse light

Answer 13

Using a prism/CD

Question 14

What are primary colors

Answer 14

The three main colors that combine to make white light (R,G,B)

Question 15

How are Secondary colors made

Answer 15

Combine two primary colors in equal amounts (R+B=Y)

Question 16

Complementary Colors

Answer 16

One primary and one secondary colour combine together to produce white light (B+Y=W)

Question 17

What happens to the energy of a wave as the wavelength gets smaller

Answer 17

Energy increases

Question 18

What happens to the energy of a wave as the wavelength gets longer

Answer 18

The energy decreases

Question 19

How fast does an EM wave travel

Answer 19

3x10^8 m/s

Question 20

What are other properties of EM waves

Answer 20

Can travel in a vacuum, display all phenomena of waves

Question 21

What kind of objects emit Infrared light

Answer 21

Hot objects

Question 22

What is infrared light useful for

Answer 22

Detecting objects in darkness or mist, remote control

Question 23

What produces UV light

Answer 23

Sun

Question 24

What are the results of over exposure to UV

Answer 24

Sunburn and can lead to cancer

Question 25

What properties does UV light have

Answer 25

Can’t pass through glass, causes fluorescence in some objects

Question 26

What are the parts of the Spectrometer

Answer 26

Heavy Base, Vernier Scale, Turntable and leveling screws, Collimator, Telescope

Question 27

What does the heavy Base do on the Spectrometer

Answer 27

Keeps the instrument in place, Vernier Scale is attached to it

Question 28

What is the turntable on the Spectrometer used for

Answer 28

Measures the angle of deviation

Question 29

What do the turntable and leveling screws do on the Spectrometer

Answer 29

It is the platform that the diffraction grating is set on and the leveling screws allow for the adjustment of the turntable and positions the grating

Question 30

What does the Collimator do on the Spectrometer

Answer 30

Consists of a slit through which light passes and a convex lens that focuses the light onto the grating, it collimates the light entering the Spectrometer

Question 31

What is the telescope used for on the Spectrometer

Answer 31

Used to view the fringes of light and can be rotated to find each order and the angle is read on the scale, consisting of two convex lenses