Module 1: Nature of Light

Question 1

Electromagnetic Spectrum

Answer 1

Continuous band of energy divided into 7 regions
Visible and UV used most in lab
In order of increasing wavelength:
gamma rays
X rays
Ultraviolet (180-380nm)
visible (380nm-780nm)
infrared
microwaves
radiowaves

Question 2

Electromagnetic radiation properties

Answer 2

1) travel in waves

2) Interacts with matter as particles

Question 3

Dual nature of light

Answer 3

Light is a massless particle that travels in a wave-like form
(both a particle and a wave)

Question 4

Photon

Answer 4

massless particle that contains a certain amount of energy

Question 5

Characteristics of Light waves

Answer 5

Wavelength
Amplitude
Frequency
Velocity

Question 6

Wavelength (λ)

Answer 6

Distance between 2 consecutive peaks in the wave pattern

Expressed in nanometers (nm)

Question 7

Amplitude (A)

Answer 7

Total wave height (from trough to peak) which relates to the intensity

Question 8

Frequency (f)

Answer 8

Number of wave cycles passing a given point per second

Question 9

Velocity (v or c)

Answer 9

Speed of light

Varies depending on the medium the light wave is traveling through

Question 10

Energy of a photon is determined by:

Answer 10

the wavelength (and frequency) of the light

Question 11

High energy photon

Answer 11

Light with a short wavelength and high frequency

Question 12

Low energy photon

Answer 12

Light with a long wavelength and low frequency

Question 13

White light

Answer 13

When all visible light wavelengths are present

Question 14

Polychromatic

Answer 14

Light consisting of all or a portion of the wavelengths of the spectrum

Question 15

Monochromatic

Answer 15

Light of one wavelength

Question 16

Manipulations of light (5)

Answer 16

Reflection
Refraction
Diffraction
Interference
Polarization

Question 17

Reflection

Answer 17

The change in direction of a wave of light due to interaction with a reflecting surface (mirror, water surface, shiny metals)

Question 18

Refraction

Answer 18

Bending of light rays
Change in medium density (from one medium to another) alters the velocity of the light
Shorter wavelengths are refracted more than longer wavelengths

Question 19

Diffraction

Answer 19

As light passes through a slit or narrow opening, it is bent by the edges of the slit

Question 20

Interference

Answer 20

Result of light waves interacting with each other

Question 21

Interference “in phase”

Answer 21

Light waves that are synchronized (peaks and troughs match)

Interfere constructively, reinforcing each other and increasing intensity

Question 22

Interference “out of phase”

Answer 22

Light waves that are not synchronized

Interfere destructively resulting in lower intensity or cancelling each other out

Question 23

Polarization

Answer 23

Passing unpolarized ray of light through special lens or crystal, only one plane of orientation may be selected

Question 24

Polarized light

Answer 24

Light that is orientated in only one plane

Question 25

Unpolarized light

Answer 25

Light that is orientated in multiple planes