Lesson 5

Question 1

Power

Answer 1

Rate of energy flow in watts

1 watt = 1 joule/s

Question 2

Which colours are directly detected by cells in our eyes (primary colours of vision)?

Answer 2

Red
Blue
Green

Question 3

Four basic ways light interacts

Answer 3

• Emission (light comes from electric potential energy)
• Absorption
• Transmission
• Reflection/scattering

Question 4

Basic properties of waves

Answer 4

• Wavelength; distance between peaks or troughs
• Frequency; number of peaks passing each second (Hz)
• Speed; how fast energy travels from one place to another

Wavelength x Frequency = speed

Question 5

Light is an ____

Answer 5

electromagnetic wave
(electrons move when light passes by)

Question 6

What is the speed of light?

Answer 6

C = 300,000 km/s

Question 7

Relationship between wavelength and frequency

Answer 7

longer the wavelength = lower frequency and vice versa

Question 8

Photons

Answer 8

individual particle of light

- characterized by wavelength and frequency

Question 9

Relationship between wavelength and energy of photon

Answer 9

Shorter the wavelength (or high it’s frequency) = higher energy of photon

Question 10

Electromagnetic spectrum

Answer 10

complete spectrum of light

From highest energy/shortest wavelength/lowest frequency:
Gamma rays, X rays, Ultraviolet, Visible, Infrared, Radio waves, microwaves

Question 11

Visible light

Answer 11

400-700 nm

Blue (short wavelength = high frequency = high energy) - Red (long wavelength = low frequency = low energy)

Question 12

Atomic number

Answer 12

number of protons

Question 13

Atomic mass

Answer 13

protons + neutrons

Question 14

Isotopes

Answer 14

same #protons but different neutrons

Ex: Carbon 12 is 6 and 6, Carbon 13 has 7 neutrons, Carbon 14 has 8

Question 15

Plasma

Answer 15

hot gas which atoms have become ionized (stripped of electrons)

Question 16

Pressure

Answer 16

force per unit area pushing on an object’s surface

Question 17

Atoms contain energy in three ways:

Answer 17

• Mass energy (E=mc^2)
• Electrical potential energy (depends on arrangement of electrons around nuclei)
• Kinetic energy (motion)

Question 18

Electron’s energy levels

Answer 18

Electrons can only have particular amounts of energy

• Energy levels
• Ground state = O eV
• Excited states go higher levels depending on the atom
• Cannot be between levels; if has enough energy to get them halfway to the next level, will only go to the next possible level
• Ionization level = electron exits atom

Question 19

Spectroscopy

Answer 19

process of obtaining spectrum and reading information

Question 20

Continuous spectrum

Answer 20

broad range of wavelengths without interruptions

Question 21

Emission line spectrum

Answer 21

Emission lines against a black background

Emission lines depend on low-density cloud of gas composition and temperature

Question 22

Absorption line spectrum

Answer 22

dark absorption lines against rainbow background
Cloud of gas lying between us and light bulb (and cloud cooler than bulb or light source); we can’t see what the cloud absorbed