Unit 4: Light & Observations

Question 1

What is wavelength?

Answer 1

The distance between wave crests of dips

Question 2

What is frequency?

Answer 2

How many crests pass per time (unit of Hertz = 1/s)

Question 3

What is the doppler shift?

Answer 3

A general property of waves (both sound and light) and the wavefronts emitted by a moving source are spaced more closely than in the direction of motion

Question 4

What properties do sound waves have when a source is moving toward or away from the observers?

Answer 4

-Towards: A higher frequency
-Away: A lower frequency

Question 5

What properties do light waves have when a source is moving toward or away from the observers?

Answer 5

-Towards: Appears bluer and has a shorter wavelength
-Away: Appears redder and has a longer wavelength

Question 6

List the wavelengths from lowest frequency to highest frequency: Microwave, infrared, gamma ray, x-ray, radio, ultraviolet, visible

Answer 6

Radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray

Question 7

What is the blackbody spectrum?

Answer 7

Energy radiated by any object or system that absorbs all radiation
(Hotter objects emit more light and at a higher frequency on average)
(ex: light bulb)

Question 8

What is the absorption line spectrum?

Answer 8

Atoms in a gas cloud absorb light of certain specific wavelength, producing dark lines in the spectrum

Question 9

What is the continuous spectrum?

Answer 9

A spectrum where blackbody emits light at all wavelengths

Question 10

What are atomic lines and what are they used to determine?

Answer 10

They are lines in a spectrum in which light of only a certain wavelength is emitted or absorbed but not continuous, and it’s used to determine the composition of material (stars, gas, clouds, planets)