Module 3 : Waves Flashcards Preview

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(Waves Part 1 : Basic Characteristics of Waves)
Explain the difference between a transverse wave and a longitudinal wave, and give examples of each

- Transverse wave : moves up and down, perpendicular (examples : water waves, electromagnetic waves, and light waves)
- Longitudinal wave : moves from left to right, parallel to one another (example : sound waves, tuning fork, earthquake seismic waves)

1

(Waves Part 1 : Basic Characteristics of Waves)
What is a wave?

- a disturbance that travels through space and time accompanied by the transfer of energy
- it is a vibration, a vibration is a wiggle, and a wiggle that travels is called a wave
- carry energy from one place to another

2

(Waves Part 1 : Basic Characteristics of Waves)
Describe the following terms associated with waves :
(A) wavelength
(B) frequency
(C) amplitude

(A) wavelength :
- property of a wave that is the distance between identical points in between two successive waves
- the distance between one crest (or trough) of one wave and the next is considered wavelength
(B) frequency (often measured in hertz Hz) :
- the number of to and fro vibrations made in a given time (usually one second)
- how many waves pass by per unit of time
(C) amplitude :
- same thing as height
- measurement of wave from the center, or equilibrium point to the highest point (top of peak)
- in astronomy, it tells you about the intensity of something

3

(Waves Part 1 : Basic Characteristics of Waves)
amplitude

- the maximum displacement on either side of the equilibrium (midpoint) position

4

(Waves Part 1 : Basic Characteristics of Waves)
frequency

- the number of vibrations per unit time
- for a wave, the number of crests that pass a particular point per unit time

5

(Waves Part 1 : Basic Characteristics of Waves)
period

- time required for a vibration or a wave to make a complete cycle, equal to 1/frequency

6

(Waves Part 1 : Basic Characteristics of Waves)
wavelength

- the distance between successive crests, troughs, or identical parts of a wave

7

(Waves Part 2 : Reflection Refraction, Diffraction, and Interference)
Explain reflection, refraction, and diffraction of waves.

- reflection : the returning of a wave to the medium from which it came when it hits a barrier
- refraction : the path of a wave bends due to moving from one medium to another
- diffraction : spreading of two or more waves with each other

8

(Waves Part 2 : Reflection Refraction, Diffraction, and Interference)
What is interference? How do constructive and destructive interference differ?

- interference : the interaction of two or more waves with each other
- constructive interference : when two identical waves overlap each other at the crest, result is wave with increased amplitude (example : in a concert hall, hearing two speakers and getting a "loud" spot)
- destructive interference : when crest of one wave and trough of another wave overlap, effect is reduced, high part fills in low part and they cancel each other out (example : noise cancelling headphones)

9

(Waves Part 3 : The Doppler Effect)
What is the Doppler effect?

- the change in frequency of a wave due to the motion of the source (or due to the motion of the receiver)
- blue shift : light moving towards you, shorter frequency
- red shift : light moving away from you, longer frequency

10

(Waves Part 3 : The Doppler Effect)
A train travels towards you, emitting a horn at a frequency of 256 Hz. Due to the Doppler Effect, the frequency of sound that you hear is actually :
(A) higher than 256 Hz
(B) lower than 256 Hz
(C) equal to 256 Hz

ANSWER
(A) higher than 256 Hz

11

(Waves Part 4 : Sound vs Light)
What changes the pitch of sound?

- the speed of vibrations
- low pitch = low frequency = lower vibrations
- high pitch = high frequency = higher vibrations

12

(Waves Part 4 : Sound vs. Light)
Sound travels fastest in :
(A) air
(B) water
(C) steel
(D) a vacuum (nothing at all)

ANSWER
(A) steel

13

(Waves Part 4 : Sound vs. Light)
Light requires a medium to move through.
True or false?

ANSWER
false

14

(Waves Part 4 : Sound vs. Light)
Which of the following is NOT a transverse wave?
(A) sound
(B) light
(C) water
(D) "the wave" at a stadium

ANSWER
(A) sound

15

(Electromagnetic Spectrum)
What is an electromagnetic wave?

- also known as light
- accelerating electric charge : creates an oscillating electromagnetic field
- transverse waves
- requires no medium
- all travel at the same speed 300,000,000 m/s

16

(Electromagnetic Spectrum)
List the types of electromagnetic waves that are located on the electromagnetic spectrum in order from highest frequency to lowest frequency.

(A) gamma rays : used to treat; diagnose cancer (highest energy wave, tiny short waves, high frequency - emits red light)
(B) x-rays : used to detect broken bones; detects cavities in teeth
(C) ultraviolet rays : are used to sanitize because they have the ability to kill bacteria; whitens teeth
(D) visible light : middle of the electromagnetic spectrum - this is what we see as visible light
(E) infrared : thermal imaging; detects heat
(F) microwaves : used to heat food
(G) radio waves : wireless internet; cell phones (longest wavelength, low frequency, low energy. Used in communications)


17

(Electromagnetic Spectrum)
How are electromagnetic waves the same? How do they differ?

- same : they all travel at the same speed
- different : some we can see and others we can't (we can only see the ones beyond visible light, but not the ones before it), they also differ in intensity and wavelength

18

(Electromagnetic Spectrum)
Describes common practical applications for each of the different types of electromagnetic waves.

- radio applications : very common with Intel communications, RFID tags inside clothes that make store alarms go off
- microwave applications : cooking with microwave oven
- infrared applications : observes heat
- ultraviolet applications : sterilization of food and medical equipment
- X-ray : imaging for medical/security applications
- gamma rays : cancer treatment

19

(Electromagnetic Spectrum)
Compare the wavelengths, frequencies, and energy of the different types of electromagnetic waves, including the different colors of visible light

(A) gamma rays :
- wavelength : less than 10 pico meters (10^-11 meter), less than the diameter of an atom
- frequency : above 10 exahertz (or 10^19 Hz)
- energy : 10^6 electron volts
- colors of visible light : no visible light
(B) x-rays :
- wavelength : 0.01 to 10 nanometers
- frequency : 30 petahertz to 30 exahertz (3x10^16 Hz to 3x10^19 Hz)
- energy : 100 eV (electron volts) to 100 keV (kilo electron volts)
- colors of visible light : little to none, violet
(C) ultraviolet rays :
- wavelength : about 400 to 4 nanometers
- frequency : about 10^15 to 10^17 Hz
- energy : about 10^2 eV
- colors of visible light : not much, purple
(D) visible light :
- wavelength : 380 nanometers to 750 nanometers
- frequency : 400 to 790 THz
- energy : 2-3 eV
- colors of visible light : violet, indigo, blue, green, yellow, orange, red
(E) infrared :
- wavelength : 700 nanometers to 1 mm
- frequency : 430 THz to 300 GHz
- energy : 0.01-2 eV
- colors of visible light : red to violet
(F) microwaves :
- wavelength : 1 meter to 1 milliliter
- frequency : 300 MHz and 300 GHz
- energy : 10^-5 to 0.01 eV
- colors of visible light : red to indigo
(G) radio waves :
- wavelength : longer than infrared as long as q 1 milliliter to 100 kilometers
- frequency : 300 GHz to as low as 3 kHz
- energy : less than 10^-5 eV
- colors of visible light : no color

20

(Electromagnetic Spectrum)
What methods can you use to remember the order of the types of waves on the electromagnetic spectrum? How can you remember which are on the high energy/high frequency/short wavelength end and which are on the low energy/low frequency/ long wavelength end?

- help to remember :
- highest to lowest frequency Good Xylophones Use Very Interesting Musical Rhythm
- lowest to highest frequency Real Men In Vegas Use X-Ray Goggles
- colors in visible spectrum : Roy g biv (red, orange, yellow, green, blue, indigo, violet)

21

(Electromagnetic Spectrum)
Which of the following is most unlike the others?
(A) radio waves
(B) gamma rays
(C) sound waves
(D) microwaves

ANSWER
(D) sound waves

22

(Electromagnetic Spectrum)
Which type of electromagnetic radiation possesses the most energy?
(A) radio waves
(B) gamma rays
(C) visible light
(D) microwaves
(E) X-rays

ANSWER
(B) gamma rays

23

(Electromagnetic Spectrum)
Which type of electromagnetic radiation possesses the longest wavelength?
(A) radio waves
(B) gamma rays
(C) visible light
(D) microwaves
(E) X-rays

ANSWER
(A) radio waves

24

(Electromagnetic Spectrum)
Which type of electromagnetic radiation is utilized in night-vision goggles?
(A) infrared light
(B) gamma rays
(C) visible light
(D) microwaves
(E) X-rays

ANSWER
(A) infrared light

25

(Electromagnetic Spectrum)
Which type of electromagnetic radiation it utilized in transmitting cell phone calls?
(A) infrared light
(B) gamma rays
(C) visible light
(D) radio waves
(E) X-rays

ANSWER
(D) radio waves

26

(Electromagnetic Spectrum)
Which type of electromagnetic radiation is utilized in radiation therapy for cancer?
(A) infrared light
(B) gamma rays
(C) visible light
(D) radio waves
(E) X-rays

ANSWER
(B) gamma rays

27

Quiz A
What statement correctly describes the movement of seismic waves?

- Primary waves are longitudinal waves that travel with the greatest speed
- Primary waves (P-waves) and secondary waves are types of seismic body waves. Primary waves are longitudinal waves that move the fastest. Secondary waves (S-waves) are transverse waves that only move through solids and are slower than primary waves

28

Quiz A
What correctly describes wave motion?

- Longitudinal waves consist of compressions and rarefactions moving parallel to the wave motion.
- Transverse waves are vibrations that move at fight angles to wave movement in an up and down motion. Longitudinal waves are vibrations that move parallel to the wave movement and consist of compressions and rarefactions.

29

Quiz A
How are light waves different than sound waves?

- Light waves result from the acceleration of electrons whereas sound waves result when disturbances cause the movement of molecules.
- Light waves are transverse, electromagnetic waves that do not require a medium to move. Sound waves are longitudinal waves that require a medium (solid, liquid, or gas) to move