Waves
The distance from crest to crest in a wave (or trough to trough)
(What is) Wavelength
As an ambulance is driving away from you, what happens to the frequency (pitch) of the sound?
It goes down (gets lower)
What is the longest type of wave?
Radio waves
Device used to measure the average kinetic energy of a substance's molecules
A thermometer
Sound is carried by air molecules traveling from a source to a receiver through longitudinal waves. True or False?
False!
The air molecules do not travel, it is the wave that travels.
These waves do not need a medium to travel through
Electromagnetic waves (light)
Your bus drives by you at 30 m/s while honking its horn at 870 hertz. You're standing still as you watch it go by.
What is the velocity of the receiver?
0 m/s
What is the type of wave that is responsible for tanning your skin at the beach?
Ultra Violet (UV)
In what direction does heat flow?
From warm objects to cold objects.
How many nodes are in the wave I'm about to draw on the board?
4 nodes
Nodes are where the wave intersects with the mid-line.
The property of waves that tells us how many waves cycle through each second.
Bonus points for getting the Units!
Frequency (measured in hertz)
Your bus drives by you at 30 m/s while honking its horn at 870 hertz. You run towards the bus to try and catch up.
What is the velocity of the source?
30 m/s
What is the name of the range of the EM spectrum we can see?
Visible Light
Which one of these temperatures is the coldest:
a) 100K, b) 50 ° F, c) -10 ° C
K = ° C + 273
° C = 5/9(*°F - 32)
a) = -173° C
b) = 10° C
c) = -10° C
Crests and troughs are also known as:
Anti-nodes
What is the frequency of a blue light with wavelength 450 nanometers? (nanometer = 10^(-9) meters)
f = c/λ
6.67 * 10^14 Hz
Your bus drives past you at 30 m/s while honking its horn at 870 hertz. You're standing still as you watch it drive away.
Given that the speed of sound in the air is 340 m/s, what is the frequency that you hear?
F=Fo(V± Vr)/(V± Vs)
799.5 hertz or 800 Hz
Are EM waves an example of longitudinal, surface, or transverse waves?
Transverse
How much heat (thermal energy) do you need to heat 100g of soup with a heat capacity of 3 J/g °C by 25°C?
Q= m*c*ΔT
Q= 100g*3 J/g °C*25°C
= 7500 J
When we add two waves and the peaks are on the same side of the mid-line, we call this type of interference:
Constructive interference
What is the velocity of wave with wavelength 10 m and period 2s
v = λ *f
T = 1/f
5m/s
Your bus drives towards your bus stop at 30 m/s while honking its horn at 870 hertz. You're running towards your bus stop at 10 m/s.
Given that the speed of sound in the air is 340 m/s, what is the frequency that you hear?
F=Fo(V+-Vr)/(V+-Vs)
982.3 hertz
Find the velocity of a radio wave traveling through space with an unknown wavelength and an unknown frequency?
3*10^8 m/s
All EM waves travel at the speed of light!
What is the heat capacity of 500g of an unknown material? 10,000J of thermal energy (heat) is used to raise its temperature from 15°C to 28°C.
Don't forget units
Q=m*c*ΔT
c = Q/(m*ΔT)
= 1.54 J/g °C
Two pulses interfere: one has an amplitude of 2m the other has an amplitude of -4m. What is the amplitude of the resulting interference pattern.
Is this constructive or destructive interference?
Destructive interference: -2m