test review waves, optics, modern physics. characteristics of waves one thing all waves have in...

Test Review

Waves, Optics, Modern Physics

Characteristics of Waves

• One thing ALL waves have in common is that they all transfer energy.

• As they travel through a medium, they move the molecules around, but eventually leave them in the same place they started.

Characteristics of Waves

• Consider the following wave: Frequency = 10 Hz

20 m

4 m

Characteristics of Waves

• What is it’s amplitude? Frequency = 10 Hz

20 m

4 m

Characteristics of Waves

• What is it’s amplitude? Frequency = 10 Hz

20 m

4 m

Characteristics of Waves

• What is it’s amplitude? Frequency = 10 Hz

20 m

4 m

10 m

Characteristics of Waves• What is it’s wavelength (λ)?

Frequency = 10 Hz

20 m

4 m

Characteristics of Waves• What is it’s wavelength (λ)?

Frequency = 10 Hz

20 m

4 m

Characteristics of Waves• What is it’s wavelength (λ)?

Frequency = 10 Hz

20 m

4 m

8 m

Characteristics of Waves

• What is it’s period? Frequency = 10 Hz

20 m

4 m

Characteristics of Waves

• What is it’s period? Frequency = 10 Hz

20 m

4 m

Period = 1/f

Characteristics of Waves

• What is it’s period? Frequency = 10 Hz

20 m

4 m

Period = 1/f

sec1.010

1

Hz

T

Characteristics of Waves

• What is it’s velocity? Frequency = 10 Hz

20 m

4 m

Characteristics of Waves

• What is it’s velocity? Frequency = 10 Hz

20 m

4 m

fv

Characteristics of Waves

• What is it’s velocity? Frequency = 10 Hz

20 m

4 m

fv

smv

mHzv

/80

)8)(10(

Characteristics of Waves

• Example: A radio wave has a frequency of 104 kHz. What is its wavelength?

Characteristics of Waves

• Example: A radio wave has a frequency of 104 kHz. What is its wavelength?

Fact: Radio waves travel at the speed of light, so we know that v=3.0E8m/s for the radio wave.

Characteristics of Waves

• Example: A radio wave has a frequency of 104 kHz. What is its wavelength?v=3.0E8m/s f= 104kHz= 104,000Hz

Characteristics of Waves

• Example: A radio wave has a frequency of 104 kHz. What is its wavelength?v=3.0E8m/s f= 104kHz= 104,000Hz

fv

Characteristics of Waves

• Example: A radio wave has a frequency of 104 kHz. What is its wavelength?v=3.0E8m/s f= 104kHz= 104,000Hz

fv

m

E

HzsmE

6.2884

000,104

80.3

)000,104(/80.3

Characteristics of Waves

• Frequency vs. Period.

• Frequency is the inverse of Period so it means that the graph looks like this:

Period

Freq

uenc

y

Characteristics of Waves

• An singer can break glass if they sing a note that has the same what as the glass?

Characteristics of Waves

• An singer can break glass if they sing a note that has the same what as the glass?

Natural Frequency

Types of Waves

• What kind of wave is each: Transverse or compressional?

Light ??

Sound ??

Types of Waves

• What kind of wave is each: Transverse or compressional?

Light Transverse

Sound Compressional

The Doppler Effect

• Which side will hear a lower pitch and which side a higher pitch?

The Doppler Effect

LOWER PITCH HIGHER PITCH

Wave Interference

• What will the resultant amplitude be as these two waves overlap?

2x x

Wave Interference

• What will the resultant amplitude be as these two waves overlap?

3x

Test Review

•Optics

The Lens/Mirror Formula

• This formula works for ALL mirrors and lenses.• It doesn’t matter if they are concave or

convex.

f

Real Pencil

Pencil’s Reflection

p

q

The Lens/Mirror Formula

• This formula works for ALL mirrors and lenses.• It doesn’t matter if they are concave or

convex.

f

Real Pencil

Pencil’s Reflection

p

q

fqp

111

The Lens/Mirror Formula

• An object is placed 50 cm in front of a mirror with a focal length of 30 cm. What is the image distance from the mirror?

The Lens/Mirror Formula

• An object is placed 50 cm in front of a mirror with a focal length of 30 cm. What is the image distance from the mirror?p= 50cm f= 30cm q=?

The Lens/Mirror Formula

• An object is placed 50 cm in front of a mirror with a focal length of 30 cm. What is the image distance from the mirror?p= 50cm f= 30cm q=?

cmcmq

cmqcm

fqp

50

1

30

11

30

11

50

1

111

qcm

q

q

0.75

013.01

013.01

The Lens/Mirror Formula

• Find the magnification of the same mirror.

The Lens/Mirror Formula

• Find the magnification of the same mirror.

We can find magnification by p

q

The Lens/Mirror Formula

• Find the magnification of the same mirror.p= 50cm q= 75cm

Magnification equals

5.150

75

cm

cm

p

q

Snell’s Law

• The Index of Refraction (n) tells us how fast light travels through a medium.

• As n gets lower, light travels faster. Light travels fastest in a vacuum.

Snell’s Law

• Example: A beam of light travels from crystal into water with an angle of incidence of 60° and an angle of refraction of 50°. Find the index of refraction of the crystal. (nwater=1.33)

Snell’s Law

• Example: A beam of light travels from crystal into water with an angle of incidence of 60° and an angle of refraction of 50°. Find the index of refraction of the crystal. (nwater=1.33)

Snell’s Law: n1sinθ1= n2sinθ2

.

Snell’s Law

• Example: A beam of light travels from crystal into water with an angle of incidence of 60° and an angle of refraction of 50°. Find the index of refraction of the crystal. (nwater=1.33)

Snell’s Law: n1sinθ1= n2sinθ2

18.187.

01.1

01.187.0

50sin33.160sin

1

1

1

n

n

n

Modern Physics

Half Life

• Over time radioactive stuff looses it’s mass because of radiation.

• A Half Life is the amount of time it takes for half of a sample to disappear.

• i.e.- If 1kg of stuff has a half life of 10min. After 10min, there is only 0.5kg left.

Half Life

• If a 10kg sample of a radioactive substance has a half life of 5 sec, how much will be left after 15 sec?

Half Life

• If a 10kg sample of a radioactive substance has a half life of 5 sec, how much will be left after 15 sec?

-How many half lives go past in 15 sec?

Half Life

• If a 10kg sample of a radioactive substance has a half life of 5 sec, how much will be left after 15 sec?

-How many half lives go past in 15 sec? 3

Half Life

• If a 10kg sample of a radioactive substance has a half life of 5 sec, how much will be left after 15 sec?

-How many half lives go past in 15 sec? 3

So… divide 10kg by 2 three times…

Half Life

• If a 10kg sample of a radioactive substance has a half life of 5 sec, how much will be left after 15 sec?

-How many half lives go past in 15 sec? 3

So… divide 10kg by 2 three times…

kgkg 25.122210

Atomic Energy

• Nuclear reactions can transfer matter into energy.

• One type of reaction is Fusion.

Atomic Energy

• Nuclear reactions can transfer matter into energy.

• One type of reaction is Fusion.

• An example of fusion would be two Hydrogen atoms colliding and turning into a Helium atom and releasing energy. In the sun.

HeHH 42

21

21

Antimatter

• Matter and antimatter can also come together to release energy in a process called annihilation.

The amount of energy released is equal to:

2mcE

Antimatter

• Comparison of regular matter and it’s antimatter opposite…

Matter vs. AntimatterMATTER ANTIMATTER

Electron Positron

Mass= 9.1E-31 kg Mass= 9.1E-31kg

Charge = Negative Charge = Positive

Antimatter

• How much energy is released when an electron and positron come together and annihilate?

Antimatter

• How much energy is released when an electron and positron come together and annihilate?

smEc

kgEm

kgEm

/80.3

311.9

311.9

2

1

Antimatter

• How much energy is released when an electron and positron come together and annihilate?

smEc

kgEm

kgEm

/80.3

311.9

311.9

2

1

JEE

EEE

EEEE

mcE

13638.1

)169)(312.18(

)80.3)(311.9311.9( 2

2

Electromagnetic Spectrum

• The electromagnetic spectrum comprises all the types of electromagnetic waves from radio waves to gamma rays.

Electromagnetic Spectrum

• All electromagnetic radiation travels at the same speed. The speed of light.

Electromagnetic Spectrum

• The spectrum is made up of the following kinds of waves:

TYPE

Radio

Microwaves

Infrared

Visible Light

Ultraviolet (UV)

X-ray

Gamma

Electromagnetic Spectrum

• The spectrum is made up of the following kinds of waves:

TYPE

Radio

Microwaves

Infrared

Visible Light

Ultraviolet (UV)

X-ray

Gamma

WAVELENGTH (λ)

Longest

Shortest

Electromagnetic Spectrum

• The spectrum is made up of the following kinds of waves:

TYPE

Radio

Microwaves

Infrared

Visible Light

Ultraviolet (UV)

X-ray

Gamma

WAVELENGTH (λ)

Longest

Shortest

FREQUENCY (f)

Lowest

Highest

Electromagnetic Spectrum

• The spectrum is made up of the following kinds of waves:

TYPE

Radio

Microwaves

Infrared

Visible Light

Ultraviolet (UV)

X-ray

Gamma

WAVELENGTH (λ)

Longest

Shortest

FREQUENCY (f)

Lowest

Highest

ENERGY

Least

Most

Test

• 20 Multiple Choice (80 pts)• 1 Constructed Response (20 pts)