light

The EKG showed that

A) Sound is another form of electricity

B) Your body has currents moving through it

C) We emit strong magnetic fields

D) The device charges up your body periodically

The speaker/microphone helped us to see that:

A) Electrical currents can be produced from a moving magnet

B) Sound is really a form of electricity

C) There is no magnetism involved in the conversion from sound to electrical current

D) Sound waves can only be emitted from electrical activity, not the other way around

Light travels VERY FAST – around 300,000 kilometres (186282 miles) per second.

At this speed it can go around the world 8 times in one second.

HIGH energy

LOW energy

The Full Electromagnetic Spectrum

• Visible, Infrared and UV radiation are only part of the full spectrum of electromagnetic radiation

Source: http://www.mhhe.com/physsci/astronomy/arny/instructor/graphics/ch03/0305.html

The Sun’s Radiation Spectrum

• ~ 43% is in the visible range

• ~ 49% is in the near infrared range

• ~ 7% is in the ultraviolet range

• < 1% is x-rays, gamma waves, and radio waves

.

Most of the sun’s radiation is UV, Vis & IR :

Source: Adapted from http://www.ucar.edu/learn/imgcat.htm

Sunset

By passing white light through a prism, you can tell-

A that white light is actually a mixture of different colors

B the mass of the prismC the original source of the lightD that blue light is brighter than white

light

Pick up nov 4

Did you vote?

A) Yes!

B) No…

C) I am not able to vote

Do you think that your vote “counts?”

A) Yes, definitely

B) Only indirectly

C) Only if it is a close call

D) No

November exam

Exam this month – push back a week?

A) 10-Nov is ok

B) Prefer 17-Nov

C) No exam at all is preferable

Final: Wed Dec 15, 4:30-7pm (I think this room)

Do you want to go over the “nuclear” exam in Thursday discussion session?

A) Yes

B) No

C) Indifferent

What about for the circuits hw?

A) Yes

B) No

C) Indifferent

Bees see in UV

Additive Colors

• Red, Green, and Blue light sources can be used to synthesize almost any perceivable color

• Red + Green = Yellow• Red + Blue = Magenta• Green + Blue = Cyan• These three dual-source

colors become the primary colors for subtraction– why? because absence of

green is magenta– absence of red is cyan, etc.

Pick up Nov 9

Term project – to be worth more?

Do you find it fair to change the grading scheme for this course based on a class vote?

A) Yes, if >50% is ok with it.

B) Yes, but only if >67% is ok with it.

C) Not really, but I’ll go along with it.

D) No way!

Term project – to be worth more?

There are multiple ways to slice it –

A) Midterms=13%,final=20%, term=18%

B) Midterms=13%,term=15%

C) Midterms same, final 20%, term 14%

D) Keep the current scheme

3 midterm exams, 14% each:

42%

Final exam: 22%

homeworks: 12%

term project: 12%

discussion activities: 7%

clickers: 5%

TOTAL:100

%

Democracy!

Are you ok with what “we” just decided?

A) Yes

B) No

Invisibility cloak?

One-way mirrors

How do they work?

A) Special engineered one-way material

B) Bright reflected rays on one side

C) Interference of light rays

D) Refraction of light rays

Part 2 - ReflectionReflection from a mirror:

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror

A “light-pipe” works by

A) Diffraction

B) Interference

C) Refraction

D) Dispersion

Seeing colour• The colour an object appears depends on the

colours of light it reflects.

For example, a red book only reflects red light:

White

light

Only red light is

reflected

pick up Nov 11

Polarization

Kindle…

What’s the wavelength of your i>clicker?

A. 1 nm

B. 200 nm

C. 650 nm

D. 10 micron

E. 30 cm

What’s the wavelength of an x-ray?

A. 1 nm

B. 200 nm

C. 650 nm

D. 10 micron

E. 30 cm

HIGH energy

LOW energy

What’s the peak wavelength of a light bulb (about 3000 K)?

A) 10 nm

B) 500 nm

C) 1 micron

D) 10 micron

E) 90 micron

Light bulb = 2500 K

What about you? What peak wavelength do you emit?

A) 10 nm

B) 500 nm

C) 1 micron

D) 10 micron

E) 90 micron

Pick up nov 18

November 2010

Sun Mon Tue Wed Thu Fri Sat

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

We are here!

21 22 23 24 25 26 27

No class this week

28 29 30

CC/Energy

December 2010

Sun Mon Tue Wed Thu Fri Sat

1 2 3 4

Quantum Term project due

5 6 7 8 9 10 11

Quantum Review

12 13 14 15 16 17 18

Final 4:30-7

19 20 21 22 23 24 25

26 27 28 29 30 31

X-rays are particularly sensitive to uranium and plutonium. Why?

A) They’re radioactive

B) They’re dense

C) They have many electrons

D) They are explosive

Xray backscatter…

CT scans

What does the “M” in MRI mean?

A) Metallic

B) Magnetic

C) Mysterious

D) Mapping

E) Microscopic

PET (positron emission tomography)

THz (T-rays)

The depletion of the ozone layer has to do with:

A) Infrared light

B) Visible light

C) UV light

D) microwaves

E) Gamma rays

Ozone is the major reason we are worried about global warming.

A) True

B) False

C) Not sure

Ozone depleting substances

Developed countries Developing countries

Chlorofluorocarbons (CFCs) Phased out end of 1995a Total phase out by 2010

Halons Phased out end of 1993 Total phase out by 2010

Carbon tetrachloride Phased out end of 1995a Total phase out by 2010

Methyl chloroform Phased out end of 1995a Total phase out by 2015

Hydrochlorofluorocarbons (HCFCs)

Freeze from beginning of 1996b

35% reduction by 200475% reduction by 201090% reduction by 2015Total phase out by 2020c

Freeze in 2013 at a base level calculated asthe average of 2009 and 2010 consumption levels10% reduction by 201535% reduction by 202067.5% reduction by 2025Total phase out by 2030d

Hydrobromofluorocarbons (HBFCs)

Phased out end of 1995 Phased out end of 1995

Methyl bromide(horticultural uses)

Freeze in 1995 at 1991 base levele

25% reduction by 199950% reduction by 200170% reduction by 2003Total phase out by 2005

Freeze in 2002 at average 1995-1998 base levele

20% reduction by 2005Total phase out by 2015

Bromochloromethane (BCM)

Phase out by 2002 Phase out by 2002

Review…

Chapter 6: Electricity and Magnetism

Objectives: Learn the vocabulary and units associated with electricityUnderstand how electricity flows around a circuitUnderstand the transportation of electricity from a power plant to your home. Learn how electricity and magnetism are interconnected through the example of a transformer.

Electricity and the Flowing Water Analogy:

Compare this... to this Symbol Units

Charge (Amountof electrons)

Rate of flow I

Narrowing ofpipe, obstacles toflow

Pump Battery

Voltage

Power

Resistance in a wire depends on: 1)2)3)

Chapter 6: Electricity and Magnetism

Objectives: Learn the vocabulary and units associated with electricityUnderstand how electricity flows around a circuitUnderstand the transportation of electricity from a power plant to your home. Learn how electricity and magnetism are interconnected through the example of a transformer.

Electricity and the Flowing Water Analogy:

Compare this... to this Symbol Units

Water Charge (Amountof electrons)

q Coulombs

Rate of flow Current I Amps

Narrowing ofpipe, obstacles toflow

Resistance R Ohms

Pump Battery

Water pressure Voltage V Volts

Pumping rate Power P Watts

Resistance in a wire depends on: 1) material 2) temperature3) thickness

1) Power Plants

A) Steam, coal, turbine, magnetB) Magnet, turbine, coal, steamC) Coal, turbine, magnet, steamD) Coal, steam, turbine, magnet

DC

A B

1) Power Plants

High Voltage power lines:

Using the equation P = IV, we see that high voltage means___________ current.

The goal is to reduce the amount of _________ lost to___________.

The current leaving a power plant is ____________.


A) higherB) lower

1) Power Plants






A) current / powerB) energy / heatC) voltage / currentD) steam / heatE) heat / power

1) Power Plants






A) ACB) DCC) what?

1) Power Plants

Coal, nuclear, natural gas, solar

Water is heated to produce steam

Steam or hydro turns a turbine

Turbine spins a wire through a magnetic field = generator






1) Power Plants







Using the equation P = IV, we see that high voltage means lower current.



1) Power Plants








The goal is to reduce the amount of energy lost to heat.


1) Power Plants








The goal is to reduce the amount of energy lost to heat.

The current leaving a power plant is AC – alternating current.

2) Transformers:

Fuse box ________.

Circuit breaker __________.

Incoming voltage (U.S.) :

Maximum current:

Frequency:

Wires made of:

Voltage is_______Current is_______

Voltage is________Current is________

3) Electricity in the home:

induces induces

2) Transformers:

Fuse box melts.

Circuit breaker resets.

Incoming voltage (U.S.) : 110 V

Maximum current: 15 amps

Frequency: 60 Hz

Wires made of: copper

Changing (AC) primary current

Changing magnetic field in the core

Changing current in the secondary coil

Voltage is high Current is low

Voltage is low Current is high

3) Electricity in the home:

induces induces

1) Power Plants





A) higherB) lower

Interference

How to make a hologram

light

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