Topics 2.1-2.2Pages 410-459

Name: ________________________________Date: __________________________________

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Chapter 2: The

Electromagne

tic Spectr

um

Topic 2.1 –

Electrom

What is Radiation?- _____________________________ is energy emitted in the form of particles or waves.

o Energy travels from the Sun to Earth in the form of radiation

- ________________________________________________ : (EMR) is a wave that consists of a changing electric field and a changing magnetic field travelling at right angles to one another

o In chapter 1, we learned that electric fields are produced by charged objects and magnetic fields are produced by moving charges.

Use the following diagram to answer the questions on the next page.

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Topic 2.1 –

Electrom

1. A straight line drawn from the center to the perimeter of a circle is called a radius. Suggest an explanation for the origins of the word radiation.

2. In Chapter 1 you learned that in addition to solar wind, astronauts need to be protected from cosmic rays. Cosmic rays are large, positively charged particles emitted from stars in distant parts of the galaxy.

a. Explain whether or not cosmic rays can be classified as a type of electromagnetic radiation.

b. Describe evidence from your own experiences that supports the idea that distant stars emit electromagnetic radiation that travels to Earth.

Transmitting Energy Through Vibrations:Here are some examples of ways that energy is transmitted through vibrations:

- Water (splashing, boats, etc.)- Sound- What about radiation from the sun???

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Use the following information to answer the next 2 questions.

1. Identify ways in which your body could detect the electromagnetic radiation emitted by the light bulb.

2. Explain how the electromagnetic radiation is able to travel from the filament to the surrounding glass if the air inside the bulb is almost completely removed.

Describing EMR:- EMR is a ___________________________________________

o A transverse wave is a wave in which the vibrations are at right angles (perpendicular) to the wave’s direction of travel.

- All transverse waves have ________________ and ______________________________.

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- The ____________________ is the distance of one cycle (crest to crest for example)o The wavelength is the distance from a point on one wave to the same point

on the next wave.o The symbol for wavelength is lamda, λ

Determining Wavelength:1. Determine the wavelength of this EMR

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2. Determine the wavelength of the following TWO EMR.

Frequency:- Frequency is the number of cycles that pass a certain point per second.

o The symbol for frequency is fo Units for frequency = cycles per second = hertz (Hz)

- Example: A frequency of 3 cycles per second = 3 Hz

Examples:1. The following diagram shows an illustration of an electromagnetic radiation passing a detector. Use this information to determine the frequency of the EMR.

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a. In 1.00ms, 740 radio waves pass the antenna of a radio.

b. In 1.00µs, 2450 microwaves pass through a point on a piece of cheese in a microwave oven

The Universal Wave Equation- The measurement of wavelength and frequency not only describe key

characteristics of waves, they also provide a very convenient way to calculate the speed of a wave.

- When talking about EMR travelling through a vacuum (like space), regardless of wavelength or frequency, the speed will always be 3.00 x 108 m/s.

o This value is typically referred to as the speed of light and represented by letter c.

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SOOOO….. The formula can be represented as……..

OR

C = λf

This may be helpful……Recall the formula for velocity:

V = ΔdΔtV = Velocity (m/s)d = distance (m)t = time (s)

Examples:1. An excited atom in a neon sign emits electromagnetic radiation with a wavelength

of 6.4 x 10-7 m.a. Calculate the frequency of the electromagnetic radiation

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b. If the neon sign was located 25.0 m from an observer, how long would it take the light from the sign to reach the observer?

2. The antenna of a FM radio station broadcasts electromagnetic radiation with a frequency of 104.5 MHz. A driver in a car is receiving these FM radio waves while travelling down a highway at 90.0 km/hr, or 25.0 m/s.

a. Calculate the wavelength of the electromagnetic radiation

b. Some of the FM radio waves can leave Earth’s atmosphere and travel into space. Calculate how long it would take these radio waves to reach the Moon which is located about 3.84 x 108 m from Earth.

c. Use your answer to part b. to determine how far the car would travel in the same time it takes the radio wave to travel from Earth to the Moon.

Practice Questions, Page 421, #7 & 8

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The Electromagnetic Spectrum:- The electromagnetic spectrum is the wide band of different types of EMR ranging

from _____________________________ to ______________________________.

EMR from the Sun:

- Sun performs ____________________- As you move farther away from the surface of the sun, the ________________

increases- As you move farther away from the surface of the sun, the ___________ also

increases- The sun emits radiation from across the entire EMR spectrum

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- Most of this radiant energy does NOT reach the Earth’s surface, due to the effects of our atmosphere and our magnetic field.

- Typically, only infrared, radio waves, visible light, UVA and UVB enter our atmosphere.

- By studying the Universe across the spectrum we can get a more complete understanding of objects in space.

- The light from each part of the electromagnetic spectrum brings us valuable and unique information.

o __________________________ bring us information about high energy phenomena such as black holes, supernova remnants, hot gas, and neutron stars.

o ___________________________ reveals hot stars and quasars while visible light shows us warmer stars, planets, nebulae, and galaxies.

o In the _________________________ we see cool stars, regions of star birth, cool dusty regions of space, and the core of our galaxy.

o Radiation in the _________________________ shows us cold molecular clouds and the radiation left over from the Big Bang.

X-ray image showing hot gas

near the center of our Milky Way Galaxy (CXO).

Ultraviolet view of hot white dwarf stars in a nearby

galaxy (ASTRO-1).

Visible light image showing stars of different colors.

Infrared view of glowing dust near the center of our Galaxy (2MASS).

Radio image of a supernova

remnant (NRAO).

It is a very, VERY good idea to take a look through your text book on pages 422 – 432. I did not go into detail in your notes package about the different section of the electromagnetic spectrum, but your textbook does a beautiful job of this. Please take the time to do this…. It will be well worth your time.

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Practice Questions, Page 422, #9, 10

Practice Questions, Page 428, #16-18

Practice Questions, Page 432, #22-25

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Using EMR from beyond Earth- Electromagnetic radiation from objects in outer space has played an essential role

in human existence for a long time.o In this section, we will see how the characteristics of the electromagnetic

spectrum have been applied to study _____________________________.

Our Nearest Star- Our sun…….

o In the core of the sun, the temperature is estimated at about 15,000,000oCo ___________________________ (process where two smaller nuclei join to form a

larger nucleus, releasing energy…..)o A _______________________________ is a very powerful eruption in the Sun’s

atmosphere that is triggered by the realignment of the Sun’s magnetic field lines.

Practice Questions; Page 440 #29 & 30

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Topic 2.2 - Astronomy

Analyzing Starlight- We have the technology to be able to tell what stars are made of, if they are

moving or not and in what direction they are moving.- We can collect radiation data from stars in order to analyze these things.

o We can use a ______________________ to separate the radiation into each wavelength

o Or we can use a ______________________________ which is a piece of glass or plastic with thousands of tightly spaced parallel lines etched on its surface which produces the spectrum.

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What does the radiation from stars look like?

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Examples:

1. Use the radiation spectrums to explain what star 1 and start 2 are composed of.

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Hydrogen

Helium

Sodium

Star 1

Star 2

2. Use the following spectral lines to identify the composition of the star.

The Doppler Effect:- A change in pitch is called the _____________________________ and is caused by the

change in a sound’s wavelength.

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How does this relate to a star??? If a star is approaching you, its wavelengths become compressed

Sooo… the dark lines in the stars spectrum shift towards the blue end. If a star is going away from you, the wavelengths will be longer

Sooo… The dark lines in the stars spectrum shift towards the red end…. RED SHIFTED!

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Helium

Star 1

Hydrogen

Star 2

The Doppler Effect Explained…..

The Evolution of stars:- Use your text book on pages 452 to identify different vocabulary of stars and how

they are formed. Indicate if the stars are low-mass, intermediate mass or high mass stars

1. Red Giant

2. Nebula

3. White Dwarf

4. Neutron Star

5. Pulsar

6. Supernova

7. Blackhole

8. Super giant

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Properties of Visible Light:1. Reflection - the bouncing off of waves from any surface they hit.

a. ___________________________________ - the angle of incidence is equal to the angle of reflection.

b. Reflection on a parabola - incoming rays are parallel and become concentrated as they reflect off the surface and become focused.

i. Applications: Reflecting telescopes, satellites and parabolic microphones

c. Terminology: reflected ray,

incident ray, normal, angle of incidence, angle of

reflection

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2. Refraction – the change in direction of a wave as it travels from one medium to another.

a. Refraction is the ________________________ of a wave as it enters a medium where its speed is different.

i. Qualitative generalizations 1. when light moves into a medium with a higher index of refraction

it bends _________________________________2. when light moves into a medium with a lower index of refraction

it bends _______________________________________.b. The fact that each color or wavelength of light refracts differently is what

causes white light to spread apart and form a rainbow of colors as it passes through a prism. Red light bends the least and blue/violet light the most.

c. The refraction of light when it passes from a fast medium to a slow medium

bends the light ray toward the normal to the boundary between the two media.

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3. Diffractiona. Diffraction is the ___________________________________ of light as it passes around the

edge of an object.b. The amount of bending depends on the relative size of the wavelength of light to

the size of the openingc. If the opening is ____________________________than the light’s wavelength, the

bending will be almost _____________________________d. However, if the two are closer in size or equal, the amount of bending is

considerable, and easily seen with the naked eye.

Physics Unit Review A1. The gravitational field strength at a point 3.99 x 107 m from the centre of Earth is expressed in scientific

notation, is a.bc × 10–d N/kg. The values of a, b, c, and d are _____, _____, _____, and _____. 22

a b c d

2. Which diagram represents the electric field lines between two small electrically charged spheres?A. B. C. D.

3. A 1.00 kW toaster is plugged into a 120 V power source. The current in the toaster is A. 0.833 AB. 1.20 AC. 12.0 AD. 8.33 A

4. Three 10 resistors are connected as shown. The total resistance of the circuit is ____ .

5. Which of the following situations induces the greatest current flow in the coil? (All magnets and coils are identical.)

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6. Which of the following correctly shows the magnetic field between two opposite magnetic poles?

Use the following information to answer the next question.

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Steel paperclips are attached to a string that is attached to a table. The clips remain suspended beneath a magnet.

7. Which diagram best represents the magnetic poles of the paper clips?

8. Compared with visible light, X rays have a A. higher speed in a vacuumB. lower frequencyC. higher frequencyD. longer wavelengthE.

9. Electromagnetic radiation of frequency 5.00 x 1021 Hz is best described as beingA. radioB. gammaC. infraredD. Ultraviolet

10. A student sets up four sources of electromagnetic radiation. The brightness (intensity) of the sources are equal. Which source emits radiation with the greatest energy?A. infrared

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A B

C D

B. green light

C. ultraviolet D. red light

11. Which diagram above depicts the correct pathway of a reflected light ray? A. I B. II C. III D. IV

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12. Spectrum I is an example of an _i spectrum, and the relative temperature of gas I is _ii . The statement above is completed by the information in row

13.Several objects are heated so that they glow. The object that is the hottest is the one that emitsA. white lightB. mostly yellow lightC. mostly infrared radiationD. mostly red light

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Use the following information to answer the next two questions.

The diagram below shows four spectral lines produced by glowing hydrogen gas in a laboratory and four spectral lines produced by hydrogen gas as seen in the light from Barnard’s Star.

14. The spectrum from Bernard’s star shows that the star is ___i__ because the spectral lines are shifted towards the __ii__ portion of the electromagnetic spectrum.The statement is best completed by the information in row

Row i iiA. moving towards Earth high frequencyB. moving towards Earth low frequencyC. moving away from

Earthhigh frequency

D. moving away from Earth

low frequency

15. When Bernard’s star has burned its fuel, it will end its life as aA. black holeB. white dwarfC. red giantD. main sequence star

16. The composition of Mars’ atmosphere has been determined through spectroscopic analysis. The visible spectrum of Mars contains narrow, dark lines caused by

A. diffraction of light between Mars and EarthB. refraction of electromagnetic radiation by Earth’s magnetic fieldC. gases in Mars’ atmosphere absorbing certain electromagnetic radiationD. gases in Mars’ atmosphere emitting certain electromagnetic radiation

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Answers1. 0.251 = 2.51 x 10-1 so record 25112. B3. D4. 30 5. D, stronger magnets, faster, there is more magnetic energy and mechanical eergy to convert to electrical

energy6. B7. D8. C9. B10. C11. C12. C13. A14. A15. B16. C

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