![Page 1: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/1.jpg)
Astro 109 Lecture 9: Light and Heat October 1, 2014
Please pick up a gra.ng (small, clear piece of plas.c)
on your way into class. This is yours to keep!
![Page 2: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/2.jpg)
Constella=on of the day: Lyra
• Small constella=on with a big, bright star: Vega, the fiEh brightest star in the sky and (along with Altair and Deneb) defining one vertex of the “summer triangle.”
• In Greek mythology, represented the lyre of Orpheus, who unsuccessfully tried to rescue his wife Eurydice from Hades.
Image credit: IAU/Sky & Telescope
![Page 3: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/3.jpg)
Why astronomers like Lyra
• Vega is orbited by a debris disk that represents a late stage in the forma=on of a new planetary system, in which larger pebbles, rocks, and boulders are ground into dust by collisions – likely driven by the gravita=onal tugs of planets.
Marsh et al. (2006)
![Page 4: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/4.jpg)
Organiza=onal reminders • Midterm will be in class on Wednesday, October 15th.
• Four more sets of in-‐person office hours before the midterm: this Friday 10/3 (3:00-‐4:30pm in Scoa 102), next Tuesday 10/7 (3:00-‐4:30pm in Serin 401), next Friday 10/10, and Tuesday 10/14. Please stop by (or send me an email to make an appointment) if you need to talk!
• Reading for Friday: T7, T8, T9 (Tools of Science boxes for chapters 7, 8, and 9).
• Homework # 4 due this Friday in Sakai. (Your clicker and homework scores
should be showing up in the Sakai gradebook. I will have to make a few small adjustments for clicker ques=ons that Sakai doesn’t grade correctly.)
• G. Luzzi: please iden=fy yourself aEer class!
![Page 5: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/5.jpg)
1/3 of class is aaending – how about you? LA DAY TIME CAMPUS ROOM
Elsie Lee Monday 1:10-‐2:30pm College Ave Kreeger 117
Isabel Kennedy Monday 6:40-‐8:00pm Livingston Tillea 111
Ryan DeGregorio Tuesday 8:10-‐9:30pm Busch ARC 326
Adrian Casper Wednesday 1:10-‐2:30pm College Ave Kreeger 117
Zac Csorny Wednesday 2:50-‐4:10pm College Ave Kreeger 117
Ragen Patel Thursday 2:50-‐4:10pm College Ave Kreeger 117
Anthony Xing Thursday 5:00-‐6:20pm Livingston Tillea 111
• All students are welcome to aaend; if you are gerng 6/10 or less on homeworks, you are strongly encouraged to aaend.
![Page 6: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/6.jpg)
Sign up for study groups in Sakai • Wednesday/Thursday this week and Monday/Tuesday
next week are now available for signup via the “Sign-‐up” tab in Sakai (note: Sec=on 4 for today is already full).
• Regarding extra credit: – If you want extra credit, please show up on =me and par=cipate ac=vely.
– You can see your current total in Sakai gradebook in “Study group extra credit” field.
• Ques=ons from last year’s midterm you should be able to
answer aEer today’s lecture: #1 (62%), #12 (37% -‐ now you will have seen c = λν), #30 (37% -‐ caught up with material).
![Page 7: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/7.jpg)
Finishing up on gravity…
![Page 8: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/8.jpg)
Sept. 27 ar=st’s concep=on
Tidal forces can be destruc.ve, too • If =dal force on a moon is stronger than gravita=onal force of the moon on itself, the moon will disintegrate!
![Page 9: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/9.jpg)
Another niEy effect of gravity: resonances • Some physical systems have “natural” frequencies where a modest input can have a drama=c effect (e.g., wine glass shaaered by opera singer’s voice). These are resonances.
• Another example: repeatedly pushing a child on a swing at the swing’s “natural” frequency yields huge amplitudes.
Image credit: www.lilsugar.com
![Page 10: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/10.jpg)
Gravity at work: orbital resonances • Galilean moons, again: in the =me it takes Ganymede to make one orbit of Jupiter, Europa makes exactly two orbits and Io makes exactly four orbits of Jupiter.
• Coincidence? No! • Io, Europa, and Ganymede have a stable orbital resonance, which is maintained by the regular gravita=onal tugs they give each other as they orit the planet. (Not all resonances are stable, however.) – This is a liale like three children who are all pushing each others’ swings – doesn’t work on a playground, but can work with gravity.
![Page 11: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/11.jpg)
Orbital resonances • Watch the Galilean moons do their dance (note: they never all line up on the same side of the planet)…
Image credit: Wikipedia
![Page 12: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/12.jpg)
Extreme orbital resonances • In the =me it takes Neptune to make three orbits of the
Sun, Pluto makes exactly two orbits of the Sun.
• Since Neptune and Pluto return to the same posi=ons every 3 x 165 = 2 x 248 years, they stay far away from each other, and Pluto is protected from bullying by Neptune. – If not for the resonance, Pluto would have been kicked out of its orbit by Neptune a long =me ago…
Image credit: D. Gary
![Page 13: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/13.jpg)
Saturn’s moons Mimas and Tethys have orbital periods of 0.94 and 1.88 days, respec=vely, defining a stable 4:2 orbital resonance. Which statement about these moons is correct?
Group clicker ques=on # 1
A. An observer on Mimas would always see the same face of Tethys at all =mes.
B. Mimas completes a single orbit of Saturn during the =me it takes Tethys to complete two orbits of Saturn.
C. Mimas and Tethys will never be on the same side of Saturn at the same =me.
D. Mimas will only pass between Tethys and Saturn once in every two of its orbits around Saturn.
E. Once Mimas is fully opera=onal, the Galac=c Empire will use it to destroy Tethys.
Image credit: NASA/Cassini
![Page 14: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/14.jpg)
Today’s (main) subject: light and heat!
General rule: where there’s heat, there’s light of some sort.
![Page 15: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/15.jpg)
Speed of light: first es=mate
c = 3⇥ 108 m/shap://www.ux1.eiu.edu/~cfadd/1150/01Intro/std.html
Danish astronomy Ole Rømer (1675): =me between eclipses of Io by Jupiter is longer when Earth is moving away. Right idea, right conclusion (light has a finite speed), but wrong answer; his es=mate was 25% below true value:
![Page 16: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/16.jpg)
c stands for cosmic speed limit!
In a vacuum (i.e., empty space): + Nothing moves faster than c. + Speed of light is independent
of wavelength. (There’s no speed “bonus” if you happen to be a very energe=c photon!)
In a transparent medium (air, water, glass, etc.): + Speed of light is less than c. + Speed of light can some=mes
depend on wavelength.
Image credit: abc3miscellany.blogspot.com
![Page 17: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/17.jpg)
The visible spectrum
Oct. 2
A prism splits light into its cons=tuent colors by taking advantage of the varia=on of the speed of light with wavelength in glass. (Your gra=ng has a similar effect for different reasons.) Roy G. Biv = red, orange, yellow, green, blue, indigo, violet – from long to short wavelength.
![Page 18: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/18.jpg)
The electromagne.c spectrum
Light is more than meets the eye!– or at least, more than the eye can see. Astronomers now have telescopes at all these wavelengths.
![Page 19: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/19.jpg)
Oct. 2
![Page 20: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/20.jpg)
Demonstra=ons!
![Page 21: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/21.jpg)
Light acts like a par=cle… and a wave
Wikipedia
![Page 22: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/22.jpg)
Diffrac=on
aperture
![Page 23: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/23.jpg)
Proper=es of waves
frequency, ν (cycles per second, s-‐1, or Hz)
� ⇥ = c (speed)
![Page 24: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/24.jpg)
![Page 25: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/25.jpg)
Why “electromagne=c”?
hap://www.nrc-‐cnrc.gc.ca/eng/projects/inms/op=cal-‐comb.html
![Page 26: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/26.jpg)
Green light has a wavelength of around 500 nm (or 500 billionths of a meter). What is its frequency?
Example
� = 500⇥ 10�9 m
= 5⇥ 10�7 m
� ⇥ = c
⇥ =c
�
=3⇥ 108 m/s
5⇥ 10�7 m
=30⇥ 107
5⇥ 10�7s�1
= 6⇥ 1014 Hz
![Page 27: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/27.jpg)
WRSU-‐FM broadcasts at 88.7 MHz. What is the wavelength of the radio waves?
Example
⇥ = 88.7 MHz= 88.7⇥ 106 s�1
= 8.87⇥ 107 s�1
� =c
⇥
=3⇥ 108 m/s
8.87⇥ 107 s�1
= 3.4 m
![Page 28: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/28.jpg)
The frequency of red light is about half the frequency of violet light. In vacuum, how does the wavelength of red light compare with the wavelength of violet light?
A. four =mes larger B. twice as large C. the same D. half as large E. one quarter as large
Clicker ques=on # 2
![Page 29: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/29.jpg)
The frequency of red light is about half the frequency of violet light. In vacuum, how does the speed of red light compare with the speed of violet light?
A. four =mes larger B. twice as large C. the same D. half as large E. one quarter as large
Clicker ques=on # 3
![Page 30: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/30.jpg)
Percep=on
Sound: • amplitude = loudness • frequency = pitch
Light: • amplitude = brightness • frequency or wavelength = color • color and brightness are not the same!
![Page 31: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/31.jpg)
Hot things glow: thermal radia=on
![Page 32: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/32.jpg)
Oct. 2
Wikipedia, “thermography”
…and so do not-‐so-‐hot things
![Page 33: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/33.jpg)
Blackbody spectrum
TF =95TC + 32
TC =59(TF � 32)
TK = TC + 273Oct. 2
Idealized object that is opaque and nonreflec=ve; need not be black per se!
![Page 34: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/34.jpg)
Demonstra=on!
(Note: gra=ng is a giE of the Department of Physics and Astronomy… don’t use it to try to look at the Sun, but feel free to send Prof. Baker pictures to post in Sakai “art gallery”!)
![Page 35: Astro&109&Lecture&9:& Lightand&Heatajbaker/ph109/midterm/Lec... · Astro&109&Lecture&9:& Lightand&Heat October&1,&2014& & Please&pick&up&a&gra.ng&(small,&clear&piece&of&plas.c)& on&your&way&into&class.&This&is&yours&to&keep!&](https://reader033.vdocuments.net/reader033/viewer/2022052611/5f048b547e708231d40e7f0c/html5/thumbnails/35.jpg)
As a solid body gets cooler, it emits electromagne=c radia=on
A. that is brighter and whose spectrum peaks at shorter wavelengths.
B. that is brighter and whose spectrum peaks at longer wavelengths.
C. that is fainter and whose spectrum peaks at shorter wavelengths.
D. that is fainter and whose spectrum peaks at longer wavelengths.
E. that is clammier.
Clicker ques=on # 4