Physics Review Chapters 27 and 28 Unit Test Wednesday May 6, 2015

(22.) 1. A certain metal has a threshold frequency of 5 X 10 (14). What is the work function?

(22.) 1. Write answer here (show your work!):

(23.) 2. A gamma ray has a wavelength of 5 X 10 (-14) m. What is the momentum of the wave?

(23.) 2. Write answer here (show your work!):

(24.) 3. A 0.1 kg ball files through the air at 25 m/s. (a) What is the deBroglie wavelength of the ball? (b) why don't we see any observable wave behavior?

(24.) 3. Write answer here (show your work!):

(25.) 4. What velocity would an electron need to have if its wave length was 5 X 10 (-30) m?

(25.) 4. Write answer here (show your work!):

(26.) 5. Estimate the peak wavelength for (a) water at 12 degrees C (b) for another substance at 273 K

(26.) 5. Write answer here (show your work!):

(27.) 1. A black body absorbs and emits what percentage of incoming and outgoing light?

(27.) 1. It absorbs 100% and emits 100%.

(28.) 2. Classify the following colors according to their temperature: red, orange, yellow, green, blue, indigo, violet.

(28.) 2. RoyGiBiv.

(29.) 3. Planck's Constant

(29.) 3. a. sets an upper limit to the amount of energy that can be absorbed or emitted. b. sets a lower limit to the amount of energy that can be absorbed or emitted.

(30.) 4. The ratio of energy to frequency for a given photon gives:

(30.) 4. Planck's Constant

(31.) 5. If X-rays increase their wavelength what happens to the frequency?

(31.) 5. Frequency decreases.

(32.) 6. If X-rays decrease their wavelength what happens to the frequency?

(32.) 6. The frequency increases.

(33.) 7. What happens to the frequency of an x-ray when it's scattered after hitting a substance?

(33.) 7. The energy after it scatters is less than before. Frequency decreases.

(34.) 8. What happens to the wavelength of a particle if it speeds up?

(34.) 8. It gets shorter.

(35.) 1. Webassign: How hot is a metal being welded if it radiates most strongly at 570 nm?

(35.) 1. Webassign: Write answer here (show Your Work!) :

(36.) 2. Webassign: Estimate the peak wavelength for radiation from the following sources, assuming blackbody emission.

(36.) 2. (a) ice at -2 degrees C ____________________um Show your work!!!!

(37.) 2. Webassign: Estimate the peak wavelength for radiation from the following sources, assuming blackbody emission.

(37.) 2. (b) a floodlamp at 2800 k ___________________ nm Show Your Work!!!!!

(38) 2. Webassign: Estimate the peak wavelength for radiation from the following sources, assuming blackbody emission.

(38.) 2. (c) helium at 8 k ______________mm Show Your work!!!!!

(39.) 2. Webassign: Estimate the peak wavelength for radiation from the following sources, assuming blackbody emission.

(39.) 2. (d) the universe at T=2.725k ____________ cm Show Your work!!!!

(40.) 2. Continues: In What region of the EM Spectrum is each?

(40.) Pick one answer from the below choices: * far infrared, near infrared, microwave, and infrared respectively. * near infrared, far infrared, microwave, and infrared respectively * near infrared, infrared, far infrared, and microwave respectively. * far infrared, infrared, near infrared and microwave respectively * infrared, microwave, near infrared, and far infrared respectively. * infrared, microwave, far infrared, and near infrared respectively.

(41.) 3. What is the energy of photons (joules) emitted by a 103.1 MHz radio station?

(41.) 3. Write answer here: ______________ J Show Your Work!!!

(42.) 4. Calculate the momentum of a photon of yellow light of wavelength 6.10 X 10 (-7) m

(42.) 4. Write answer here: ______________ kg.m/s Show Your Work!!!

(43.) 5. What is the momentum of a ^ = 0.29 nm X-ray photon?

(43.) 5. Write answer here: _______________ kg.m/s Show Your Work!!!!

(44.) 6. When UV light of wavelength 285 nm falls on a metal surface, the maximum kinetic energy of emitted electrons is 1.40 eV. What is the work function of the metal?

(44.) 6. Write answer here: _____________m Show Your Work!!!!!

(45.) 7. Calculate the wavelength of a 0.20 kg ball traveling at 0.10 m/s.

(45.) 7. Write answer here: __________m Show Your Work!!!!!

(46.) 8. The Big Bang Theory states that the beginning of the Universe was accompanied by a huge burst of photons. Those photons are still present today and make up the so called cosmic microwave background radiation. The Universe radiates like a blackbody with a temperature of about 2.7 K. Calculate the peak wavelength of this radiation.

(46.) 8. Write anser here: + or - ____________m/s

(47.) 9. If an electron's position can be measured to an accuracy of 1.2 X 10 (-8) m, how accurately can its speed be known?

(47.) 9. Write answer here: + or - _____________m/s

1. What is a Quantum?

1. A discrete quantity of energy proportional in magnitude to the frequency of radiation it represents.

10. Does the particle view of an electron or the wave view of an electron better explain the discreteness of electron energy levels?

10. The particle view.

11. Why is the helium atom smaller than a hydrogen atom?

11. Helium is a smaller atom than hydrogen because the extra positive charge in the helium nucleus pulls the electrons in tighter than the single proton in the hydrogen nucleus pulls its electron.

12. Why are the heaviest elements no appreciably larger than the lightest elements?

12. More heavier the element means having more of the protons and the neurons and due to the force of these increased protons they are not appreciably larger than the lightest elements.

13. What is quantum mechanics?

13. The branch of mechanics that deals with the mathematical description of the motion and interaction of subatomic particles, incorporating the concepts of quantization of energy, wave-particle duality, the uncertainty principle, and the correspondence principle.

14. Can the momenta and positions of electrons in an atom be measured with certainty?

14. No. Deals with the work done with Heisenburg Principle.

15. What does it mean to say that a certain quantity is quantized?

15. It cannot be a fraction. Must be a multiple of a unit base.

16. What evidence can you sight for the wave nature of light?

16. Compton effect and the photoelectric effect.

17. What photon has the most energy: one from infrared, visible, or ultraviolet light?

17. Ultraviolet

18. Sun tanning produces cell damage in the skin. Why is UV light capable of producing this damage while infrared radiation is not?

18. The energy of infrared is.

19. Electrons in one electron beam have a greater speed than those in another. Which electrons have the longer de Broglie wavelength?

19. Slower electrons have higher De-Broglie wavelength as slower electrons have lower momentum. Wavelength = Planck's constant / Momentum

2. What is a quantum of light called?

2. Photon

20. We do not notice the wavelength of moving matter in our ordinary experience. Why?

20. Because the wavelength is extraordinarily small therefore the frequency is extraordinarily high.

21. Why would helium rather than hydrogen more readily leak through an inflated rubber balloon?

21. Hydrogen is diatomic in nature (two atoms) H2. Helium, a Noble gas is mono atomic. Helium is also smaller, since it has two protons in a tightly held and nicely stable first s orbital. He is smaller and can effuse faster than H2

3. Which has more energy per photon: red light or blue light?

3. Blue Light

4. What is the photoelectric Effect?

4. The photoelectric effect is the observation that many metals emit electrons when light shines upon them.

5. Will bright blue light eject more electrons than dim light of same frequency?

5. Blue

6. Does the photoelectric effect support the particle model of light?

6. It supports the wave model of light.

7. Do particles of matter have wave properties? Who was the first physicist to give a convincing answer to this question?

7. Yes. Louis de Broglie

8. As the speed of a particle increases, does it associate wavelength increase or decrease?

8. The wavelength decreases as it speeds up.

9. Doe the diffraction of an electron beam support the particle model or the wave model of electrons?

9. It supports the wave model.

THIS IS THE TOP CARD PHYSICS CHAPTERS 27 and 28 UNIT TEST IS ON WEDNESDAY, MAY 6, 2015.

THIS IS THE TOP CARD PHYSICS CHAPTERS 27 and 28 UNIT TEST IS ON WEDNESDAY, MAY 6, 2015.