Quiz 1

Student Last Name____________First Name________________________9/23/2014
1. Sound, light, and gamma rays are all forms of electromagnetic radiation.
2. In a vacuum, electromagnetic waves all travel at the same speed.
3. A blackbody emits all its radiation at a single wavelength or frequency.
4. For an emission spectrum produced by a container of hydrogen gas, changing the amount of hydrogen in the container will change the color of the lines in the spectrum.
5. The wavelengths of the emission lines produced by an element are different from the wavelengths of the absorption lines produced by the same element.
6. The energy of a photon is inversely proportional to the wavelength of the radiation.
7. An electron can have any energy within an atom, so long as that energy is above the ground-state energy.
8. The _____ of a wave is the distance between any two adjacent wave crests.
9. When a charged particle moves, information about this motion is transmitted through space via the particle’s changing _____ and _____ fields.
10. Earth’s atmosphere has low opacity for three forms of electromagnetic radiation. They are _____, _____, and _____.
11. The peak of an object’s emitted radiation occurs at a frequency or wavelength determined by the object’s _____.
12. Two identical objects have temperatures of 1000 K and 1200 K. It is observed that one of the objects emits roughly twice as much radiation as the other. Which one is it? _____.
13. Fraunhofer discovered absorption lines in the spectrum of _____.
14. When moving to a lower energy level in an atom, an electron _____ a photon of a specific energy.
15. The radiation received from a source moving away from the observer will be shifted toward _____ frequencies by the _____ effect.
16. An x- wave moving through the medium has a frequency of 200 Hz and a wavelength of 6 m. What is the speed of  x- wave  in the medium?
17. What is the wavelength of a 10-MHz (“FM 10”) radio signal?
18. What would be the frequency of an electromagnetic wave having a wavelength equal to Earth’s diameter? In what part of the electromagnetic spectrum would such a wave lie?
19. The blackbody emission spectrum of object A peaks in the ultraviolet region of the electromagnetic spectrum, at a wavelength of 200 nm. That of object B peaks in the red region, at 650 nm. According to Wien’s law, how many times hotter than B is A? According to Stefan’s law, how many times more energy per unit area does A radiate per second?
20. Normal human body temperature is about 37°C. What is this temperature in kelvins? What is the peak wavelength emitted by a person with this temperature? In what part of the spectrum does this lie?
21. According to the Stefan-Boltzmann law, how much energy is radiated into space per unit time by each square meter of the Sun’s surface (see More Precisely 2-2)? If the Sun’s radius is 696,000 km, what is the total power output of the Sun?
22. By what factor does the energy of a 1000 MHz photon exceed that of a 10 MHz radio photon?
23. How many different photons (that is, photons of different frequencies) can be emitted as a hydrogen atom in the second excited state falls back, directly or indirectly, to the ground state? What are their wavelengths? What about a hydrogen atom in the third excited state?
24. The line (Sec. 2.6) of a certain star is received on Earth at a wavelength of 656 nm. What is the star’s radial velocity with respect to Earth?
25. Imagine you are observing a spacecraft moving in a circular orbit of radius 100,000 km around a distant planet. You happen to be located in the plane of the spacecraft’s orbit. You find that the spacecraft’s radio signal varies periodically in wavelength between 2.99964 m and 3.00036 m. Assuming that the radio is broadcasting normally, at a constant wavelength, what is the mass of the planet?