PHYS-2020: Dr. Luttermoser’s General Physics II
Suggested Homework Problems, Set 4, Spring 2011
The following suggested homework problems will not be graded, but should be done for
review before each Exam. Most of these problems are from your textbook (College Physics,
8th Edition, Serway & Vuille). The solutions are posted in one of four Solution Sets on the
course web page. Try to work these problems out by yourself before looking at the
solutions I have supplied for you.
1. An electromagnetic wave traveling in vacuum has a magnetic field amplitude of 1.5 ×
10−7 T. Find (a) the electric field amplitude and (b) the average power per unit area
associated with the wave. (Solution Set 3-12.)
2. Problem 21.61, Page 730. (Solution Set 3-13.)
3. Problem 28.4, Page 910. (Solution Set 3-14.)
4. Problem 28.7, Page 911. (Solution Set 3-15.)
5. Analyze the Earth-Sun system by following the Bohr model, where the gravitational
force between the Earth (mass m) and the Sun (mass M) replaces the Coulomb force
between the electron and proton (so that F = GMm/r2 and PE = −GMm/r). Show
that (a) the total energy of the Earth in an orbit of radius r is given by E = −GMm/2r,
(b) the radius of the nth orbit is given by rn = r◦ n2 , where r◦ = 10−138 m, and (c)
the energy of the nth orbit is given by En = −E◦ /n2 , where E◦ = G2 M 2 m3/2h̄ 2 =
1.71 × 10182 J. (d) Using the Earth-Sun orbit radius of r = 1.49 × 1011 m, determine
the value of the quantum number n for the Earth. (e) Should you expect to observe
quantum effects in the Earth-Sun system? Why? (Solution Set 3-16.)
6. Problem 28.23, Page 911. (Solution Set 3-17.)
7. Problem 22.9, Page 754. (Solution Set 4-1.)
8. Problem 22.25, Page 755. (Solution Set 4-2.)
9. Problem 22.28, Page 755. (Solution Set 4-3.)
10. Consider a common mirage formed by superheated air just above a roadway. A truck
driver whose eyes are 2.00 m above the road, where n = 1.0003, looks forward. She
has the illusion of seeing a patch of water ahead on the road, where her line of sight
makes an angle of 1.20◦ below the horizontal. Find the index of refraction of the air
just above the road surface. (Hint: Treat this as a problem involving total internal
reflection.) (Solution Set 4-4.)