14. A solenoid with N turns has a length I and a redius r. For what current will the energy density within the solenoid be u?
(A)
(B)
(C)
(D)
(E) nome of the above. 

10. N is the number of particles in the systen, V is the volume of the system, T is the tem- perature of the system. Which of the following is a possible expression of the entropy of a macroscopic system? (A) NIn(N/V),(B)NkBET, (C)NkBT/V, (D) NInV+N, (E) none of the above.

11. Which quantity changes during the free expansion of an ideal gas? (A)energy,(B)entropy, (C)temperature, (D) above all, .(E) none of the above.

12. When an external electric feld is applied to a dielecttic, (A)the electric dipoles align antiparallel to the external feld, the eloctric feld in the interior becomes smaller than external electric field,(B) the electric dipoles align parallel to the external field, the electric field in the interior becomes smaller than external electric feld, (C) the electric dipoles align antiparallel to the external feld, the electric feld in the interior becomes greater than external electtic feld, (D) the electric dipoles align parallel to the external feld, the electric field in the interior becomes greater than external electric field, (E) none of the above.

13. A long, straight wire carries a constant current I. A metal rod of length I moves at constant velocity on rails of negliglble resistance that terminate in a resistor R, as shown in the figire. The induced current in the resistor is (A)(B)(C) (D) (E) none of the above.

15. Consider refraction of a wave, what changes as wave enters from medium I to mediurn II with different index of refraction? (i) wavelength changes (ii) frequency changes (iii) amplitude changes (iv) wave speed changes (A)(i) (iii),(B)(i)(ii) (iv), (C)(ii) (iv), (D) (ii)(iii)(iv), (E) none of the above.

16. In a double-slit experiment the slits are 0.5 mmn wide and their centers are separated by 1.5 mm. The interference maxima of what order are missing? (A)m = 2,(B)m= 4, (C)m =6, (D) all above, (E) none of the above.

17. Light strikes a plate in an evacuated chamber. The result is that electrons are etnitted from the plate P and are collected by C. In the process a single'photon gives up all its energy to a singje electron. The maximum poasible kinetic energy of the photoelectrons, , is related to the energy of a photon, hf, by (Φ is work function) (A)(B) (C) (D) hf = 함mยma로 (E) none of the above.

18. Which of the following has the correct dimension of a bulk modulus? (A) Pa,(B)Pa /s, (C)N/m3 (D) kg/m3 (E) none of the above.

19. How does the intensity of radiation changes with the distance r from the source? Let d bo the spatial dimension. (A) proportional to ,(B)proportional to , (C)proportional to, (D) proportional to (E) none of the above.

20. Here is a simple way to estimate the ground-state energy for a particle in a potential k/r. Suppoee the ground state xnomentum and position satisfies Heisenberg's uncertainty principle pr ~ h, the Kinetic energy in the ground state is Minimize the total energy of the system you find that ground state energy is roughly (A)(B)(C)(D) (E) none of the above