This preview shows page 1. Sign up to view the full content.
Unformatted text preview: rrent is reduced from 1.50 A to zero in 0.125 s (at a constant rate),
what voltage would be measured between the ends A and B of the short coil (
B By Faraday’s Law, the emf generated in the short coil is where turns,
1.50 A /
cm is the radius of the
solenoid, since there is no field outside its coils. Then 42 turns
A Lenz’s Law says that he emf must be directed to generate
a current in the same direction that the solenoid’s
current had been going, so
and 7 7. [9pt] Answer the following multiple choice questions. You do not need to justify your
answers, but can get partial credit if you show your work.
(a) [3pt] How much work is done per
cycle by a gas following the path ABCA
shown on the
(A) B J (B) J (C) J
(E) C J
J This is the area inside the
triangle. (b) [3pt] An ideal gas may expand from an initial pressure and volume to a final volume
in a variety of ways. In which of the following processes is the heat added to the gas the
(A) Isothermal (B) Adiabatic (C) Isobaric (D) It’s the same in all of these. No heat is added in the adiabatic process:
. The heat added in the isothermal process is
equal to the work done,
The heat added in the isobaric process is
since the temperature increases. The work in this case is
Since the pressure decreases in an isothermal expansion,
Therefore, (c) [3pt] A heat engine is operated between thermal reservoirs at temperatures of 1600 K and
400 K. What is the minimum amount of power that must be put into the engine to run it if the
power output of the engine is 120 kW, according to the laws of thermodynamics?
(A) 90 kW (B) 120 kW (C) 160 kW (D) 240 kW The optimal efficiency is that of the Carnot Cycle, so this gives the minimum (E) 480 kW
: 8 8. [9pt] Answer the following...
View Full Document
This document was uploaded on 03/09/2014 for the course PHYS 222 at Ohio Northern University.
- Spring '12