PHYS345 Electricity and Electronics

Answer for P2.4

a.  106 ohm

b.  118 ohm

c.  96 ohm

Answer for P2.7

a.  100 A through 0.78 ohm creates 7.8 kW of dissipated power.
Eficiency is 50/(50+7.8) = 87%.

b.  50 A through 0.78 ohm creates 2.0 kW of dissipated power.
Eficiency is 50/(50+2) = 96%.

c.  (500 V, 100 A): $1250; (1000 V, 50 A): $320

Answer for P2.14

A 38 ohm equivalent resistance can be constructed from eight 10 ohm resistors as shown:

Answer to Ch. 2, P2-14

Answer for E2.6

a.  Maximum temperature increase may be 25.4 deg. C, corresponding to maximum ambient temperature of 114 deg. F.

b.  Maximum temperature increase may be 1.7 deg. C, corresponding to maximum operating power of 5.3 W. This corresponds to a current of 230 mA through a 100 ohm resistor.


"http://www.physics.udel.edu/~watson/phys345/protected/exercises/answers/0903.html"
Last updated Sept. 8, 1998.
Copyright George Watson, Univ. of Delaware, 1998.