PHYS345 Electricity and Electronics

Answers for 9/2 Assignment

Answer for 2.9

0.89 mA

Answer for 2.11

a. 2.53 kW
b. 60.7 kW-hr
c. $3.64

Answer for 2.13

The terminal voltage is 7 V.
The delivered power is 7 mW.
The efficiency is 58%.

Answer for 2.38

Assuming a load resistance of 5 ohm,
I find the source resistance to be 0.1 ohm.
If the load resistance is increased to 10 ohm, the terminal voltage will rise to 25.25 V.
If the voltage source can endure it, the short circuit current will be 255 A.

Alternatively, assuming a load resistance of 5 W at 25 V dictates a load resistance of 125 ohm,
Then the source resistance must be 2.5 ohm.
If the load resistance is decreased to 10 ohm, the terminal voltage will drop to 20.4 V.
The short circuit current will be 10.2 A.

Answer for 2.40

300 m of AWG 8 has a resistance of about 0.6 ohm.

Answer for 2.54

a) The initial internal resistance is about 0.06 ohm.

b) One year later the internal resistance has risen to 84 ohm.


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Last updated Sept. 9, 1999.
Copyright George Watson, Univ. of Delaware, 1999.