SOLVING PROBLEMS 19 and 20
April 19, 2010
Problem 19
(like 24.19): A Hertzian resonator has a capacitance of 1 picoFarad and inductance of 1
microHenry. The spark gap breaks down at 10 kV and the resonator oscillates with an energy decay time
of 5 microseconds. What is the frequency of the oscillation?
What do you know?
First of all, it doesn’t matter that it is Hertzian or Schmertzian. The angular
frequency is 1 over the square root of L times C so the frequency is
2
10
1
2
1
9
LC
f
Hz = 159 MHz
a)
159 MHz;
b)
159 mHz;
c)
159 kHz;
d)
159 GHz;
e)
159 Hz.
What is the initial power being radiated?
What do you know?
The initial power will be the initial stored energy one half C Vsquared, divided by
the energy decay time or
10
10
10
10
2
5
8
12
2
CV
P
W.
a)
10 W;
b)
1 W;
c)
1 mW;
d)
10 kW;
e)
1
W.
Problem 20
(like 24.46): The polarization angles in stack of 9 perfect polarizing sheets are each set 10
O
from the previous one to make a device for rotating the polarization by 90
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 Spring '04
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 Capacitance, Inductance, Energy, Light, Polarization, Hertz, energy decay time

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