CCWN 75:59
                                                
1. A 1000 Hz signal. The output is maximum.  2. A 1010 Hz signal.
The switch operating at 2000 Hz results in a signal of 10 Hz
being fed to C1. Over the period of .1 second there will be one
complete_e cycle of the 10 Hz signal. The average voltage of 1
cycle is zero. Therefore, the 1010 Hz signal produces an output
voltage of zero.  3. A 1005 Hz signal. A 5 Hz signal is fed to
C1. During .1 second, .5 of a cycle is placed on C1. This results
in half power, about -6 dB compared to the 1000 Hz signal.  4. A
1020 Hz signal. There are two cycles in the .1 second period fed
to C1. The average over the .1 second period is zero, therefore
the output from the 1020 Hz signal is zero.