The Electrical experimenter

May, 1917 THE ELECTRICAL EXPERIMENTER 75
the clftct was due to the action of diffracted
waves on the receiver was further
-liown by the fact tliat witli the rotating
screen in t'le position to allow no transmission
a wire reflector back of the receiver at
varying distances clearly indicated the presence
of nodes and loops at distances apart
wliich showed the wave-length to be that
of the original wave. The average distance
from node to node was found to be slightly
more than 50 cm., making the wavelength
approximately 10() cm.
l-'inal observations were made with the
receiver in the horizontal position at a distance
of 225 cin. from the fixt screen, and
with the oscillator at distances from the
>creen ranging from 120 cm. to 230 cm.
The Law of the Silicon Detector
Since for the final curves obtained the
-jeceiver was so adjusted as to respond only
10 the horizontal component of the transmitted
wave, it seemed possible to use the
(lata to determine the law of response of
the silicon detector with a variation in the
intensity of the incident wave. The data
already obtained showed the response of
the receiver for each position of the rotating
screen. Since ojily the component of
the wave at right angles to the wires of
the screen could be transmitted, the am-
I)litnde of the transmitted wave varied as
the cosine of the angle between the wires
and the vertical. As the receiver was capable
of responding only to horizontal
waves, the transmitted component suffered
a second resolution at the receiver, which
again cut down its amplitude by the cosine
of the same angle. Hence the amj>litude
of the component of the wave to which ic
receiver responded was proportional to the
stpiare of the cosine of the angle between
the vertical and the wires of the screen.
Presumably the ainplitude of the oscillations
set up in the receiver for different
I)ositions of the screen was proportional to
the amplitude of this received component,
and hence to the square of the same angle.
In determining the law only those data
were considered in which the values of the
current obtained without the resonator were
small, l-'or each set of readings two curves
were plotted, with the galvanometer dellections
as abscissae and in one case the
second, in the other the fourth powers of
the cosines of the angles as ordinates.
I'rom these results it seems safe to conclude
that the rectified current is proportional
to the fourth power of the cosine of
the angle between the vertical and the wires
of the rotating screen.
Since the amplitude of the oscillations in
the receiver is presumably proportional to
the square of the cosine, this result indicates
that the rectihed current thru the
silicon detector is proportional to the square
of the oscillating current in the receiver.
.\ustin, in his study of the silicon detector,
reached the conclusion that for alternating
currents of ordinary frequencies and for
ciscillating currents of a frequency of 140,-
000 the rectified currents are approximately
proportional to the square of the alternating
currents. The results of the investigation
of the writers confirm this law for a frequency
of approximately 3X10'-
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