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plates was about 60 cm and the separation between the two spheres was about 2-3 cm. The spheres can be slided over the rods, so as to adjust the gap between them. An induction coil is used to apply a high voltage of several thousand volts across the two metal plates. When the discharge of metal plates takes place in the form of a spark in the gap between spheres S1 and S2, electromagnetic waves are radiated. The waves so radiated can be detected with the help of a detector made of a circular coil and two metal spheres S,' and S1'.
INDUCTION COR
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DETECTOR
Explanation. The high potential difference across the metal plates ionizes the air between the spheres S1 and S2 and allows a path for discharge of plates. During the discharge of plats, a spark is produced between the spheres due to the high potential difference.
(=5 x 107 Hz.). It results in oscillations of charges on the plates at such a high frequency. Therefore, a highly oscillating electric fied is produced across the vertical gap between the two spheres. It, in turn, produces a highly oscillating magnetic field of same frequency in horizontal plane and perpendicular to the gap between the spheres. The oscillating electric and magnetic fields constitute electromagnetic waves of the same frequency (5 x 107 Hz.) and these waves are ratidated from the spark gap."
(b) Text-book of Physics (Std.XIII), part II, Pages 95-97
Here Q1 and Q2 are two metallic spheres. Joined to them are two metallic rods M and N with some space between called spark gap S. The rods are connected to the two terminals of an induction coil to provide high intermittent voltage. The spheres Q1 and Q2 act as capacitors and the rods act as inductors. This arrangement therefore, acts as an oscillagling circuit in which alternately Q' and Q2 acquire positive and negative charges which reverse in their polarity each time a spark passes across the gap S. The process repeats itself rapidly with a definite period.
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The electromagnetic waves generated in the process are detected by another spark gap arrangement R placed at some distance from S. The spheres Q' and Q2 which can be adjusted along the rods M and N are slided so that
तुलसी प्रज्ञा अंक 123
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