________________
It was also found that the velocity of the rebounding electrons did not depend upon the intensity of the impinging light, but on its colour."
53. Satish K. Gupta, op.cit., p. 739
"Human eye is sensitive to only visible part of the electromagnetic spectrum. Different types of detectors are used to detect and study the different parts of the spectrum.
The follwing table gives the wavelength range of different colours of visible light :
Colour Wavelength (m)
Violet3.9 x 107.
Blue 4.5 x 10-7 Green5 x 10-7
Visible Spectrum
54. (a) Ibid., p. 736
4.5 x 10-7 4.5 x 10-7 5.7 x 10-7
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Colour Wavelength (m) Yellow 5.7 x 10-7 Orange 5.9 x 10-7 6.2 × 10-7
Red
Hertz's Experiment
"In 1865, Maxwell had predicted the propagation of electromagnetic waves in the form of varying electric and magnetic fields, which produce each other. It was concluded that the accelerated charges the source of electromagnetic waves. In 1887, Hertz experimentally demonstrated the production of electromagnetic waves by using a spark oscillator and then succeeded in detecting them also.
(b) Text book of Physics (Part II), op.cit, pp.94, 95
"From Maxwell's field equations connecting the electric and the magnetic fields vectors 'E and 'B the wave equation for electromagnetic waves emerged, showing that the disturbances in 'E and 'B can jointly propagate in the form of waves. It was also found that the velocity of these waves in space as calculated from the electric and magnetic parameters was exactly equal to the velocity of light-strongly suggesting that light is a form of electromagnetic waves. It should be noted that all these deductions were logically deduced using theory only from the brilliant formulation of electromagnetic field equations.
113
5.9 x 10-7
6.2 x 10-7 7.8 x 10-7
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