66. 4) VelocityThe number of wavelengths per cm is called1) Wavelength2) Wave number 3) AmplitudeThe height of crest (or) depth of trough of a wave is called1) Wavelength2) Amphitude 3) Wave number67.4) None68.69.In electromagnetic radiation, which of the following has greater wavelength thanvisible light1) U.V rays2) I.R rays3) Gamma rays4) X-raysPhoto electric effect is observed in case of1) Caesium2) Magnesium 3) Aluminium 4) NonThe minimum frequency of light required to eject the electrons from an atom is called ...1) Threshold frequency2) Chemical frequency3) Kinetic energy4) None70.

66. 4) VelocityThe number of wavelengths per cm is called1) Waveleng

1.	66. 4) VelocityThe number of wavelengths per cm is called1) Wavelength2) Wave number 3) AmplitudeThe height of crest (or) depth of trough of a wave is called1) Wavelength2) Amphitude 3) Wave number67.4) None68.69.In electromagnetic radiation, which of the following has greater wavelength thanvisible light1) U.V rays2) I.R rays3) Gamma rays4) X-raysPhoto electric effect is observed in case of1) Caesium2) Magnesium 3) Aluminium 4) NonThe minimum frequency of light required to eject the electrons from an atom is called ...1) Threshold frequency2) Chemical frequency3) Kinetic energy4) None70.
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