What is visible spectrum?

Assertion : Red light of visible spectrum contains high energy. Reason : Green light of visible spectrum contains low energy than red light.

Assertion : Blue colour of sky appears due to scattering of blue colour. Reason : Blue colour has shortest wave length in visible spectrum.

The number of wavelenth in the visible spectrum

Generally the approximate limits of visible spectrum are

A thin film of refractive index 1.5 and thickness 4 xx 10^(-5) cm is illuminated by light normal to the surface. What wavelength within the visible spectrum will be intensified in the reflected beam?

A crystalline plate cut parallel to its optical axis is 0.25mm thick and serves as a quarter-wave plate for a wavelength lambda = 530nm . At what other wavelength of visible spectrum will it also serve as a quarter-wave plate? The difference of refractive indices for extraordinary and ordianry rays is assumed to the constant and equal to n_(e) - n_(0) = 0.0090 at all wavelength of the visible spectrum.

The wavelength of visible spectrum extends extends from violet (400 nm) tored (750 nm). Express the corresponding frequency ranges.