Question

A photographic film can be exposed (affected) by light with a minimum energy of 2.65 x 10-19 J. How many of the colors of the visible light can expose this film?

Answer 1

All of the colors of the visible light spectrum can expose the film

Explanation:

energy can be calculated with the following formula;

E=\frac{hc}{λ}

where h is planck constant = 6.62 * 10^{-34}

c is speed of light = 3* 10^{8}

λ is wavelength

visible light comprises of the ROYGBIV colors, which are red, orange yellow, green, blue, indigo and violet. For any of these colors to affect the film their energy must be greater than the minimum energy required to expose the film. However, violet with the smallest wavelength has the highest energy. we would calculate the energy of red color in the visible spectrum to see if it surpasses this minimum energy.

highest possible wavelength(red color) = 750*10^{-9}m

E(red light)=\frac{6.62*10^{-34} *3*10^{8} }{750 * 10^{-9} }

E= 2.646 * 10^{-19} J

≈ 2.65 * 10^{-19} J

this energy is for the highest wavelength exhibited by red color. for lower wavelengths of red color in the spectrum the film will be exposed and also this indicates that other colors in the spectrum will excite the film as they have very much lower wavelengths