A set of two polarizers has either (a) horizontally polarized light, or (b) vertically polarized light incident on it. Discuss why this set of two polarizers will pass through the same fraction of horizontally polarized and vertical polarized light. Explain your reasoning using the properties of light and polarization.
since for both cases (initially horizontally polarized light or initially vertically polarized light) the light that has passed through polarizer 1 has the same polarization angle and intensity, after passing through polarizer 2 the amount of light (and polarization direction) will be same for both cases.