To increase the efficiency of a heat engine, would it be preferable to produce the same temperature increment by increasing the temperature of the reservoir while maintaining the temperature of the sink constant, or to decrease the temperature of the sink while maintaining the temperature of the reservoir constant? Explain.

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.