As light from air to water to glass, it will refract. the best explanation for this would be
a) glass is less transparent than water, which is less transparent than air.
b) light will be transmitted into the new medium each time it reaches a boundary.
c) a light wave reflects off molecules as it travels, this causes the light to bend,
d) the speed of a wave slows down as it travels at different speed in different media.

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)