A light ray propagates in Material 1 with index of refraction n1=1.21, strikes an interface, then passes into Material 2 with index of refraction n2=1.35. The angle of incidence at the interface is θ1=14.7∘. Determine the angle of refraction θ2.

Sorry my friend i don't know the answer. i am just in 6th

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.