In fig 6, a ray of light in air strikes a glass plate at an angle of incidence 60 degrees, the reflected ray is observed to be perpendicular to the refracted ray, what is the refractive index of the glass
fig 4 represents a block-and-tackle pulley system on which an effort of W newtons supports a load of 120.0N if the efficiency of the system is 40% then the value of W is
