Final answer:
The correct expression to calculate the refractive index of glass when light passes from air into glass is 'sinW/sinY', in accordance with Snell's Law.
Step-by-step explanation:
The question prompts us to calculate the refractive index of glass using the proper expression regarding the angles of incidence and refraction when light passes from air into glass. According to Snell's Law, the refractive index n can be found using the ratio of the sine of the angle of incidence (θ1) in the first medium (air) to the sine of the angle of refraction (θ2) in the second medium (glass). This law is expressed as n = sin(θ1) / sin(θ2). In the provided expressions, sinW represents sin(θ1), and sinY represents sin(θ2). Therefore, the correct expression for the refractive index of glass in this context is option A) sinW/sinY.