Indicates a 90 degree angle of incidence. Which term is correct?

Indicates a 90 degree angle of incidence. Which term is correct?

• A. Normal incidence
• B. Oblique incidence
• C. Grazing incidence
• D. Specular incidence

Answer: (A)

Normal incidence describes a beam that hits a surface at right angles. If the angle between the incoming ray and the surface is 90 degrees, the ray is perpendicular to the surface—precisely normal incidence. Oblique incidence would be any non-perpendicular angle, grazing incidence refers to a ray traveling nearly parallel to the surface, and specular incidence isn’t a standard term for the angle itself. So a 90-degree angle to the surface corresponds to normal incidence.

Normal incidence describes a beam that hits a surface at right angles. If the angle between the incoming ray and the surface is 90 degrees, the ray is perpendicular to the surface—precisely normal incidence. Oblique incidence would be any non-perpendicular angle, grazing incidence refers to a ray traveling nearly parallel to the surface, and specular incidence isn’t a standard term for the angle itself. So a 90-degree angle to the surface corresponds to normal incidence.