Question

Which of the following symbols represents half the angle of the cone of light entering the

objective lens or the angle between the normal to the base of the light cone and its side? It is a measure
of the light-gathering ability of lens.
A) d
B) λ
C) n
D) α
E) N. A.

Answer 1

The symbol α (alpha) represents half the angle of the cone of light (acceptance angle) related to a lens's Numerical Aperture (NA), which is a measure of the lens's light-gathering ability and resolving power.

Step-by-step explanation:

The symbol that represents half the angle of the cone of light entering the objective lens or the angle between the normal to the base of the light cone and its side is the Greek letter α (alpha). This angle, which is referred to as half the acceptance angle, is directly related to the Numerical Aperture (NA) of the lens, an essential factor in determining the lens's light-gathering ability and resolving power.

The Numerical Aperture is given by the equation NA = n sin α, where n is the refractive index of the medium between the lens and the specimen, and α is half of the acceptance angle. A higher NA indicates a greater light-gathering capability and an improved ability to resolve fine details.