Question

How does the light have to enter the glass?
(a) To produce a large amount of bending?
(b) For no refraction to happen?

Answer 1

Hint: The bending of light (as well as sound, water, and other waves) when it flows from one transparent medium into another is known as refraction. Lenses, magnifying glasses, prisms, and rainbows are all conceivable because of this bending through refraction. Even our eyes are reliant on light bending.

Complete answer:
Snell's law (also known as Snell–Descartes law or the law of refraction) is a formula used to describe the connection between the angles of incidence and refraction when light or other waves pass through a border between two separate isotropic media, such as water, glass, or air.

According to Snell's law, the ratio of the sines of the angles of incidence and refraction is equal to the ratio of phase velocities in the two media, or the reciprocal of the indices of refraction:
$\dfrac{{\sin {\theta _2}}}{{\sin {\theta _1}}} = \dfrac{{{v_2}}}{{{v_1}}} = \dfrac{{{n_1}}}{{{n_2}}}$
with each $\theta $ equaling the angle measured from the boundary's normal, v equaling the velocity of light in the respective media (SI units are metres per second, or m/s), and n equaling the refractive index (which is unitless) of the respective medium.

(a) To achieve a high degree of bending, light rays must enter the glass at an oblique angle, resulting in a large angle of incidence. The refractive index of the two mediums determines the angle of refraction or the degree of bending of light.
(b) The light beam will not bend if it strikes the glass block at a straight angle (90°) to the surface (no refraction).

Note: Light will be refracted to a lesser or higher angle when it travels through the boundary between media, based on the respective refractive indices of the two media. The normal line, which is perpendicular to the boundary, is used to calculate these angles.Because light is slowed in water, light going from air to water will be refracted towards the normal line; light going from water to air will be refracted away from the normal line.