Module 16: Reflection and Refraction - Lesson 3: Refraction of Light

Vocabulary flashcards covering the concepts, principles, and mathematical relations of refraction of light, Snell's law, critical angle, and total internal reflection from Module 16, Lesson 3.

Refraction of Light

The bending of light when it passes from one medium to another due to a change in its speed.

Snell's Law of Refraction

A physical law stating that the product of the index of refraction of the first medium and the sine of the angle of incidence is equal to the product of the index of refraction of the second medium and the sine of the angle of refraction: $n_1 \times \sin(\theta_1) = n_2 \times \sin(\theta_2)$.

Index of Refraction ($n$)

The ratio equal to the speed of light in a vacuum ($c \approx 3 \times 10^8\,\text{m/s}$) divided by the speed of light in the medium ($v$), calculated as $n = \frac{c}{v}$.

Light Bending ($n_1 < n_2$)

When light passes from a less optically dense medium to a more optically dense medium, its speed decreases and the refracted ray bends toward the normal line ($\theta_1 > \theta_2$).

Light Bending ($n_1 > n_2$)

When light passes from a denser medium to a less dense medium, its speed increases and the refracted ray bends away from the normal line ($\theta_1 < \theta_2$).

Normal Incidence

The condition where a light beam falls perpendicular to the boundary between two media ($\theta_1 = 0^\circ$), resulting in no deviation in direction and an angle of refraction of $0^\circ$.

Critical Angle ($\theta_c$)

The largest angle of incidence at which light can pass from a denser medium into a less dense medium before total internal reflection occurs, yielding an angle of refraction of $90^\circ$.

Critical Angle Formula

The equation derived from Snell's law when light moves from a denser to a less dense medium ($n_1 > n_2$) with a $90^\circ$ refraction angle: $\sin(\theta_c) = \frac{n_2}{n_1}$.

Total Internal Reflection (TIR)

A phenomenon that occurs when light is completely reflected inside the first medium instead of refracting into the second medium.

Conditions for Total Internal Reflection

Two requirements: light must travel from a medium with a higher refractive index to one with a lower refractive index ($n_1 > n_2$), and the angle of incidence must be greater than the critical angle ($\theta_1 > \theta_c$).

Mirage

An optical illusion that occurs due to the refraction of light caused by differences in air density and temperature, where cooler air has a larger refractive index than the hotter air near the surface.

Optical Density and Speed of Light

The inverse relationship where a larger refractive index $n$ means light slows down more (stronger refraction), whereas a smaller $n$ means light slows down less (weaker refraction).