Refraction of Light

Front

Refraction Noun

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[ri-frak-shun]

Back

Refraction

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The bending of a wave, such as light, as it passes at an angle from one medium to another.

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Example: This image shows how a light ray bends (refracts) when it passes from a less dense medium (air) to a denser one (water).

Front

Medium Noun

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[mee-dee-um]

Back

Medium

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A substance or material that a wave, such as light, can travel through to propagate its energy.

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Example: A wave changes its speed and wavelength when it travels from one medium to another, which is the principle behind light refraction.

Front

Index of Refraction Noun

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[in-deks ov ri-frak-shun]

Back

Index of Refraction

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A dimensionless number describing how fast light travels through a medium, calculated as a ratio to its vacuum speed.

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Example: This diagram shows a ray of light bending as it passes from one medium to another, which is called refraction. The angles shown help calculate the index of refraction.

Front

Angle of Incidence Noun

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[ang-guhl ov in-si-dens]

Back

Angle of Incidence

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The angle formed between an incoming light ray and the normal line perpendicular to the surface it strikes.

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Example: This diagram shows a light ray hitting a new material. The angle of incidence ('i') is the angle between the incoming ray and the normal line.

Front

Angle of Refraction Noun

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[ang-guhl ov ri-frak-shun]

Back

Angle of Refraction

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The angle between a refracted light ray and the normal line after it has passed through a surface boundary.

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Example: This diagram shows a ray of light bending as it enters a transparent block, illustrating how the angle of refraction is measured from the normal line.

Front

Normal Noun

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[nor-muhl]

Back

Normal

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An imaginary line drawn perpendicular to a surface at the exact point where a light ray strikes it.

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Example: The 'Normal' is an imaginary line (dotted) drawn perpendicular to the surface where light changes medium, used as a reference to measure angles.

Front

Snell's Law Noun

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[snels law]

Back

Snell's Law

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A formula relating the indices of refraction of two mediums to the angles of incidence and refraction.

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Example: This diagram shows a light ray bending as it enters a new medium, illustrating Snell's Law, which relates the angles to the materials' refractive indices.

Front

Wavefront Noun

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[weiv-fruhnt]

Back

Wavefront

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An imaginary surface representing points of a wave that are in the same phase, such as wave crests.

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Example: This diagram shows that a wavefront is an imaginary line connecting the crests (or any identical points) of adjacent waves as they travel forward.

Front

Total Internal Reflection Noun

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[toh-tl in-tur-nl ri-flek-shun]

Back

Total Internal Reflection

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The complete reflection of a light ray back into its original medium when striking a boundary at a large angle.

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Example: When light travels from a denser medium (water) to a less dense one (air), it can be completely reflected back, trapping the light inside the water stream.

Front

Critical Angle Noun

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[krit-i-kuhl ang-guhl]

Back

Critical Angle

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The specific angle of incidence at which a refracted light ray travels along the boundary between two mediums.

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Example: This diagram shows a light ray traveling from water to air at the critical angle (C), causing the refracted ray to travel along the boundary.