Physics: Waves, Sound, and Light - Dispersion, Colour Mixing, and Optical Applications

Grade 8IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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v_{red} > v_{violet}

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Primary Colours of Light: Red, Green, and Blue (RGB). These are the three colours that can be mixed to create white light.

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Red + Green = Yellow

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Red + Green + Blue = White

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Colour Subtraction: The process of filters or pigments absorbing certain wavelengths and reflecting others. For example, a red filter absorbs all colours except red, which it transmits.

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n

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Optical Applications: Lenses are used to refract light for specific purposes. A convex (converging) lens is used in magnifying glasses and to correct hyperopia (far-sightedness), whereas a concave (diverging) lens is used to correct myopia (near-sightedness).

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i

📐Formulae

n = \frac{\sin(i)}{\sin(r)}

n = \frac{c}{v}

v = f \lambda

\sin(C) = \frac{1}{n}

💡Examples

Problem 1:

40^\circ

Solution:

n = \frac{\sin(40^\circ)}{\sin(25^\circ)}

Explanation:

We use Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the refractive index of the second medium relative to the first.

Problem 2:

Determine the color of a blue shirt when it is viewed under pure yellow light.

Solution:

The shirt will appear black.

Explanation:

Red + Green = Yellow

Problem 3:

2.42

Solution:

v = \frac{c}{n}

Explanation:

n = \frac{c}{v}