(a) Dispersion of light and colours

When white light passes through a prism or raindrop, it bends and splits into its component colours—red, orange, yellow, green, blue, indigo, and violet. This happens because each colour has a different wavelength, and different wavelengths bend at different angles when passing through a transparent material. Red light has the longest wavelength and bends the least, while violet has the shortest wavelength and bends the most.

You see this phenomenon every day after rain in Nigeria when rainbows appear across the sky. Water droplets act as tiny prisms, splitting sunlight into beautiful bands of colour. The electromagnetic spectrum includes these visible colours plus invisible radiation like ultraviolet and infrared rays.

Understanding dispersion helps explain why objects appear coloured—they reflect certain wavelengths and absorb others.

When white light passes through a prism or water droplet, it splits into different colours because each colour has a different wavelength and bends at slightly different angles. This splitting is called dispersion. The separated colours arranged in order from red to violet form the visible spectrum. Red light has the longest wavelength and bends least, while violet has the shortest wavelength and bends most.

You see this happening naturally when rainbow forms after rain in Nigeria. Sunlight enters water droplets, disperses into colours, reflects inside, and exits to create that beautiful arc of colours you see in the sky. Different colours have different frequencies too—red is slowest and violet is fastest.

Understanding that wavelength determines which colour appears where helps you predict how light behaves in different materials.

When white light passes through a prism, it splits into different colours—red, orange, yellow, green, blue, indigo, and violet. This separation happens because each colour has a different wavelength. Red light has the longest wavelength (about 700 nm), while violet has the shortest (about 400 nm). Since different wavelengths travel at slightly different speeds through glass, they bend at different angles, creating a spectrum.

You see this naturally when rain creates a rainbow after a storm in Lagos or Abuja. Sunlight enters water droplets, disperses into colours, and reflects back to your eyes. The sun is the light source, our eyes detect the colours, and the water droplets act as tiny prisms.

Understanding wavelengths helps explain why different colours behave differently. Violet bends more than red because it has a shorter wavelength and travels slower through the medium.

Monochromatic light simply means light of one colour only. The word breaks down as "mono" (one) and "chromatic" (colour). When light consists of just a single wavelength or a very narrow range of wavelengths, it appears as one pure colour. Think of it like this: ordinary white light from the sun contains all colours mixed together, but monochromatic light has been filtered to show only one colour.

A practical Nigerian example is the red light from traffic lights at busy intersections in Lagos or Abuja. That red light is close to monochromatic because it's designed to show one specific colour. Similarly, the yellow sodium lamps used on some Nigerian roads produce nearly monochromatic light. Laser lights are the purest examples of monochromatic light in nature.

Dispersion of light happens when white light splits into its seven component colours as it passes through a prism or water droplet. Each colour has a different wavelength, and when light slows down entering a denser medium, shorter wavelengths like violet bend more than longer wavelengths like red. This is why you see a rainbow after rain in Nigeria—sunlight passes through water droplets in the air, and each colour bends at slightly different angles, creating that beautiful arc across the sky. The order is always red, orange, yellow, green, blue, indigo, and violet (ROYGBIV). This happens because violet light has the shortest wavelength and refracts most, while red light has the longest wavelength and refracts least. Understanding that different colours behave differently during refraction is crucial for grasping why dispersion occurs.

When white light passes through a prism, it splits into seven colours: red, orange, yellow, green, blue, indigo, and violet. This separation happens because each colour has a different wavelength, and the prism bends them at slightly different angles. Red light bends the least while violet bends the most. You can see this effect in rainbows after Nigerian harmattan rains when sunlight passes through water droplets in the air.

An electroscope is an instrument that detects electric charges. When you bring a charged object near its metal plate, the leaves inside spread apart, showing charge presence. It's useful in physics labs for testing whether objects are electrically charged without measuring the exact amount.

When white light passes through a prism or water droplet, it separates into different colours. This happens because different colours have different wavelengths, and each wavelength bends at a slightly different angle when entering a new medium. Red light bends the least while violet bends the most, creating the rainbow effect you see after rain in Nigeria.

Think of it like this: a rainbow appearing in the sky after a storm shows how water droplets disperse sunlight into its seven component colours. The water acts like millions of tiny prisms. Each colour travels at a different speed through the droplet, causing this beautiful separation.

Dispersion occurs because the refractive index of a material varies with wavelength. Shorter wavelengths experience more bending than longer ones, which is why violet always appears on the inner edge of a rainbow while red appears on the outer edge.

Dispersion happens when white light passes through a prism or water droplet and splits into seven different colours: red, orange, yellow, green, blue, indigo, and violet. Each colour has a different wavelength, and the prism bends each wavelength by a slightly different amount. Red light bends the least while violet bends the most. This is why rainbows appear after rain in Nigeria—sunlight enters water droplets, gets dispersed into colours, and reflects back to your eyes. The same principle explains why a glass of water can create a mini rainbow on your wall when sunlight shines through it. Understanding that dispersion depends on wavelength is crucial because JAMB often asks you to identify which colour bends most or explain why white light separates.

When white light passes through a prism or raindrops, different colours bend at different angles because they travel at different speeds through the medium. This separation is dispersion. Each colour has a specific wavelength, and shorter wavelengths (violet) bend more than longer ones (red). Think of how you see a rainbow after rain in Nigeria—that's dispersion in action.

The electric field concept relates here because light is an electromagnetic wave created by oscillating electric and magnetic fields. You can deduce the electric field strength expression using the relationship between light intensity and the amplitude of electric field oscillations. The intensity is proportional to the square of the electric field amplitude: I ∝ E². From this, you derive that E = √(2I/ε₀c), where I is intensity, ε₀ is permittivity, and c is light speed.

When white light passes through a prism, it separates into different colours—this is dispersion. Each colour has a different wavelength, and the prism bends (refracts) each colour by a slightly different amount. Red light bends the least while violet bends the most, which is why you see a rainbow spectrum spreading out.

Think of it like this: when sunlight passes through water droplets after rain in Nigeria, you see a rainbow arcing across the sky. The water droplets act like tiny prisms, dispersing the white sunlight into its component colours. This happens because different colours travel at different speeds inside the water droplet.

Understanding dispersion helps explain why we see colours in nature. The ability of a material to disperse light depends on its refractive index for different wavelengths.

When white light passes through a prism or water droplet, it bends and separates into its component colours—red, orange, yellow, green, blue, indigo, and violet. This separation happens because each colour has a different wavelength, and different wavelengths bend at slightly different angles when passing through a medium like glass or water. Red light bends least while violet bends most. This is why rainbows appear in Nigeria after afternoon rains, with colours arranged in a specific order across the sky. The same principle explains why a glass of water can create a mini rainbow when sunlight shines through it. Understanding that dispersion depends on wavelength and the refractive index of the material is crucial for solving related problems.

When white light passes through a prism, it splits into different colours. This happens because different colours have different wavelengths and travel at different speeds through transparent materials like glass or water. Red light bends less than violet light, so they separate. You see this naturally when rainbow forms after rain in Nigeria—sunlight refracts through water droplets in the air, separating into red, orange, yellow, green, blue, indigo, and violet.

The colours you see depend on the wavelength of light. Longer wavelengths (red) bend less while shorter wavelengths (violet) bend more. This separation is called dispersion. Understanding that white light is actually a mixture of all colours helps explain why prisms create rainbows.

When white light passes through a prism or water droplet, it splits into different colours. This happens because different colours have different wavelengths and travel at slightly different speeds through the material. Red light bends less than violet light, so they separate and spread out. This spreading is called dispersion.

You see this beautifully after Nigerian rainstorms when a rainbow forms in the sky. Sunlight enters millions of water droplets, disperses into its component colours, and reflects back to your eyes arranged in order: red on the outside, violet on the inside.

The key thing is that white light isn't actually one colour—it's a mixture of all colours. Dispersion just reveals what's already there, arranging them by wavelength from longest to shortest.

Dispersion happens when white light passes through a prism or raindrop and splits into its seven component colours: red, orange, yellow, green, blue, indigo and violet. Each colour bends at a slightly different angle because they have different wavelengths. Red light bends the least while violet bends the most. This is why you see a rainbow after rain in Nigeria—sunlight enters water droplets in the air, gets dispersed, and creates that beautiful arc of colours across the sky. The colours always appear in the same order because this is determined by physics, not chance. Understanding that different colours have different refractive indices is crucial for solving dispersion problems in your exams.