Reflection of Light at Plane and Curved

When light bounces off surfaces, it follows the law of reflection: the angle of incidence equals the angle of reflection. At plane (flat) surfaces like mirrors in your bathroom, light reflects to form virtual images that appear behind the mirror at the same distance as the object is in front.

Curved surfaces work differently. Concave mirrors (curved inward) can form real, inverted images when objects are placed beyond the focal point, or magnified virtual images when closer. Think of how a shaving mirror magnifies your face. Convex mirrors (curved outward) always produce diminished virtual images, which is why they're used as security mirrors in shops and banks across Nigeria.

The position and nature of images depend on where the object sits relative to the mirror's focal point and centre of curvature. Understanding ray diagrams helps predict image formation accurately.

When light hits a mirror surface, it bounces back following the law of reflection: the angle of incidence equals the angle of reflection. A plane mirror is flat and produces an upright, virtual image the same size as the object. Think of how you see yourself in your bathroom mirror at home—that's a plane mirror at work.

Concave mirrors curve inward like a spoon's inside. They can produce either magnified or diminished images depending on where the object is placed. Convex mirrors curve outward like a spoon's back, always producing smaller, virtual images. You'll see convex mirrors used as security mirrors in Nigerian shops and banks because they show a wide area.

The key difference is that concave mirrors can magnify objects while convex mirrors always reduce the image size. Understanding where objects sit relative to the focal point helps predict the image type produced.

The mirror formula is simply a mathematical equation that helps you find where an image appears in a curved mirror. Think of it like this: when you look at your reflection in a curved mirror at a barbing salon, the formula tells you exactly where that image forms and how big it will be.

The formula is: 1/f = 1/u + 1/v, where f is the focal length, u is the object distance, and v is the image distance. All distances are measured from the mirror's surface.

To use this formula correctly, you need to identify what the question is asking for. If they give you the focal length and object distance, you can find where the image appears. If they give you two distances, you can find the focal length.

The key is understanding that concave mirrors (curved inward) create real images when objects are beyond the focal point, while convex mirrors (curved outward) always produce virtual images that appear behind the mirror.

Linear magnification tells you how many times bigger or smaller an image appears compared to the object. For curved mirrors, we calculate it using the formula: magnification (m) equals image height divided by object height. You can also use m = -v/u, where v is the image distance and u is the object distance from the mirror.

Think of a barber's concave mirror in Lagos—when you sit close to it, your face appears much larger, maybe three times bigger. That's magnification of 3. A negative magnification means the image is inverted. Convex mirrors, like those on car sides, always produce smaller, upright images with magnification less than 1.

The closer you place an object to a concave mirror, the larger the magnification becomes. Understanding this relationship helps solve most JAMB questions on curved mirrors.

When light hits a smooth surface, it bounces back following two simple rules: the angle at which light hits equals the angle at which it bounces, and both angles are measured from an imaginary line perpendicular to the surface. This is the law of reflection, and it works the same way whether light bounces off a flat mirror or a curved one.

Think about how you see yourself clearly in a bathroom mirror at home—that's plane reflection working perfectly. With curved mirrors like those used in car headlights or satellite dishes, light behaves differently because the surface curves. These curved surfaces can focus light into a bright spot or spread it wide, depending on their shape.

Understanding these principles helps explain everything from why you look straight in a plane mirror to how curved mirrors concentrate sunlight. The key is remembering that light always obeys the same reflection rules.

A periscope uses two plane mirrors arranged at 45-degree angles to help you see over obstacles. Light reflects off the top mirror, then bounces to the bottom mirror before reaching your eye. This is why soldiers and submarine operators use periscopes to observe enemies without being seen. You can even make one with two small mirrors and a cardboard tube—it actually works!

A kaleidoscope works differently. It contains three plane mirrors arranged in a triangle, creating beautiful repeated patterns. When you look through it and rotate it, you see the same pattern repeated multiple times because light bounces between all three mirrors simultaneously. The coloured glass pieces inside reflect and bounce around, creating those stunning symmetrical designs children play with.

Both devices rely on the law of reflection: the angle of incidence equals the angle of reflection. Without this law, neither device would function properly.

Reflection happens when light bounces off a surface. At a plane (flat) mirror, light reflects at the same angle it hits the surface—this is the law of reflection. The angle of incidence equals the angle of reflection, both measured from an imaginary perpendicular line called the normal.

Curved surfaces behave differently. A concave mirror curves inward and can concentrate light rays to a focal point, which is why it's used in torches and searchlights. A convex mirror curves outward and spreads light rays apart, making it useful for car wing mirrors and security monitors in Nigerian shops.

The sextant is a navigation instrument that uses mirrors and light reflection to measure angles between celestial bodies and the horizon. Sailors and pilots use it to determine their location at sea, though modern GPS has reduced its importance.

The laws of reflection state that the angle of incidence equals the angle of reflection, and both angles are measured from the normal line (an imaginary perpendicular line to the surface). When light hits a mirror, it bounces off following these rules regardless of the surface type.

With plane mirrors like those in your bathroom, light reflects smoothly in one direction, creating a clear image. Curved mirrors work differently. Concave mirrors (curving inward) converge light rays to a focal point, useful in torches and car headlights. Convex mirrors (curving outward) scatter light rays, which is why vehicle side mirrors prevent blind spots.

Think of a car's headlight at night—the concave mirror concentrates light from the bulb into a powerful beam down the road. Understanding how light behaves on these surfaces is essential for optics questions.

When light travels from air into glass, it bends and slows down. This bending is called refraction, and we measure how much bending happens using the refractive index. The refractive index of a material is simply the ratio of the speed of light in air to its speed in that material. For most types of glass, this value is around 1.5, meaning light travels 1.5 times slower in glass than in air.

You can see this effect daily when looking at a drinking glass filled with water—the spoon inside appears bent at the surface. That bending happens because light refracts as it exits the water and glass into air. To find the exact refractive index experimentally, you measure the angle of incidence and angle of refraction, then apply Snell's Law: n = sin(i)/sin(r).