Ever wondered how light behaves when it hits different surfaces or passes through various mediums? This chapter is all about understanding these interactions using some simple formulas and laws. Let’s dive into the basics of light, mirrors, and lenses to see how they work.
Notations Explained
- u = The distance of the object from the mirror or lens
- v = The distance of the image (either in mirror or lens calculations)
- f = Focal length, which is a key part of calculating image formation
- c = The speed of light in a vacuum
- v = The speed of light in a particular medium
- P = The power of a lens (used to determine how strong a lens is)
The Mirror Formula
The mirror formula is a quick way to figure out the relationship between the object distance, the image distance, and the focal length of a mirror. It goes like this:
Mirror Formula: 1/v + 1/u = 1/f
Magnification in Mirrors
Magnification shows how much bigger or smaller the image is compared to the object. For mirrors, it’s given by:
Magnification (m) in Mirror: m = (Height of the image)/(Height of the object) = h'/h = v/u
Snell’s Law – What It Means
Snell’s Law tells us how light bends when it moves from one medium to another. It’s all about the angles and looks like this:
Snell’s Law: sin i / sin r = constant
Understanding Refractive Index
The refractive index is basically a number that tells us how much light slows down in a particular medium compared to air or a vacuum. Here’s how we find it:
- n21 = (Speed of light in medium 1) / (Speed of light in medium 2) = v1 / v2
- n12 = (Speed of light in medium 2) / (Speed of light in medium 1) = v2 / v1
- nm = (Speed of light in air) / (Speed of light in the medium) = c / v
The Lens Formula
The lens formula works similarly to the mirror formula but applies to lenses:
Lens Formula: 1/v - 1/u = 1/f
Magnification in Lenses
For lenses, magnification (m) is given by the ratio of the height of the image to the height of the object, just like in mirrors:
Magnification (m) in Lens: m = (Height of the Image) / (Height of the object) = h'/h = v/u
What is the Power of a Lens?
The power of a lens tells us how strong it is. A higher power means the lens bends light more. It’s calculated using this formula:
Power (P): P = 1/f
Download the Full Formula List
If you want to have all the formulas in one place, you can download the complete list from the link below:
Download Formula List for Chapter - Light – Reflection and RefractionConclusion
So, this chapter gives us the tools to understand how light behaves when it reflects off surfaces or passes through different materials. By mastering these basics, we get a solid foundation in the physics of light and optics.