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Critical Topics and Their Significance for the UPSC CSE Examination on April 08, 2025

Daily Insights and Initiatives for UPSC Exam Notes: Comprehensive explanations and high-quality material provided regularly for students

The magic of a mirror: how is it able to show your reflection?

For Preliminary Examination:  Current events of national and international Significance

For Mains Examination: GS III - Science & Technology

Context:

Dressing up is probably one of the most annoying things. You stand in front of a mirror and try to find the right combination of clothes of various colours hoping you look more tolerable to people. This is probably one trait that distinguishes us from other animals: we spend a few good minutes every morning staring at a mirror.

Read about:

Total internal refraction

Electrons

Key takeaways:

A mirror is an object with a smooth, polished surface that reflects light, forming an image of whatever is in front of it. Most modern mirrors consist of a thin layer of reflective material, such as silver or aluminum, applied to the back of a piece of glass.

Here's a breakdown of how mirrors work:

• Reflection of Light: When light strikes a mirror's surface, it doesn't pass through. Instead, it bounces off, or reflects.
• Smooth Surface: The key to a good mirror is its smooth surface. Rough surfaces scatter light in many directions (diffuse reflection), which doesn't create a clear image. Mirrors have a very smooth surface at a microscopic level, allowing for specular reflection, where light rays bounce off in a predictable way.
• Angle of Incidence Equals Angle of Reflection: The law of reflection states that the angle at which a light ray hits the mirror (the angle of incidence) is equal to the angle at which it bounces off (the angle of reflection).
• Image Formation: When you stand in front of a mirror, light rays from your body travel to the mirror and reflect back to your eyes. Your brain interprets these reflected light rays as coming from a point behind the mirror, creating the illusion of an image.
• Virtual Image: The image formed by a typical flat mirror (called a plane mirror) is a virtual image. This means the light rays don't actually meet behind the mirror; your brain just perceives them as originating from there. Virtual images are upright and appear to be the same distance behind the mirror as the object is in front.
• Lateral Inversion (Left-Right Reversal): Plane mirrors also produce an image that is reversed from left to right. If you raise your right hand, your reflection appears to raise its left hand. This is because the mirror reverses the front-to-back orientation