MIRRORS

Most mirrors have a glass-like feel—they're typically heavy and fragile. However, despite this similarity, the experience of looking into a mirror versus a regular glass surface, like a window, is quite different.

During daylight, window glass is transparent, allowing you to view the world outside. But at night, if your room is brightly lit and you look at the same window, you'll notice your own reflection instead. A mirror, in contrast, consistently shows your reflection whether it's day or night, as long as there's sufficient light.

To grasp why mirrors and window glass behave so differently, it's important to explore the roles of metals and insulators

3. Metals and Insulators

• Metals are typically shiny materials—like steel utensils, aluminum pressure cookers, or the coins you carry. They're usually strong, tough to break, and have a silvery appearance.
• Metals also respond quickly to temperature changes and are good conductors of electricity. That’s why it’s dangerous to touch a live electrical socket with something like a metal spoon.
• In contrast, insulators—such as glass, wood, and plastic—do not conduct electricity well and generally lack that metallic shine.
• Electricity flows through the movement of electrons. Atoms contain both positively charged protons and negatively charged electrons. In metals, electrons are free to move—they behave like energetic kids, roaming between atoms, creating what’s often called an "electron sea."
• In insulators, however, electrons stay close to their respective atoms and don’t move around freely. So when a battery is connected, electrons can travel easily through metals but not through insulators.
• Interestingly, this same difference in how electrons behave with electricity also affects how they respond to light

4. Interaction of light and electrons

• Light is a type of electromagnetic wave. A wave, in general, is a repeating disturbance that travels from one location to another. For example, dropping a stone in water creates ripples, while speaking generates sound waves in the air.
• When light reaches us, it comes in the form of electromagnetic waves—regular patterns of changing electric and magnetic fields. Electric fields can move electrons, as seen in electronic devices like watches, while magnetic fields are what hold magnets to your fridge. When these fields begin to change rhythmically over time, they produce electromagnetic waves—what we perceive as light.
• Electrons respond in interesting ways when exposed to light. Similar to how we move rhythmically when pushed on a swing, electrons also begin to oscillate when struck by light, almost like they’re dancing.
• However, this “dance” varies between materials. In metals, where electrons are free to move around in a shared "electron sea," they respond collectively—like a choreographed group performance. In contrast, electrons in insulators remain close to their own atoms, moving individually in place.
• This difference in electron behavior determines how a material interacts with light. In metals, the synchronized movement of electrons blocks light, reflecting it back instead of letting it pass through.
• That’s why light bounces off metallic surfaces. In insulators, electrons only wiggle slightly within their atoms, allowing most of the light to pass through.
• This is why transparent insulators like glass allow light to pass, while metals typically do not.
• It also explains why you can see your reflection clearly in a steel spoon—light from your face bounces straight back into your eyes. But during the day, when you look at a window, most of the light from your face passes through the glass, making your reflection faint.
• At night, with less light outside and more indoors, a small amount reflects back from the glass, letting you see yourself faintly