Type any topic from your CBSE syllabus and get it explained simply, with a diagram and a video.
Chapter 9 · Light: Reflection and Refraction
A curved mirror is just a small piece of a sphere: concave curves inward, convex curves outward, and a handful of labelled points describe both.
Move the object closer to a concave mirror and the image flips from real-and-small to virtual-and-huge; exactly at the focus, it disappears.
A convex mirror always gives the same kind of image: small, upright, and behind the mirror, no matter how far away the object is.
One formula connects object distance, image distance, and focal length for any mirror, as long as you get the plus and minus signs right.
Light bends when it crosses into a different transparent medium: that's why a straw looks broken in a glass of water.
Light bends twice going through a glass slab, once in and once out, and the two bends exactly cancel each other's angle, just shifting the ray sideways.
Refractive index is just a number that tells you how much a medium slows light down compared to air: a bigger number means a bigger bend.
A convex lens (thick in the middle) pulls light rays together; a concave lens (thin in the middle) spreads them apart.
A convex lens behaves a lot like a concave mirror: far objects give small real images, and only up close does it act as a magnifying glass.
A concave lens never changes its mind: the image is always virtual, erect, and smaller than the object, wherever you place the object.
The lens formula looks almost like the mirror formula, but with a minus sign: a small difference that's easy to mix up in exams.
A lens's 'power' is just 1 divided by its focal length in metres: a short focal length means a strong, high-power lens.
Chapter 10 · The Human Eye and the Colourful World
Your eye is a camera made of living tissue: here's what each part actually does.
How your eye lens changes shape to focus on things both near and far, and why it has limits.
Your eye focuses distant objects in front of the retina instead of on it, so far things blur, near things stay sharp.
Your eye focuses nearby objects behind the retina, so close-up things blur while distant ones stay clear.
As the eye ages, its power of accommodation fades, and many people then need bifocal lenses.
Unlike a glass slab, a prism's slanted faces bend light sideways: that sideways bend is the angle of deviation.
White light isn't one colour: a prism splits it into seven, because each colour bends by a different amount.
Stars twinkle because Earth's shifting atmosphere keeps bending their light by tiny, changing amounts.
You see the sun about 2 minutes before it actually rises, and 2 minutes after it actually sets: atmospheric refraction again.
Air molecules scatter blue light far more than red light: that scattered blue is what fills the daytime sky.
Chapter 11 · Electricity
Electric current is just the rate at which charge flows through a wire: measured in amperes, and only possible in a closed loop.
Charge doesn't flow on its own: it needs a push, called potential difference, the same way water needs a height difference to flow.
Every circuit component, cell, switch, bulb, resistor, meter, has a standard symbol, so a circuit diagram means the same thing to everyone who reads it.
The potential difference across a conductor is directly proportional to the current through it, and that constant ratio is its resistance.
A resistor's resistance depends on three things: how long it is, how thick it is, and what it's made of.
Join resistors end to end and the same current flows through all of them, while their resistances simply add up.
Connect resistors between the same two points and each gets the full voltage, while the total current splits between them.
Push current through a resistor and some (or all) of the electrical energy turns into heat: Joule's law explains exactly how much.
Electric power is the rate at which electrical energy is used or converted: measured in watts, and billed to your home in kilowatt-hours.
Chapter 12 · Magnetic Effects of Electric Current
A magnetic field is the invisible region around a magnet where its force can be detected, and field lines are how we draw it.
Any current-carrying wire is surrounded by a magnetic field of concentric circles, and the right-hand thumb rule tells you which way it curls.
Bend a straight wire into a loop, and its concentric circular fields overlap and straighten out into one uniform field at the centre.
A solenoid's magnetic field looks just like a bar magnet's, which is exactly why wrapping one around iron makes a switchable electromagnet.
A current-carrying wire placed in a magnetic field feels a real push, and Fleming's left-hand rule tells you exactly which way.
Every home runs on live, neutral and earth wires wired in parallel, with a fuse standing by to break the circuit if anything goes wrong.