Physics Practice

A circuit is a complete loop — like a circular track that electrons run around. Break the loop and everything stops.

A circuit diagram is like a map for electricity — it shows what's connected to what without drawing realistic pictures.

Some particles carry an invisible 'label' — positive or negative — that makes them push or pull on each other.

Current is like the flow rate of water in a pipe — how much charge passes a point each second.

Power tells you how quickly a device uses energy — a 100 W bulb converts energy twice as fast as a 50 W bulb.

Charge cannot pile up at a junction, and energy per unit charge must balance around a complete loop.

More push (voltage) means more flow (current). More resistance means less flow for the same push.

Like a river splitting into branches — the water (current) divides, but the pressure drop (voltage) across each branch is the same.

Resistance is like friction for electricity — a narrow pipe resists water flow more than a wide one.

Like cars on a single-lane road — every car (charge) must pass through every toll booth (component) in order.

Voltage is like water pressure — it's the 'push' that drives current through a circuit.

Touch a hot pan — heat flows from the pan to your hand through direct contact.

Energy is like money—you can spend it, save it, or change its form, but you can't make more out of nothing.

Hot air rises and cool air sinks — this circulation carries heat through the room.

What fraction of the energy you put in actually goes where you want it to go, rather than being wasted as heat.

A stretched rubber band 'wants' to snap back—that desire is stored energy.

The 'currency' that makes things happen. It's what you need to move, heat, or change anything.

The higher you lift something, the more energy it stores (ready to fall).

Heat always flows from hot to cold on its own — reversing this requires external work.

The faster something moves and the heavier it is, the more kinetic energy it has.

The combined 'useful' energy for mechanical motion — kinetic plus all forms of potential energy.

Energy waiting to be released—like a stretched rubber band or a ball held high.

How fast you use or produce energy. A powerful engine does work quickly.

The sun warms you even through the vacuum of space — that's radiation.

A spring or pendulum that bounces back and forth in a smooth, repeating pattern.

How 'hot' or 'cold' something is—how fast its molecules are moving on average.

The energy of jiggling atoms and molecules—what we experience as temperature.

Energy transferred by pushing something through space — force and displacement must both be present.

The total work done on an object is exactly what changes its kinetic energy.

Like gravity between masses, but for charges. Double the distance and the force drops to one quarter. Double either charge and the force doubles.

Every charge creates an invisible 'force zone' around it. Another charge entering this zone feels a push or pull without touching anything.

Run current through a loop between magnets and it spins — the magnetic force on each side of the loop pushes in opposite directions, creating rotation.

Electric potential is like altitude on a hill — charges 'roll downhill' from high potential to low potential, just as balls roll from high ground to low ground.

Push a magnet into a coil and current flows — the changing magnetic field 'induces' electricity. Pull it out and current flows the other way.

The faster you change the magnetic field through a loop, the bigger the voltage you get. Faraday's law tells you exactly how much.

Spin a loop of wire between magnets and you get electricity — the changing flux induces a voltage that drives current through an external circuit.

Nature resists change — when you push a magnet into a coil, the coil creates its own magnetic field that pushes back.

Moving charges create a swirling force field around them. This field can push on other moving charges or magnets.

A moving charge in a magnetic field feels a sideways push — perpendicular to both its motion and the field. It's like a cross-wind deflecting a moving ball.

Potential difference is the 'height drop' that makes charges flow — the bigger the drop, the harder the push.

A transformer trades voltage for current (or vice versa) — like a gear system trades speed for torque.

A fluid pushes up exactly as much as the displaced fluid would weigh.

Water pushes up more on the bottom of an object than on the top, so the object feels an upward lift.

Density tells you how tightly matter is packed. Heavy for its size means high density.

If you squeeze a gas, heat it, or add more particles, the other gas properties must adjust in a predictable way.

Pressure is how concentrated a force is. The same force on a smaller area creates more pressure.

Some substances warm up quickly, while others need much more energy for the same temperature change.

When two objects stop getting warmer or cooler because they have matched temperatures, they are in thermal equilibrium.

A spinning skater pulling their arms in spins faster — they're conserving angular momentum.

The force that pulls you toward the center when you go around a curve.

During a crash or bounce, forces act briefly but strongly, so motion can change a lot.

Momentum can move between objects but can't be created or destroyed.

Billiard balls bouncing off each other: the total energy stays the same, nothing is lost to heat or deformation.

All forces cancel out — the object doesn't accelerate, though it may still be moving at constant velocity.

Anything that makes something move, stop, speed up, slow down, or change direction.

A simplified picture that shows every push and pull acting on one isolated object.

The resistance you feel when sliding something across a rough surface — it always acts opposite to motion.

Everything pulls on everything else—but only huge things (like Earth) pull noticeably.

A big push for a short time or a small push for a long time can have the same effect.

Two cars crashing and sticking together: they move as one object and kinetic energy is lost.

Heavy things are stubborn—hard to start moving, hard to stop.

Once something is moving, friction resists its motion — less than static friction, but still present.

How 'heavy' something feels when you try to push it, regardless of gravity.

How hard it is to stop something moving. Heavy and fast = lots of momentum.

What you get when you add up all pushes and pulls, accounting for direction.

Things keep doing what they're doing unless something pushes or pulls them.

Push harder and you get faster acceleration; heavier object means slower acceleration for the same push.

When you push something, it pushes back on you just as hard.

The floor pushing up on you so you don't fall through — it acts at a right angle to whatever surface the object touches.

A pulley can make lifting easier by sharing the load between several rope segments.

If the clockwise and counterclockwise twists balance, the object will not start spinning faster one way or the other.

Stretch a spring twice as far, it pulls back with exactly twice as much force.

It takes more force to get something moving than to keep it moving.

If something is not speeding up, slowing down, or rotating more, the pushes and twists must balance.

The 'tightness' you feel in a rope when both ends are being pulled in opposite directions.

How hard you're twisting something. Depends on force AND distance from pivot.

How hard gravity pulls you toward the ground — it changes on different planets.

It is the launch speed needed so gravity cannot pull the object back forever.

A planet creates an invisible pull around it. The closer you are, the stronger that pull is.

An orbit is like falling around a planet instead of straight down onto it.

A large unstable nucleus can split apart and release a huge amount of energy.

Small nuclei can combine and release energy, especially inside stars.

Light can hit a surface like tiny packets of energy and knock electrons out.

Some nuclei are unstable and naturally break down over time.

At everyday speeds, classical physics works well. At speeds close to light, time and space behave differently from common intuition.

How quickly your speed (or direction) is changing. The 'push back' you feel when a car speeds up.

How fast something is spinning — a car wheel spinning fast has high angular velocity.

It tells you how fast the trip was overall, not how fast you moved at each moment.

A car on a circular track at constant speed is still accelerating—toward the center.

How far you are from where you started, in a straight line. Not the path you took.

A dropped ball accelerates at the same rate regardless of its mass.

It is what a speedometer shows right now, not over the whole trip.

Where something is, described by numbers from some starting point.

A thrown ball follows a curved path—horizontal motion is steady, vertical is accelerated.

Are you 'moving' on a train? Depends on whether you ask someone on the train or the platform.

How fast something seems to move depends on who is watching.

How fast you're going, ignoring which way—just the magnitude of motion.

An arrow pointing somewhere with a certain length—the length is 'how much,' the direction is 'which way.'

How fast something is moving AND which way it's heading—direction is essential.

Your eye or a screen sees an image based on where the outgoing rays meet or appear to meet.

A lens bends light on purpose so an image can be focused or spread out.

A mirror sends light back in a predictable way, so your eye traces the rays and sees an image.

A polarizing filter only lets through certain vibration directions.

Instead of tracing every ray of light, you trace only the key rays that tell you where the image must be.

When light is stretched, it shifts toward the red end of the spectrum.

Light moves incredibly fast, but not infinitely fast.

At a steep enough angle, light gets trapped and bounces inside the material.

Visible light is just the slice of electromagnetic waves our eyes happen to notice.

How 'tall' the wave is measured from the center line — bigger amplitude carries more energy and produces stronger effects.

Waves 'bend around corners'—you can hear someone even if you can't see them.

An ambulance siren sounds higher-pitched approaching, lower-pitched receding.

A 'rainbow' that extends far beyond visible light in both directions.

Light, radio, X-rays—all are EM waves, just different frequencies.

How many times something vibrates per second—high frequency means very rapid vibration.

A string or air column can vibrate in several allowed patterns, each with its own frequency.

Intensity tells you how concentrated the wave's energy flow is.

When waves meet, they add up or cancel out at each point depending on whether their crests and troughs align.

A slinky pushed back and forth: compressions and stretches travel along it.

Bigger wave amplitude usually sounds louder.

How long it takes a swing to go all the way and come back to where it started.

Higher frequency sounds are heard as higher pitch.

Instead of crests and troughs, the medium gets squeezed and spread out as the wave passes.

Like a ball bouncing off a wall—the wave reverses direction at the boundary.

A straw looks bent in a glass of water because light bends at the surface.

Push at just the right rhythm and the vibration builds up much more than usual.

Vibrating air that your ears detect. No medium, no sound (space is silent).

Sound moves faster in some materials than in others because the medium's particles pass the disturbance along differently.

The pattern looks frozen, with points that never move and others that vibrate the most.

Shake a rope side-to-side: the wave travels along the rope, but the rope moves up and down.

How fast the wave's shape moves forward through whatever it's traveling in.

How 'long' one complete wave cycle is — the spatial size of a single repeating pattern.

Energy traveling through something—like ripples on water. The water stays put; the ripple moves.