List of Common Misconceptions

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This page is based on research by the Comprehensive Conceptual Curriculum for Physics Project.


  • History is irrelevant in science


  • There is only one correct model of the atom.
  • Electrons orbit the nucleus like planets around the Sun.
  • Hydrogen is a typical atom.
  • Electrons are physically larger than protons.


  • Positive and negative are absolute, not arbitrary.
  • High voltage by itself is dangerous.
  • Voltage is the same as energy.
  • Capacitors and batteries operate on the same principle.
  • No potential difference exists in between the plates of a capacitor, only on the plates themselves.
  • There is a net charge on a capacitor.
  • Resistors consume charge.
  • Electrons move around a circuit at the speed of light.
  • A conductor has no resistance.
  • Current gets used up as it flows around a circuit.

Alternating Current

  • Charges move all the way around a circuit and all the way back.
  • Energy is not lost in a transformer.
  • Electrical companies supply electrons.


  • Energy is "used up", "runs out" or can be "destroyed".
  • Something not moving has no energy.
  • Energy can be recycled.
  • Energy is a force.
  • When an object is released all its gravitational potential energy is instantly converted to kinetic energy.


  • A cold body contains no heat.
  • There is no limit on the lowest temperature.
  • An object has no mass at absolute zero.
  • A coat or jumper actually makes you warmer.
  • Heat and cold can flow like liquids.
  • Heat and temperature are the same thing.


  • Field lines are real.
  • Field lines can begin and end anywhere.
  • There are a limited number of field lines.
  • Field lines only exist in two dimensions.
  • A moving charge accelerates along a field line.


  • All forces must be contact forces.
  • A force is required to maintain constant velocity; all objects will eventually come to a halt if the force is removed.
  • Action-reaction pairs act on the same body.
  • Acceleration causes a force (rather than vice versa).
  • Friction cannot act in the direction of motion.
  • Equilibrium is a consequence of Newton's Third Law.
  • Only living things (e.g. people, animals) exert forces. Inanimate things (e.g. tables, floors) do not.
  • A force applied by one object to another (e.g. a hand to a ball) still acts on the object once contact ceases (e.g. after the ball leaves the hand).

Fundamental Forces and Interactions

  • The gravitational force is the strongest.
  • Electricity and magnetism are two different forces.
  • All forces are equally effective over all ranges.
  • None of the fundamental forces have been proven to exist.


  • Gravity does not exist in a vacuum (i.e. it is a property of matter) or does not exist in space.
  • Without gravity, all objects are equally easy to move.
  • Weightlessness means that there is no gravity.
  • Gravity on Earth is caused by the spinning of the Earth.
  • The sudden removal of a gravitational field would cause objects to float "upwards".

Falling Objects

  • Heavier objects fall faster than light objects.
  • Heavier objects accelerate faster than light objects.
  • Gravity only acts on an object when it is falling.


  • The Moon is not falling; or is not in free fall.
  • The force acting on the Moon is somehow different to the force acting on a falling apple.
  • There are no gravitational forces acting on an object in orbit (e.g. the Space Shuttle).
  • Planetary orbits are circular.
  • The speed of a planet in orbit is constant.
  • Some object must be at both foci of an elliptical orbit.
  • All planets orbit at the same speed.
  • All planets orbit in exactly the same plane.


  • North and South poles are the same as positive and negative charges.
  • Magnetic field lines begin and end at magnetic poles.
  • Magnetic poles can be isolated.
  • Magnetic fields are two-dimensional.
  • A released charge will drift towards a magnetic pole.


Speed and Acceleration

  • Two objects side-by-side have the same speed.
  • Acceleration and velocity are always in the same direction.
  • Velocity is a force.
  • If velocity is zero, acceleration is zero.


  • Conservation of momentum only applies in collisions.
  • Momentum is the same as force.
  • Momentum is the same as kinetic energy.

Circular Motion

  • Circular motion does not require a force.
  • Centrifugal forces are real forces.
  • An object moving in a circle at constant speed is also at constant velocity; i.e. experiences no acceleration.
  • An object moving in a circle will continue to move in a circle when released; or will fly out radially.

Harmonic Motion

  • Period of oscillation depends on amplitude.
  • The heavier the pendulum bob, the faster the oscillation.


  • Time is absolute.
  • Length and time only change for one observer.
  • Time dilation refers to two different clocks in two different frames.
  • Relativity is theoretical and is not supported by experimental evidence.
  • There exists a "preferred" reference frame for the Universe.
  • A mass moving at the speed of light becomes energy.


Navigating in Space

  • Spacecraft travel in straight lines.
  • Jets can fly in space.
  • Rockets require something (e.g. air) to push against.

Black Holes

  • Black holes are big.
  • Light always travels in straight lines.
  • If the Sun became a black hole Earth would be destroyed; black holes exert larger forces than their parent stars.
  • Objects in space make sounds.


  • Waves transfer matter.
  • All waves require a medium.
  • Waves do not have energy.
  • Different colours are different types of waves.


  • Light has no origin.
  • Light is a mixture of waves and particles.
  • The speed of light never changes.
  • Light and matter do not interact.
  • Refraction is the bending of waves.

Wave-Particle Duality

  • Light is either a wave or a particle.
  • Particles cannot have wave properties and vice versa.
  • All photons have the same energy.