List of Common Misconceptions
From MrReid.org Wiki
This page is based on research by the Comprehensive Conceptual Curriculum for Physics Project.
- 1 General
- 2 Atoms
- 3 Electricity
- 4 Energy
- 5 Fields
- 6 Forces
- 7 Gravity
- 8 Magnetism
- 9 Motion
- 10 Relativity
- 11 Space
- 12 Waves
- 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.
- 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".
- 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 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.
- 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.
- Spacecraft travel in straight lines.
- Jets can fly in space.
- Rockets require something (e.g. air) to push against.
- 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.
- Light is either a wave or a particle.
- Particles cannot have wave properties and vice versa.
- All photons have the same energy.