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Key ideas in physics common mistakes
Study Key ideas in physics with curriculum-aligned Common Mistakes resources, practice links, and exam-focused support.
At a glance
common mistakes
Resource type
Topic
Key ideas in physics
Common mistakes
Energy is used up
Saying energy is used up.
Fix itSay energy is transferred, stored or dissipated; conservation still applies.
Current and potential difference are the same
Treating current as the same quantity as potential difference.
Fix itCurrent is rate of flow of charge; potential difference is energy transferred per charge.
Mass and weight mean the same thing
Using mass and weight interchangeably.
Fix itMass is measured in kg; weight is a force in N caused by a gravitational field.
Speed and velocity are identical
Ignoring direction when discussing velocity.
Fix itSpeed is scalar; velocity includes direction.
Reflection and refraction are interchangeable
Describing bending at a boundary as reflection.
Fix itReflection is bouncing back; refraction is changing direction because speed changes at a boundary.
A generator is just a motor
Confusing the motor effect with electromagnetic induction.
Fix itMotors use current in a magnetic field to produce force; generators induce potential difference from motion.
Red shift is the Big Bang
Calling red shift the Big Bang theory.
Fix itRed shift is evidence for expansion; the Big Bang is the explanatory model.
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