QA4

• What do magnets produce?

  A magnetic field
• Who is credited with early descriptions of magnetism?

  Thales of Miletus
• Where were the first known magnetic materials found?

  Magnesia, Turkey
• What is the key feature of permanent magnets?

  They create their own magnetic field continuously
• What materials are permanent magnets made of?

  Ferromagnetic materials
• What is magnetite composed of?

  Iron oxide (Fe3O4)
• What is the shape of a horseshoe magnet?

  U-shaped
• How do opposite poles of magnets interact?

  They attract each other
• What are iron fillings used for?

  Visualizing magnetic fields
• How does Earth act like a giant magnet?

  It generates a magnetic field extending into space
• Who discovered electromagnetic induction?

  Michael Faraday
• What does Faraday's Law of Electromagnetic Induction state?

  Induced EMF is proportional to magnetic flux change
• What is the equation for induced EMF?

  EMF = Bℓv
• What happens when a conductor moves through a magnetic field?

  Charges experience a magnetic force
• What is the angle that induces the greatest current?

  90 degrees
• What does optics study?

  Behavior and properties of light
• What does Huygens' Principle state about light?

  Light behaves as a wave
• Who proposed the particle theory of light?

  Isaac Newton
• What is the photoelectric effect?

  Light ejects electrons from a metal surface
• What is the minimum energy required to remove an electron called?

  Threshold energy
• What is the law of reflection?

  Angle of incidence equals angle of reflection
• What are electromagnetic waves composed of?

  Oscillating electric and magnetic fields
• What is the speed of electromagnetic waves in a vacuum?

  3.0 × 10⁸ m/s
• What is the relationship between frequency and energy of EM waves?

  Higher frequency means higher energy
• What are some applications of radio waves?

  Broadcasting and satellites
• What is the purpose of microwaves?

  Cooking and GPS
• What is the electromagnetic spectrum based on?

  Wavelength and frequency
• What is the difference between regular and diffuse reflection?

  Regular reflection forms clear images
• How does the photoelectric effect support the particle theory of light?

  It shows light ejects electrons as particles
• What is the angle of incidence in relation to the normal line?

  It is the angle between the incident ray and normal
• What is the normal line in a ray diagram?

  An imaginary line perpendicular to the surface
• What does Snell's Law describe?

  Change in direction of light between media
• What is the relationship between the number of turns of the coil and current?

  Directly proportional
• What happens to the magnetic field strength when the distance increases?

  It decreases
• What is the effect of increasing the motion of the magnet on current?

  It increases the current
• What is the significance of the angle of the magnetic field in inducing current?

  90 degrees induces the greatest current
• What is the relationship between the area of the coil and induced current?

  Increasing area increases current
• What is the role of the conductor's movement in generating EMF?

  It induces a potential difference
• What is the purpose of the photoemission process?

  To eject electrons from metal surfaces
• What is the significance of threshold frequency?

  Minimum frequency to eject electrons