MIdterm physics

• Magnetism


  The ability of a material to attract iron, steel, and its alloys
• Electromotive force is not a force
• Voltage


  The electric pressure that causes current flow
• Power in a resistor


  • The rate of change of electrical energy to thermal energy
• Magnetic field lines

  • Visualize magnetic field and its interaction with magnetic materials
  • Representation of north and south magnetic poles
• Like charges


  • Repulse
  • Unlike charges attract
• Heat disrupts magnetic domains by making molecules vibrate and break out from their ordered patterns
• All energy conversion obeys the law of conservation of energy
• Creation of voltage


  • Techniques involving the production of excess electrons at one terminal and a deficiency of electrons at another terminal
  • Current through a resistor
  • Devices like electric generator, electric cell, thermocouples, crystals, and solar cells
• Power in circuit analysis


  The rate of conversion of energy from one form to another
• Magnetic field


  A region of space around a moving charge or magnet where magnetic force acts on magnetic material
• Magnetic Induction is the act of becoming magnetized, which certain substances perform when placed in a magnet
• If a magnet is cut, each piece will have its north and south magnetic poles; magnets can be destroyed by heating or constant hitting
• Voltage


  • Similar to the pressure of water at different heights
  • Potential difference is potential energy divided by charge
  • Symbol is V, unit is joule per coulomb (volt, V)
• Power in dry cells


  • The rate of conversion of chemical energy to electrical energy
• Power in Mechanics


  The rate of doing work, how fast work is done
• Voltage


  Energy/charge or V= W/q
• Magnetic monopole does not exist
• Magnetic properties are due to moving charges; a stationary charge does not exhibit a magnetic property
• Like charges repels, unlike charges attract
• Lenz’s Law states that the current induced in a circuit due to a change in a magnetic field is directed to oppose the change in flux and to exert a mechanical force that opposes the motion
• Magnetic Induction


  The act of becoming magnetized, which certain substances perform when they are placed in a magnetic field
• Faraday’s Law of Magnetic Induction expresses that a changing magnetic field induces a voltage in a circuit, developed based on experimental observations made in 1831 by Michael Faraday
• Place it near in conducting coil or wire = Magnetized
• Heat + Hit = Demagnetized
• Lenz’s Law vs. Faraday’s Law


  Lenz's law states the direction of an induced current, and Faraday's law relates the magnitude of the induced back EMF to the rate of change in the inducing magnetic field
• Electromagnetic waves are a form of radiation that travels through the universe, formed when an electric field couples with a magnetic field
• Plane mirror


  • One with a flat surface, used to see the exact image of oneself
• There are two types of mirrors: plane mirror and spherical mirror
• Concave mirrors

  • Shaving mirrors, makeup mirrors, dentist's mirrors
• Convex mirror


  Bulges outward to the incident rays
• Concave mirror

  Curves inward in the direction of the incident rays
• Plain Mirror Images: A real image is formed by actual intersection of reflected rays, while a virtual image is formed behind the mirror and is upright relative to the object
• Magnetic field

  The region near a magnet, or near a conductor conveying an electric current
• Convex mirrors


  • Shiny Christmas ball, rearview mirrors of cars, dome mirrors in supermarkets
• With hand rule: thumb points in the direction of the current; fingers point in the direction of the magnetic field
• Magnetic domains rearrangement


  Vibrate and break out from their ordered patterns, resulting in the rearrangement of the magnetic domains
• Spherical mirror


  • Has a reflecting surface taken from the surface of a sphere, may be concave or convex
• Mirrors


  A mirror is any surface that is smooth enough to produce a regular reflection of light incident upon it
• The image may also be larger than, the same size as, or smaller than the object