cset electr and magnets

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cset electr and magnets
2015-09-18 22:14:45

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  1. Describe and provide examples of electrostatic and magnetostatic phenomena

    • friction from rubbing a balloon against
    • hair draws electrons from the hair onto the surface of the balloons because the material of the balloon has a greater affinity for electrons than the hair does 

    shock - spark of static electricity caused by a sudden electrostatic discharge
  2. Predict charges or poles based on attraction/repulsion observations
    • Objects that are strongly magnetic are called ferromagnetic. They may
    • either be hard (which doesn't lost its magnetism after being magnetized
    • easily; or soft, which does lost its magnetism after being magnetized).
    • When an object is magnetized, all the dipoles (molecular magnets) become
    • aligned. A magnet's pole is a point in a magnet at which it's magnetic
    • force is concentrated. The two poles, north and south pole, point to
    • it's magnetic pole, south or north magnetic pole. The first law of
    • magnetism states that like poles repel and that unlike poles attract.
  3. Build a simple compass and use it to determine direction of magnetic fields, including the Earth’s magnetic field
    lay a magnetized sewing needle on a thin slice of cork and let the cork float in a glass of water 

    magnetize sewing needle by stroking it along a magnet about 50 times in the same direction

    needle will point towards north 

    compass shows the direction of magnetic field
  4. Relate electric currents to magnetic fields and describe the application
    of these relationships, such as in electromagnets, electric current
    generators, motors, and transformers
    • Electric current is the rate of flow of electric charge
    • (electrons). In a magnetic force, the force between two moving charges
    • can be electric currents.Electromagnetics have
    • several applications, all of which attract metals when they are
    • switched on. They convert electric energy to mechanical energy.On the other hand, electric current generators produce electric current from mechanical energy.Electric motors uses
    • the Lorentz force (a current-carrying wire that goes through a magnetic
    • field which can produce movement) to transform electrical energy into
    • mechanical energy.A transformer consist
    • of two coils of wire that is wound onto the same core of soft
    • ferromagnet (unable to retain its magnetism) material . A transformer is
    • used to change an alternating electromotive force in one of the coils
    • to a different electromotive force in the other coil. It can change the
    • values of voltage and current without changing the frequency. It
    • consists of a primary and secondary coil. The first coil in a transformer is connected to the AC voltage and is called the primary coil. The second coil is the one in which an AC voltage is induced and is called the secondary coil. Step-up transformer has a secondary coil that is greater, has more turns, than that in the primary coil. Increases voltage.Step-down transformer has a secondary coil that is less, fewer turns, than that in the primary coil. Reduces voltage.Turns ratio is the ratio of the number of turns in the secondary coil to the number of turns in the primary coil.
  5. Design and interpret simple series and parallel circuits
    • simple series circuit:
    • wires through which electrical charge flows
    • a battery or power supply to provide the voltage to push charge around the circuit 
    • a switch to interrupt the current a resistor 
    • a light bulb which works when the current flows through it 
    • connected in a simple loop 

    • parallel circuits:
    • the electrical current flows in two or more closed paths simultaneously 
    • two branches of circuit are independent
    • if one component fails, the rest do not work 
    • as components are added, the resistance in the circuit increases and the current through the circuit is reduced 

    as components are added, more energy is drawn from the power supply
  6. Define and calculate power, voltage differences, current, and resistance in simple circuits
    • Power is the force motivating electrons to flow, called voltage.
    • It is the measurement of potential energy that is relative between two
    • points. Voltage is measured in volts. To solve for the voltage (E), you
    • multiply current (I) times resistance (R). E=I x RCurrent is the continuous movement of electrons in a circuit.Resistance is the opposition to motion. Resistors are important otherwise too many electrons will move through the circuit.


    current: the sum of the current in each loop of a multi-loop circuit must add up to the total