Electron and Electricity

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Electron and Electricity

• Electricity is the movement of electron thought a
  material.
• Electron flows along like a water current in a
  stream, so we call it Electric current.
• You need something to give energy to electrons.
  You need a battery and the power of it is called
  voltage.
• The higher the voltage, the more power there is
  to drive the electrons thought the circuit

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Electron and Electricity

• Voltage is like the Steepness of a river. The
  bigger the different in height between the start
  and the end of the river, the faster the water
  current will flow.
• Voltage is measured in Volts

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Electrical Resistance

• Materials such as copper or aluminium metals
  that conduct electricity are called conductors.
  Materials that don't allow electrons to pass
  through them, such as rubber and plastic, are
  called insulators.
• Resistance is a measure of How an object opposes
  the passage of electrons. The unit of electrical
  resistance is the ohm.

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Electrical Resistance

• Every materials has Resistance. Copper has a low
  resistance and the wood has a high resistance.
• For example, a meter of copper has only 1 Ohm
  but a meter of wood has 10000000 ohm
• We need resistance to reduce the flow of
  electrons thought a circuit, so we can build
  resistor to behave as Electrical resistance.

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Reading Resistor Values

• The resistance of resistors is indicated using
  colour-coded bands on the body of the resistor
• The first three coloured indicates the value of
  the resistor in Ohms. The first band tells us the
  first digit, the second band tell us the second
  digit and the third band tell us the number of
  zeros

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Color Code Table
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Examples

• A) If the first band is green (5) the second
  digit is blue (6) and the third band is orange
  (3), the value of the resistor is 56000 ohm.
• Because 1000 Ohm 1 K, we have 56k
• B) red, red, yellow. So we have 2, 2, 0000 or
  220.000 Ohm

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Exercises

• 1. What resistor values are indicated by the
  following colour bands?
• (A) red, black, red(B) grey, red, orange(C)
  orange, white, blue
• (D) green, white, black
• 2. What are the colour codes for the following
  resistance values?
• (A) 2.2k (B) 270 (C) 56 k
• 3. What are the maximum and minimum values of a
  resistor with the following colours
• Red, orange, brown with a gold tolerance band

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Ohms Law

• There is a relationship between Voltage, Current
  and resistance.
• The current in a circuit ( amp) is directly
  proportional to the applied potential difference
  (volts) and inversely proportional to the
  resistance of the circuit ( resistance).
• I v/r

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Ohms Law

• I v/r
• A nine volt battery supplies power to bulb with
  a resistance of 18 ohms. How much current is
  flowing through the bulb?
• Solution Substitute in the values for
  V(Voltage) and R(Resistance).

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Problem 1

• A 110 volt wall outlet supplies power to a Tv set
  with a resistance of 2200 ohms. How much current
  is flowing through the Tv?

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Problem 2

• A CD player with a resistance of 40 ohms has a
  current of 0.1 amps flowing through it. Calculate
  how many volts supply the CD player?
• Choose your answer below
• 10.0 volts
• 0.0025 volts
• 400.0 volts
• 4.0 volts

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Designing a resistor network

• Sometimes you need a kind of resistor, but you
  don't have it on hand and it doesn't exist.
  Fortunately, it's possible to use several
  different resistors in combination to get
  virtually any level of resistance, for example if
  you have 2 resistor of 20 Ohm and you need a
  resistor of 40 Ohm, just add both in serial , so
  Rt R1 R2 ( Serial )

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Designing a resistor network

• In the Figure you can see three resistors, but
  this time they're connected in parallel. Each
  electron will flow through one of the three
  resistors.
• This three resistor have a equivalent resistor of

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A Easier Serial Formula

• The formula is a bit
  difficult to remember, So could we find something
  easier?
• Yes, come on try on

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A Easier Serial Formula
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Electron and Electricity

• In this circuit, calculate
• A) the total resistance in the circuit?(B) the
  total current flowing at point A?

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Electron and Electricity

• This is a circuit the resistors are in parallel
• Calculate
• A) the total resistance in the circuit?(B) the
  total current flowing at point B and the current
  at C and D?

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Electron and Electricity

• In this circuit, calculate
• A) the total resistance in the circuit?(B) the
  total current flowing at point A?

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