SIMPLE CIRCUITS

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SIMPLE CIRCUITS

• E. M. F. and Voltage
• Current
• Ohms Law
• Resistors in series
• Resistors in parallel

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e.m.f. and p.d. (1)
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e.m.f. and p.d. (2)
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e.m.f. and p.d. (3)
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Voltmeter

• Measure e.m.f. and p.d. across the device
• It must be connected in parallel with the device

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Current and charge

• Current is the rate of flow of charge
• I Q/t
• unit ampere (A)
• direction of conventional current is just the
  opposite of the direction of flow of electrons

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Ammeter

• Measure the current through the circuit
• It must be connected in series with other devices

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Conservation of charge

• Current in current out
• different points have the same current in the
  simple circuit

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Ohms law

• V ? I
• or V IR
• or R V/I
• unit ohm (?)
• There are ohmic and non-ohmic substances

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Resistance and dimensions of a wire

• R ? l/A

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Resistors in series

• Equivalent resistance R R1 R2

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Resistors in parallel

• Equivalent resistance R

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Measurement of resistance (1)

• Rv gtgt R

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Measurement of resistance (2)

• R gtgt RA

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The End