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Potential Difference (Voltage)

Potential Difference (Voltage). How does a battery work? . A build-up of electrons is one terminal of the battery (we call it the negative terminal). At the same time there are electrons leaving the other terminal which makes it more positive (this is the positive terminal).

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Potential Difference (Voltage)

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  1. Potential Difference (Voltage)

  2. How does a battery work? • A build-up of electrons is one terminal of the battery (we call it the negative terminal). • At the same time there are electrons leaving the other terminal which makes it more positive (this is the positive terminal). • The stored electrical charges in a battery is called electrical potential energy • If the battery is not hooked up to a circuit, the stored charges will remain stored.

  3. If the battery is connected to a circuit these electrons can now move from the negative end of the terminal to the positive end • This cannot happen until the circuit is closed. • In a closed circuit the electrons can do “work” - such as lighting a bulb, powering a kettle, etc.

  4. Potential Difference • We know that a battery has electrical potential energy. Energy is always measured in joules (J) • In a circuit, we compare charges at different point. • This comparison or difference in the charges at 2 different points in a circuit is called potential difference. • This means means the difference in potential energy per coulomb of charge at one point in the circuit compared to another point in the circuit.

  5. The units for potential difference is joules/coulomb. We call this a volt. • The unit for potential difference is volts and it can be measured using a voltmeter. • To find the potential difference by using the equation: V = E/Q. • So, if we know the amount of chemical energy (E) converted to electrical energy and we know the charge difference between the negative and positive terminals of the battery (Q) we can work out the potential difference (V)

  6. Example • If 150J of chemical energy is converted to electrical energy and this energy places 30C of negative charge at the negative terminal compared to the positive terminal, what is the potential difference between the terminals of the battery? • Formula: V = E/Q • We have: E = 150J, Q= 30C • V = 150J/30C • V = 5V

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