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19 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Definition of potential difference |
Energy transferred per coulomb of charge |
Think of the equation: V = E/Q |
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Definition of Resistance |
The ratio of current to p.d. across a resistor |
Again, refer back to the equation: R = V/I |
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How many electrons in one Coulomb of charge? |
6.25 x 10^18 |
It's the reciprocal of the charge on one electron. You can also use Q = nq |
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Unit of charge |
Coulomb (C) |
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A s is another unit for... |
Coulomb, C (charge) |
Go back to the units and equations... Amps is for current, seconds is for time. What is found by current x time? |
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Definition of current |
Rate of flow of charge |
Think back to the equation: I = dQ / dt (d = change in) |
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For a fixed p.d. across it, if you double the resistance, the current... |
Halves |
Relate to the equation V = IR |
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What causes resistance of a component? |
Collisions between electrons and metal ions |
Think of the microscopic structure of what's going on |
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Units for resistance |
Ohms |
symbol is the Greek letter Omega |
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An alternative value for this unit is joules per coulomb, J C-1 |
Volt, V |
Relate to the equation. Joules are units for energy, Coulombs are unit for charge. ?? = energy / charge |
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Ohm's Law |
Current through a resistor is directly proportional to the p.d. across it, at a constant temperature |
R = V/I , so the resistance is fixed if the resistor follows Ohm's Law |
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Kirchoff's 1st Law |
"The total current entering a junction in a circuit is equal to the total current leaving it." IT = I1 + I2 + I3 ... |
This is a statement of the conservation of charge. |
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Kirchoff's 2nd Law |
The EMF across a power supply is equal to the p.d. across any loop in a parallel circuit VT = V1 = V2 = V3 ... |
This is a statement of conservation of energy. |
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Total resistance in a series circuit RT = |
RT = R1 + R2 + R3 ... |
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Total p.d in a series circuit VT = |
VT = V1 + V2 + V3 ... |
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Total conductance in a series circuit |
1/GT = 1/G1 + 1/G2 + 1/G3 ... |
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Total resistance in a parallel circuit |
1/RT = 1/R1 + 1/R2 + 1/R3 ... |
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Total conductance in a parallel circuit |
GT = G1 + G2 + G3 ... |
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Total current in a parallel circuit |
IT = I1 + I2 + I3 ... |
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