Internal resistance proportional to current?

In summary, The terminal voltage and current are measured as the resistance is decreased through a cell with emf and internal resistance. A graph of V (y axis) and I (x axis) shows a straight line with decreasing gradient. The terminal voltage decreases as the current increases due to the voltage dropped across the internal resistance, which increases with the current. This results in a continuous drop of voltage towards the internal resistance, with 1 Ohm causing a 1 Volt drop for every Amp of current.
  • #1
CAH
48
0
The terminal voltage and current are measured as the resistance is decresed through a cell with emf and internal resistance. Graph of V (y axis) I (x axis) shows straight line decreasing gradient.
1. Explain why terminal pd decreases as the current increases.

is terminal pd the same as pd/voltage? I thought the pd across a resistor would always be the same provided your not adding resistors. However the mark scheme says:

mention of pd across internal resistance or loss in internal resistance or emf>V,
pd across internal resistance/loss volts increases with current or correct use of equation to demonstrate

So does the internal resistance increase with the current and so voltage is lost through wires?

Thanks :smile:
 
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  • #2
No. As with all resistances, the voltage dropped across it is proportional to the current and the internal resistance is usually assumed to be constant. That is a bit of an oversimplification for many components, though.
 
  • #3
so the voltage will continuously drop to internal resistance? It seems like a lot of volts lost just to internal resistance?
 
  • #4
CAH said:
so the voltage will continuously drop to internal resistance? It seems like a lot of volts lost just to internal resistance?
IF the internal resistance is 1 Ohm then every Amp will cause a drop of 1 Volt. There's no surprise there.
 

1. What is internal resistance proportional to current?

Internal resistance proportional to current refers to the relationship between the resistance within a circuit and the amount of current flowing through it. This means that as the current increases, the internal resistance also increases in proportion.

2. Why does internal resistance increase with current?

This is due to the physical properties of the materials used in the circuit. As the current increases, the materials experience more collisions between particles, leading to an increase in resistance.

3. How does internal resistance affect circuit performance?

Internal resistance can cause a voltage drop within the circuit, leading to a decrease in the overall performance of the circuit. It can also cause the circuit to heat up and potentially damage components.

4. Can internal resistance be reduced?

Yes, internal resistance can be reduced by using materials with lower resistance, such as copper instead of steel. It can also be reduced by using thicker wires or increasing the surface area of the conductors.

5. How is internal resistance measured?

Internal resistance is typically measured using a multimeter. By measuring the voltage and current at different points in the circuit, the internal resistance can be calculated using Ohm's law (R = V/I).

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