Definition of internal resistance and how to obtain EMF and internal resistance from a graph AQA A level specification - post 2015 Music: TheFatRat - Unity
Hi, When the current increases both R's stay the same. However due to Kirchoffs laws and ohms law V=IR the PD the internal resistance had over it increases. This means that the PD to the other resistor (the rest of the circuit decreases) Over time in a real battery little r (internal resistance) will change, normally increase, and less PD will reach the main part of the circuit due to the internal resistance taking more PD in accordance with ohms law. Hope that helps
Ah, Depend what you are changing in the circuit. 1) If you have a set voltage you have to change the total resistance of the circuit to change the current. The only way you can do this is by changing the external resistance. To increase the current you will need to decrease the external resistance. This means the internal resistor will have a bigger share of the voltage than before due to V=IR (since internal resistor still follows this) 2) Another way to change current is change total Voltage. But this means r and R will get a proportional change (see potential dividers) IE double voltage will double current for ALL resistors, so each resistor will get double the PD across it. So it depends on the situation the current is changing under.
When current Increases does big R decrease but little R stay the same
Hi,
When the current increases both R's stay the same. However due to Kirchoffs laws and ohms law V=IR the PD the internal resistance had over it increases. This means that the PD to the other resistor (the rest of the circuit decreases)
Over time in a real battery little r (internal resistance) will change, normally increase, and less PD will reach the main part of the circuit due to the internal resistance taking more PD in accordance with ohms law.
Hope that helps
TLPhysics if current is increasing and the pd across little r increases cuz of V=IR why can the same not be said about big R
Ah,
Depend what you are changing in the circuit.
1) If you have a set voltage you have to change the total resistance of the circuit to change the current. The only way you can do this is by changing the external resistance.
To increase the current you will need to decrease the external resistance. This means the internal resistor will have a bigger share of the voltage than before due to V=IR (since internal resistor still follows this)
2) Another way to change current is change total Voltage. But this means r and R will get a proportional change (see potential dividers) IE double voltage will double current for ALL resistors, so each resistor will get double the PD across it.
So it depends on the situation the current is changing under.
TLPhysics thank you ..situation 1 is what I was thinking about because most of the time In exam questions it’s a set voltage