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# Thevenin equivalent circuit watch

1. I'm not sure what the overlapping circles symbol means. Any help with the question would be appreciated
2. (Original post by blah3210)

I'm not sure what the overlapping circles symbol means. Any help with the question would be appreciated
It is a current source producing a current of 1 mA
3. (Original post by blah3210)

I'm not sure what the overlapping circles symbol means. Any help with the question would be appreciated
(Original post by crashMATHS)
It is a current source producing a current of 1 mA
To be fully accurate, it's a 'constant current' source, meaning it produces the same current whatever the load.
4. (Original post by blah3210)

I'm not sure what the overlapping circles symbol means. Any help with the question would be appreciated
1. As stated the symbol is a constant current source.

2. Thevenin's theorem says that any circuit comprising only voltage sources, current sources, and resistances can be replaced with an equivalent circuit comprising a single voltage source in series with a single resistance . It is equivalent in the sense that it behaves identically to the original circuit as far as a load resistance is concerned.

3. To find for a specific circuit, find the open circuit voltage of the circuit across the output via Kirchhoff's laws/Ohm's law - this is

4. To find for a specific circuit:

a) replace each voltage source with its internal resistance (0 for ideal voltage sources i.e short out ideal voltage sources)

b) replace each current source with its internal resistance (infinite for ideal current sources i.e. make ideal current sources open circuit)

and compute the resistance of this modified circuit across the output terminals - this is

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