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1. Okay, I feel like I'm being really stupid, but I've just completely lost the ability to find the current in a circuit.

The question is:
In a circuit of total e.m.f 4.5V, and 2 resistors of 68 Ohms and 12 Ohms, calculate the current in th2 12 Ohm resistor.

I know I = V/R and everything, but is the V the total e.m.f? And is the resistance the total resistance or just the resistance of the 12 Ohm resistor?

If anyone can help, it would be much appreciated.

Thanks!
2. (Original post by lucy_henley)
Okay, I feel like I'm being really stupid, but I've just completely lost the ability to find the current in a circuit.

The question is:
In a circuit of total e.m.f 4.5V, and 2 resistors of 68 Ohms and 12 Ohms, calculate the current in th2 12 Ohm resistor.

I know I = V/R and everything, but is the V the total e.m.f? And is the resistance the total resistance or just the resistance of the 12 Ohm resistor?

If anyone can help, it would be much appreciated.

Thanks!
It depends on whether the circuit is in series or parallel.
3. (Original post by lucy_henley)
Okay, I feel like I'm being really stupid, but I've just completely lost the ability to find the current in a circuit.

The question is:
In a circuit of total e.m.f 4.5V, and 2 resistors of 68 Ohms and 12 Ohms, calculate the current in th2 12 Ohm resistor.

I know I = V/R and everything, but is the V the total e.m.f? And is the resistance the total resistance or just the resistance of the 12 Ohm resistor?

If anyone can help, it would be much appreciated.

Thanks!
Has it told you anything about the internal resistance (r)? Or has it only given you the load resistance (R)?

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4. It's a series circuit, and there's negligible internal resistance, only the external resistors
5. (Original post by lucy_henley)
It's a series circuit, and there's negligible internal resistance, only the external resistors
In series current is constant.
6. I = V/R

For a circuit, to find Is (the source current) you'll want to use the source voltage and the total equivalent resistance of the circuit. If there are other sources, IT = VT/RT (total current, voltage and equivalent resistances).

For a series circuit, Rt (total resistance) = R1 + R2 + R3...

For a series circuit, voltage (potential differences) are shared between components, but the current is the same. For a parallel circuit the opposite is true - The voltage is the same for each parallel loop and the current is shared between components across other loops.

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