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# Physics PD and current question..? watch

1. the question is:
"for the circuit in figure 7, calculate the pd and the current for each resistor and diode."

we are meant to assume that the diode in the forward position has a voltage of 0.6v, im not even sure which one is in the forward position! please help! picture should be below :P

2. bump
3. really need some help with this!
4. (Original post by rub em out)
the question is:
"for the circuit in figure 7, calculate the pd and the current for each resistor and diode."

we are meant to assume that the diode in the forward position has a voltage of 0.6v, im not even sure which one is in the forward position! please help! picture should be below :P
The diode looks like an arrow, doesn't it? It lets current in the direction it's pointing, and stops in the opposite direction.

Try to determine the path of the current.

Then you will be able to calculate potential drops across each resistor and each diode. The diodes and resistors are in parallel to one another. This means that potential drop across the resistor and diode is the same in each couple.
5. Did you figure out how to do this in the end?Because now I'm stuck on the exact same question...
6. im stuck on this!
7. (Original post by rub em out)
the question is:
"for the circuit in figure 7, calculate the pd and the current for each resistor and diode."

we are meant to assume that the diode in the forward position has a voltage of 0.6v, im not even sure which one is in the forward position! please help! picture should be below :P

"assume that the diode in the forward position has a voltage of 0.6v"
Does the question actually state this? Or is it meant to be an "ideal" diode?
If the 0.6V is correct then firstly X is in the forward direction.
The conventional current flows in the direction the diode points.
In this circuit it flows clockwise and down through diode X.
If the pd across it is 0.6V then the pd across Q is also 0.6V as they are in parallel. So the pd across the other resistor (and diode) is 3 - 0.6V.
No current flows through the other diode as it is reverse biased. All the current in the circuit goes through P.
There is enough information above now to find the pd across and currents in the resistors by applying Ohm's Law.

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