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# PHYSICS ELECTRICITY CONFUSING!! infinite resistance?

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1. Consider a circuit
A cell supplying 1.5V connected in series with a 1.5k ohm resistor whose pd is 0.9V and a diode whose pd is 0.6v.
Now consider if you put the diode in reverse bias...
if you reverse the bias, the textbook says the diode has infinite resistance, I get that. The textbook also says that the circuit current would be 0.
I also get that. It is saying that the pd across the resistor will be 0- I get that because with no current can be no voltage?
But it is also saying that the pd across the diode, with infinite resistance, is now equal to the emf.
How can there be a pd when there is no current... I am thinking about the expt with a cell of internal resistance, when there is no current the terminal pd is equal to the emf but how can you have pd with no current???
2. The current is infinitely small, not 0. And the pd on the diode is very close to the cell emf but not equal to the cell emf
3. (Original post by Lawliettt)
The current is infinitely small, not 0. And the pd on the diode is very close to the cell emf but not equal to the cell emf

okay so is this because the diode has the majority share of the pd because 1.5kohm is incomparable to infinite resistance?
Also,
there is a q in my textbook how many baryons and mesons are there in an atom of Beryllium, atomic no 4, mass number 9
I know there are 9 baryons but I am wondering how many mesons there are... I am inclined to say 0, but we have learnt that the pi mesons are exchange particles of the strong nuclear force between protons and neutrons...
so there must be some mesons?
5 Baryons 4 Mesons
5 Baryons 0 Mesons
9 Baryons 4 Mesons
9 Baryons 0 Mesons

many thanks for ur help
4. (Original post by Lola1244)
okay so is this because the diode has the majority share of the pd because 1.5kohm is incomparable to infinite resistance?
Also,
there is a q in my textbook how many baryons and mesons are there in an atom of Beryllium, atomic no 4, mass number 9
I know there are 9 baryons but I am wondering how many mesons there are... I am inclined to say 0, but we have learnt that the pi mesons are exchange particles of the strong nuclear force between protons and neutrons...
so there must be some mesons?
5 Baryons 4 Mesons
5 Baryons 0 Mesons
9 Baryons 4 Mesons
9 Baryons 0 Mesons

many thanks for ur help
1. Yes. You're right. The diodes resistance is so high compared to any other resistance in the circuit that it's getting a big share of the pd.

2. haven't looked at unit 1 physics in a while but I'm not sure why there would be any mesons in a Berylium nucleus. It's just protons and neutrons. I think the answer is 9 baryona 0 mesons.

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Updated: April 16, 2016
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