# Diode

Discussion in 'General Electronics Chat' started by fahadatnet, Feb 6, 2005.

Dec 22, 2004
9
0
Hi to all.
I am in a state of confusion over a question.
The question is that if a diode is connected with a 5V battery & if a voltmeter is attached in parallel to both diode as well as battery then what will be the reading of voltmeter.
(a) 0 v
(B) 0.7v

If question is not clear then understand it this way:-
All three(diode,battery & voltmeter) are attached in parallel, what will voltmeter read?

Plz. clear my confusion.

2. ### Firestorm Senior Member

Jan 24, 2005
353
0
if everything is hooked up in parallel, then the answer should be 5v....this is due to the fact that parallel circuits have a constant voltage and series has constant current...i think this is right and hope it helps...thx l8er

-fire

3. ### vineethbs Well-Known Member

Nov 14, 2004
56
0
ya me too , i think its 5V ,) the diode will be fried , so it will be an open ckt .
)
the potential across an ideal voltage source wud not vary so it shud be 5V.
(thats the real reason , assuming the diode can take any current )
another question , what if we put two voltage sources , say v1 and v2 in parallel ?

4. ### beenthere Retired Moderator

Apr 20, 2004
15,815
282
Hi,

Ignoring the meter, the diode will be in a series circuit with the battery - there's no other element to share current with. If the diode is foreward biased, the measured voltage across it will be about .7 volts. That assumes that the battery is really cruddy, and won't supply enough current to fry the junction. Turned the other way, the diode will have 5 volts across it, as it will be reverse biased, and will not be conducting. Placing a couple hundred ohm resistor in the series circuit makes things a bit more realistic. That will hold current down to a reasonable level.