Simple Parallel Combination Question

[shaiqbashir]

Hi Guys!

well! today i have a very simple question to u. The circuit which i have drawn below is a simple parallel combination circuit. Can u Tell me the voltage across each resistor separately.i.e.

What is the voltage across 20ohm resistor?

What is the voltage across 100ohm resistor?

Im not joking here, i need an answer, thanks in advance

                            20ohm
                  ____/\/\/\/\/\____
                  |                          |
                  |                          |
                  ____/\/\/\/\/\/\___
                            100ohm
                  |                          |
                  |                          |
                  |              |          |
                  |______|  |_____|
                              |  |
                                  |
                             
                            9V

well! i know that its a terrible drawing, sorry but i couldnt attached my circuit here. Hope u can understand that.
 
 

[audioguru]

Hi Shaiq,
If your 9V power supply can supply 540mA (a little 9V battery probably can't, its voltage will drop with such a high current) then it is obvious that both resistors are connected directly to the 9V supply, therefore both have 9V across them. ;D

Did you measure any gain from your Mosfet amplifier?

[Mukhalled]

Hi

You have a parallel connection which means all the resisters will have the same voltage so it doesn't matter if you have 20ohm resister or 20kohm resister  ;)

good luck

[Guest SM2GXN]

Hi shaiqbashir!

I pass you a link to an online electronic course that cover resistors in parallel and series.
There is other good things to read about in this course.
Check it out and let me know what you think.

Bjorn

[shaiqbashir]

Well! My friends donot think that im joking here!!!!


I know all that which u told me. Well! i have seen that theoritically its working but practically not perhaps.

I made the same circuit which i have drawn in my 1st post above. When i checked it thru the Multimeter, the result was awful!!!

it was giving me very  less than 9V drop across both 20ohm resistor and 100ohm resistor. I have changed the multimeter, but the otherone was also giving me the same results, which i got from the 1st.

Tell me why im not getting 9V across each resistor heere. Is Parallel combination law is not violating here.

Secondly if i suppose that ok Parallell combination law is correct, tell me is this not violating the Law of Conservation of Energy. If i follow the parallel combination, then it would simply mean that i can connect the bulbs of whole town across one source( Lets say of 100V) and each bulb would be having 100 V  across it.

Isnt that terrible?

I dont think that this law is practically true, plz clearify this point.

Thanks

[audioguru]

Hi Shaiq,
I told you that your 9V supply must be able to provide 540mA to the resulting 16.67 ohms combination of the two resistors. ::)
I told you that a little 9V battery cannot supply such a high current, so its voltage would drop. ::)

To do this test properly you need a 9V regulated supply whose voltage doesn't drop when loaded with 16.67 ohms. The 9V supply must be able to supply at least 540mA.

Your little 9V battery has an internal resistance. Its resistance causes a voltage drop like any resistor with current in it. It is in series with your load, reducing the voltage to your load. Feel the temperature rise in your little 9V battery. Its temperature rises due to the power being dissipated by its internal resistance when it is loaded.

Instead of a little 9V battery maybe you used an AC/DC adapter. It also has an internal resistance. Measure its voltage without a load. If it is rated for 9VDC at full load then its voltage will be much higher than 9V without a load, because its designers selected a transformer with a higher output voltage and they allow its internal resistance to drop the output voltage down to its 9V rating at full load.

Your home's voltage source also has an internal resistance. If you connect all the bulbs of your town across your home's voltage source then a voltage drop will occur across the resistance, dropping the output voltage to the bulbs and causing a lot of heat in the resistance which will probably blow-up your home's voltage source.