Total voltage drop in series circuit

[bitem2k]

Im currently reading a book on electronics, that says that the sum of the Voltage drops across all components tied in series should equal the voltage of the battery.

However i tested cicuit on a breadboard with a led and a resistor, and measured the drops accross each and added them together. They did not add up to the supply voltage.

Anyone have any ideas?

Thanks very much.

 

[audioguru2]

Please tell us what are your voltage measurements.
Measure the battery voltage with it powering the LED when its voltage is reduced by the current.

 

[bitem2k]

Thanks for the reply.

worked out what the problem was.

This is very strange, but i was using a Nokia Charger which provides 8.78V with nothing connected., but for some reason when you measure the drops across everything connected (resistors) in series, it looses a volt or two!

Any idea why?

thanks

 

[audioguru2]

The voltage dropped on the Nokia charger because it is a constant current source or because it was overloaded or because it has lousy voltage regulation.

 

[bitem2k]

Righto.
Thanks