Basic questions about polarity and resistances

[iwkse]

Hi, I'm studying electronics since little time, so excuse me if my questions are very basic but I guess you can help me to clarify dubts.

1. If I use a voltmeter and I measure a 4.5V battery, and I connect the COM cable to positive and Vohm cable to negative I get a negative number on the display. Is this normal? So it means there are n amount of electrons (negative sign) that still have to travel to the opposite side?

2. I was reading that resistance reduce the voltage..here I had a doubt because I though it reduces the current. Could you clarify?

Thanks!

 

[Audioguru]

1. If I use a voltmeter and I measure a 4.5V battery, and I connect the COM cable to positive and Vohm cable to negative I get a negative number on the display. Is this normal?

It is normal and is showing the polarity of the contacts on the battery. Do not think about what the electrons are doing.

2. I was reading that resistance reduce the voltage..here I had a doubt because I thought it reduces the current. Could you clarify?

A dead short circuit has no resistance or an extremely low resistance and causes as much current to flow as is possible. Obviously it causes the voltage to drop very low because the resistance of the power source is in series with the dead short and you are measuring the voltage across the short. A high resistance across a power source has little effect on the voltage because then the current is very low and the voltage dropped across the resistance of the power source is very low.

 

[barry]

To elaborate on Audioguru's answer, two words: Ohm's Law. This defines the relationship between voltage, current and resistance. It is the most fundamental concept in electricity/electronics. Learn it. Know it. Love it.

V=I/R

 

[iwkse]

Thanks to both of you, it helped to understand more.
The Ohm's law yeah..I could have guess that, when quantities are dependent!
I talked about electrons..just because I like to understand well, go into details and check if it's the right way to follow.
Regards

 

[darkgnat]

Electron flow is in the opposite direction of the "traditional" current flow which goes from positive to negative (the OPPPOSITE of the way electrons actually flow) . So keep that in mind as you review math/circuits, as they will almost all use flow from + to - (or ground).