# Basic electronics

Discussion in 'Electronic Basics' started by Richard Harris, Jan 17, 2005.

1. ### Richard HarrisGuest

Hi,

Current is directly proportional to Voltage.
E=I

There for I=E, E=9V, I=9A ?

If this is so, how come you can get a 4.8 V battery in 720 mA and in
1200 mA ?

Would this 4.8 battery allow you to connect to a device that required a

Thanks.

2. ### Andrew HolmeGuest

Proportional does not mean equal. Resistance is the constant of
proportionality:

E = IR or I =E/R
Are you quoting maximum current (mA) or capacity in milliamp-hours (mAh)
there?
Possibly, yes. What sort of battery is it? Can you post a link to the
spec?

The capacity (= stored charge = current * time) determines how long it will
last.

3. ### Peter BennettGuest

in a resistive circuit.
No - E = I/R
No. The current depends on the resistance, as well as the voltage.
I suspect that your 4.8 V batteries have a _capacity_ of 720 mA-hours
or 1200 mA-hours. That is, they could theoretically deliver 720 mA
(or 1200 mA) for an hour before becoming fully discharged.
Yes - but it won't run it for long.

4. ### Bob MyersGuest

Ummmmm...Peter?.....

Bob M.

5. ### jim wGuest

Obviously, he meant conductance, not resistance, in that post. ;-)