2006-09-07 22:01:22 · 7 answers · asked by fishfinger 4 in Science & Mathematics ➔ Physics
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2006-09-07 22:04:54 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Good question. Imagine electricity to be like water - and the amount of water flowing is the current, measured in amperes or amps in electricity. The voltage is like water pressure,More pressure. More flow. But some thing resist the flow. Passing electricity through a lighbulb resists the flow. Now we take a car battery and connect it to a light bulb at 12 volts the electricty flows from the battery through the bulb and back to the battery. In the early days it was though it flowed from positive to negative. But the electrons actually went the other way! Too late we not altering all the books now and what does it matter anyway? Now we come to alternators where the electricity flows from postive to negative for a fraction of a second reverses and flows the other way and continues to do this. If you have an AC (alternating current) appliance in your home, read the label. It probably says 50Hz. That means it goes one way for 1/100 of a second and the other way for 1/100 of a second - so there are 50 cycles per second - hence 50 Hz. So it's just the pressure going the other way. Like taking the hose of one tap and attaching the other end to a tap instead. But 100 times every second! You can also connect a volt meter on a car battery to positive and then to the earth of the car and it will read -12V or there abouts. It is -12 relative to the positive side. But swop he leads around and you get +12V the terminal is +12V relative to the grounded side. Everything is relative. A train going 80 miles an hour is only 10 miles an hour faster than the car at 70 miles per hour!
2006-09-08 04:10:11 · answer #2 · answered by Mike10613 6 · 0⤊ 0⤋
Voltage is actually the difference between two zones of electrical potential energy. For example across the ends of a battery you have 9 V, because one side has 9 V higher electrical potential energy than the other. You extract this energy and use it, by letting it flow from the high side (+) to the lower side (-) in a controlled way, like through your walkman.
We sometimes say that the + side is the positive voltage terminal and the - side is the negative voltage terminal. Because voltage is a difference and is not absolute it is equally correct to say that the difference between the - and the + is -9 V. It just depends on which side you use as a reference.
9 - 0 or 0 - 9
Zero being the reference.
I work with some equipment that requires both +15V and -15V both referenced to a common 0V.
2006-09-07 23:31:14 · answer #3 · answered by SmartBlonde 3 · 0⤊ 0⤋
You may be aware that the volt is the unit for potential difference and potential is the work done per unit charge to bring it from one point to other. If we are doing work to bring that charge to a location then it is increasing its pontential state. If the charge moves by it self then it is decreasing its potential.
The positive and negative concepts are taken about a mean position only. The negative means that potential is less than the 'zero' potential of interest. If we place an electron in the 'zero' potential it move away from the negative potential.
2006-09-07 22:30:46 · answer #4 · answered by libranjiss 1 · 1⤊ 0⤋
A negative voltage is where the "positive" supply is lower than the ground rail.... Ie that current flows from the 0V to the negative supply.
2006-09-07 22:08:37 · answer #5 · answered by break 5 · 0⤊ 0⤋
It depends on zero reference which you assigned .If you have two 1.5V batteries connected in series and you assign the center point to be zero volt.Then positive of the top battery is +1.5 V with reference to the center and negative end of the lower battery will be -1.5Volts with reference to center.
But if you assigned the negative end to be zero volt then center point is +1.5 V and positive of the top battery will be +3.0 V with reference to negative end.
If positive of the top battery was assigned to be zero then
the center point and negative end will be -1.5 V and -3.0 V respectively.
Hope this will help!
2006-09-08 00:15:26 · answer #6 · answered by dwarf 3 · 0⤊ 0⤋
negative voltage only apples to D.C currents all it really means is the mesring device is plugged in the wrong way. most D.C circuits have diode in them to prevent components from getting damaged by crrent going in the wrong direction anyway
2006-09-07 22:08:42 · answer #7 · answered by Anonymous · 0⤊ 0⤋