Electricity

Electricity is all around us from the small amounts of a spark between your finger and the car, to your phone and tv, to the huge amounts in lightning.

A fun way to see the effects of electricity (since you can't -see- electricity, just its effects) is to generate a static spark. In the dark (or low light to be safe) and with hard soled shoes, shuffle accross the carpet. After doing this for a few minutes move your finger close to a metal object like a door handle and watch the spark jump accross. For a more dramatic flash try doing it witha neon lamp for a big flash of light as the electricity is used to generate light.

Electricity

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Anonymous
172

resistors reduce the current

Anonymous
172

resistors reduce the current

Anonymous
172

resistors reduce the current

Anonymous
172

resistors reduce the current

Anonymous
172

Resistors oppose/limit Voltage and Current so yes it does reduce current and "takes" part of the voltage onto itself, which is nice if you want to use the voltage drop across the resistor

emfb
1

resistors provide resistance to the flow of current.

In the example of a led & resistor circuit the led will drop 1.4v leaving 3.6 volts across the resistor. Current is calculated by I = 3.6v/R. So for a 1K ohm resistor the series current in the circuit would be 3.6ma

If you were to substitute a variable resistor in the circuit, the voltage drop across the var resistor as the resistance is changed would for the most part remain constant (first approx.) but current would vary. This is useful to allow the brightness of the led to be changed by varying the series current.

Remember though too much current will burn out your led. Which is ultamatly why a resistor is needed in the first place... to limit current.

Anonymous
172

Then why does a led that needs say 1.4 volts work when you use a 5 volt source and a resister. If the resister doesn't drop the voltage surely 5 volts is reaching the resistor.

Anonymous
172

Ohm's law = E
---
I * R

E = Volts
I = Ampere
R = Resistance

As you increase resistance, your amperage drops. Voltage stays the same.

Anonymous
172

I have always been confused byt this, do resisters decrease the voltage or the current or both or what?

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