2006-06-21 11:11:44 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
The formula for calculating current is known as Ohm's law. It is normally expressed as E=IR where E=voltage, I=current, and R=resistance. To calculate amperage(current) in a circuit, the formula would be as follows: I=E/R. For example, if the voltage measured across a resistor is 50V and its resistance is 25 ohms (ohms are the unit of measurement of resistance) the current would be 2 amps (50/25=2).
2006-06-21 11:36:43 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Ohms law as stated above.
If you want to test the current using a multimeter:
1. Make sure your multimeter can handle the current
2. Turn the circuit off before connecting mutimeter otherwise it could kill you
3. break the circuit (normally at the battery)
4. Connect the multimeter so it is part of the circuit. (For example, if you have a battery and an LED then: a wire goes from the + battery, through a wire connected to one lead of the LED, a wire from the other lead of the LED to - of the battery. To measure the current, disconnect the wire going to the - lead of the battery. Now connect the negative (black) of the mutimeter to the battery and the + (red) of the multimeter to the LED.)
5. turn the circuit on.
2006-06-21 11:33:11 · answer #2 · answered by oneidacarpetguy 2 · 0⤊ 0⤋
The equation normally used is Ohms's law, which says: Current is directly proportional to the voltage passing through a circuit and inversely proportional to the resistance.
Mathematically expressed;
i = V / r Where i = current
V = voltage and
r = resistance
2006-06-21 11:30:47 · answer #3 · answered by RealArsenalFan 4 · 0⤊ 0⤋
What other things do you already know about the circuit?
The most common formula is:
Current = Voltage / Resistance
2006-06-21 11:15:45 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Siyanda M says "proportional to the voltage passing through a circuit"
Voltage doesn't "pass through" a circuit.
Voltage is applied, or developed across a circuit or part of it.
Current flows through something.
And power is developed in something.
2006-06-21 15:02:15 · answer #5 · answered by dmb06851 7 · 0⤊ 0⤋
fast way is get on one of the wires going to or coming from the current load. then use a amp probe , a ac or dc depending on the type of current to be tested. other wise use any of the formula listed.
2006-06-21 11:56:41 · answer #6 · answered by Anonymous · 0⤊ 0⤋
You'd have to be more specific... Usually you don't need a formula to measure electrical parameters, just an instrument.
2006-06-21 11:14:50 · answer #7 · answered by Anonymous · 0⤊ 0⤋
it depends,,,, on what kind of circuit,,,
current ( amp ) = voltage (volts) / resistance (ohms)
2006-06-21 11:21:50 · answer #8 · answered by l_e_a_h_02 2 · 0⤊ 0⤋