Ohm's Law is the basic formula for electronics. With it, we may calculate Resistance (Ohms), Voltage (Volts) or Current (Amps) by knowing any two of the three values.
Instructions
Calculate Milliamps
1. A milliamp is one one-thousandth of an amp. By calculating the value in amps and dividing by one thousand, you will have a value of current in milliamps.
2. Ohm's Law is Voltage = Resistance X Current.
The derivations are:
Resistance = Voltage / Current
Current = Voltage / Resistance
3. Calculate Current using your known Voltage and Resistance as shown in Step 2.
Current (I) = Voltage (V) divided by Resistance (R)
I = V/R
Ex: if your voltage is 12V and resistance is 200 Ohms
I = V/R = 12 / 200 = 0.06 Amps
4. Knowing your Current in Amps, multiply by 1000 to see the value in milliamps
Ex: 0.06 Amps x 1000 = 60 milliamps
5. Given a known Voltage and Current, you may also derive Power (Watts).
Power = Voltage times Current ( P = V x I )
Ex: 12V x 0.06A = 0.72W or 720 milliwatts
Tags: Voltage Resistance, Calculate Milliamps, Current Amps, Current Voltage, known Voltage
