I'm looking at a circuit (part of a bigger circuit) that consist of a 10 ohm resistor and a red LED.
- It's running on 2.05V (checked with 2 different multimeters, ranging from from 2.047V to 2.05V).
- The voltage drop of the LED (again measured with 2 different multimeters on the live circuit) is 1.96V
- The resistor clocks in at 10.0 ohms exactly (again measured with 2 multimeters).
Now, according to Ohms law, the current flowing through the LED should be
I = V / R = (2.05V - 1.96V) / 10 = 9 mAmps
However, when hooking up my multimeters I get the following readings
- Multimeter A : 7.30mA
- Multimeter B : 6.10mA
It took them about 30 seconds to stabilize.
Why am I seeing that much difference ?
Multimeter A is about 4x more expensive than multimeter B, so I guess it will be more accurate, however, the difference between the measured 7.3mA and the calculated 9mA is too big to ignore no ? Or am I missing something ?