Your multimeter may not be accurate when measuring milliamps on a 10A scale.
1k resistor exact ohms = 950 (As per multimeter)
The resistance reading may not be “exact” either. No measurement is exact/perfect. Better meters are more accurate, and for example the meter I use at work gets calibrated once a year to keep it within spec. (At some point, if you can get your hands on a 1K/1% resistor you can check compare your meter’s reading to the known resistor value.)
If current flowing in the circuit (minus) LED current = Current wastage?
i.e 50mA - 8mA = 42mA wastage?
The current is a series circuit is the same through all series components the battery, the resistor, and the LED). This is one of [u]Kirchhoff’s Laws[/u].
Think of water flow through closed-pipes… The water-current flow has to be the same through all series pipes. That’s true even if there is a restriction (resistance) in one of the pipes. However, the pressure can be different on each side of the restriction. In the water analogy*, water pressure is voltage and water-flow is electrical current flow.
Another of Kirchhoff’s Laws describes how voltage is divided among series components.
Power (energy) is lost/wasted in the resistor. That power is converted to heat. Power is calculated as Voltage x Current.** So, with 8mA and 8.14V across the resistor, that’s about 64mW.
You have the same current through the wires, but since the resistance of the wires is (essentially) zero, you have (essentially) zero voltage across the wires, and (essentially) zero power is lost in the wires.
There is also some power wasted/lost in the LED, but that can’t be easily calculated. If the LED were 100% efficient all of the LED energy would be converted to light, but in reality it’s not 100% efficient and some energy is lost as heat.
- Don’t take the water analogy too far… If you cut a pipe you get zero resistance and water spills-out all over the place. If you cut a wire you get infinite resistance and no current flows.
Also, zero resistance in water pipes doesn’t cause any problems. With zero resistance in an electrical circuit too much current can flow and things can burn-up.
** Power can also be calculated as P = I2 x R or P = V2/R.