Super Easy Noob Questions about Circuit (see pics inside) [Updated]

Using Arduino General Electronics
4

  1. Red = power, black = ground?
    Probably. If not, switch them around. Got a 5V source? Connect a 270 to 1K resistor to +5, to red wire, then black wre to Gnd.

  2. Why does something need to be grounded?
    Electricity needs to make a loop from positive to negative - otherwise there is no current flow.

  3. Is there anyway to tell, just from the picture the LED voltage and current requirements?
    No. But you can figure about 40mA max should be allowed to flow, and there will be ~2.5 to 3.5V across the LEDs.
    Call it 3V. Then (5V - 3V)/.04A = 50 ohm resistor as the lowest value. With 270 to 1K you can measure the Vf of the LEDs and adjust your resistor from there for max brightness if needed.

  4. Why does the wiring that is closer to the LED look fatter?
    Thicker insulation? More durable wire? Really, 30 AWG wirewrap wire is all that is needed for 40mA, but it's not very durable in a vibration environment.

  5. What determines how wide/thick the wiring and the board is? (I assume it is an IV requirement but how would I go about calculating this?
    Wire thickness determined by current and voltage drop needs.
    Board thickness determined by engineering/manufacturing. 1.6mm thick is common.

  6. How do I model this circuit on paper?
    Draw two LEDs in parallel.

  7. Since the power goes to both LEDs, are these in series or parallel and why does it matter?
    Two in parallel will share same source voltage, if their Vf is different enough then 1 may not turn on. Current needed is double.
    Two in series need a higher source voltage to turn both on, but will share the same current.
    If both have a Vf of 3V and the source is only 5V, then there is no chance of both turning on.