Is it true that if you double the current through a wire then you double the vol…

Is it true that if you double the current through a wire then you double the voltage loss and if you halve the current then you halve the voltage loss?

Yes. When you try to push current through a wire, the voltage drop across that wire (i.e. the energy lost by each charge passing through that wire) is proportional to the number of charges flowing through that wire each second (i.e. the current through the wire). If you double the number of charges flowing through the wire each second, then each charge will lose twice as much energy (the voltage drop across the wire will double). If you halve the number of charges flowing through the wire each second, then each charge will lose half as much energy (the voltage drop across the wire will halve).

When going from 12 volts to 240 volts, is the point that with higher voltage the…

When going from 12 volts to 240 volts, is the point that with higher voltage the power transfer proceeds with fewer particles?

Yes. If you use higher voltages, you can transfer the same amount of power with a small current of charged particles. The energy lost in the transmission through wires increases as the square of the amount of current through those wires so reducing that current is very important.

What are the relationships between Joules, Coulombs, Amperes, Volts, and Watts?

What are the relationships between Joules, Coulombs, Amperes, Volts, and Watts?

A Joule is a unit of energy; the capacity to do work. A Coulomb is a quantity of electric charge; equal to about 6,250,000,000,000,000,000 elementary charges. An Ampere is a measure of current; equal to the passage of 1 Coulomb of charge each second. A Volt is a measure of the energy carried by each charge; equal to 1 Joule of energy per Coulomb of charge. A Watt is a measure of power; equal to 1 Joule per second. A current of 1 Ampere at a voltage of 1 Volt carries a power of 1 Watt. That is because each Coulomb of charge carries 1 Joule of energy (1 Volt) and there is 1 Coulomb of charge moving by each second (1 Ampere). That makes for 1 Joule of energy flowing each second (1 Watt).