# how does electrical current flows through high resistance

#### Tor1990

Joined Jan 14, 2018
8
Regards. My question is the following how does electrical current flows through high resistance ?.For example we have a current of 1 A voltage of 10000 v resistance of 10 k .

So I understand that electrons are " raised to high potential "and therefore they have a lot of potential energy and they start to flow naw they have lot of kinetic energy and part of that energy is converted to heat energy bay "friction" (resistence)and other par allow them to keep moving through resistance .

I write exam so I need every help thanks

#### GopherT

Joined Nov 23, 2012
8,009
Regards. My question is the following how does electrical current flows through high resistance ?.For example we have a current of 1 A voltage of 10000 v resistance of 10 k .

So I understand that electrons are " raised to high potential "and therefore they have a lot of potential energy and they start to flow naw they have lot of kinetic energy and part of that energy is converted to heat energy bay "friction" (resistence)and other par allow them to keep moving through resistance .

I write exam so I need every help thanks
Think of the circuit as a bunch (leets say, 10000) 1V supplies going through 1 ohm.

The difference is, the 1V going through 1 ohm, is making 1 watt of heat on the resistor. In that example, the 10000 resistors will still generate 1W each and a total of 10000 watts but, think about this...

In your test question, you have 10000 volts and 1 amp = 10,000 watts. That's a lot of heat to get rid of (good if your resistor is a heater element and bad if it cannot withstand high temperatures - and catastrophic if the resistance of your resistor goes down with increasing temperature!)

• shortbus

#### nsaspook

Joined Aug 27, 2009
10,914
We should be careful about how the KE of electrons is generated and where the KE of electrons is utilized to understand how current flows through high resistance.
I'm not a big fan of the source potential electrons raised to high, fall down the hill analogy unless see the how, where and why.
The energy of this heat wasn't supplied by highly energized electrons as current in wires from your power supply to the resistor, they get highly energized inside the resistor. The 'current' just by itself supplies almost no energy to the hot resistors. ELECTRIC ENERGY IS NOT CARRIED BY INDIVIDUAL ELECTRONS (usually) in wires but that's a subject for a different day. In the circuit loop from power supply to resistors(s) the current is the same but the voltage drop across the connection wires from the power source to resistor is low so when we take the product of current and voltage the power/energy flowing into this wire is low. Across the resistor we have almost the entire power source voltage and the series current of the circuit when we take the product of current and voltage to calculate power/energy flowing into the resistor, it is high. This resistor voltage drop electrically accelerates free electrons in the resistor, these electron collide with the atoms in the resistor and release the transferred potential electrical energy as kinetic energy to the atoms (Joule heating).

"In terms of electrons" doesn't completely explain why the resistor gets hot in a circuit. The electrical energy normally travels in the space surrounding the wire/connections when circuit resistance is low and the electrons (that usually don't carry electrical energy in the circuit) form part of a waveguide for energy from source to load. When the electrical resistance increases at a spot in the circuit the electrical energy surrounding the conductors starts to move (converted to kinetic energy in the atoms) into the actual conductors (resistor) from the surrounding space into that spot causing heating as the electrical energy is transformed into thermal energy and is dissipated there instead of flowing in space. We normally design electrical circuits to reduce the amount of electrical energy carried by electrons to the lowest amount practical because space is a much better energy moving media for energy in fields than matter with free electrons.

slight edit of my original text

#### wayneh

Joined Sep 9, 2010
17,201
...how does electrical current flows through high resistance ?
I'm not sure what you are really asking. All electrical current flows for the same reason - it is responding to an electric field (voltage) which acts on the charge much like gravity acts on mass. A charge in a circuit, when it sees a field, will tend to fall downhill. Or perhaps it's more accurate to say that it moves randomly but once it has fallen downhill and released some energy, there is no way for it to fall back uphill.

#### ColinPatra

Joined Jan 27, 2018
28
I'm not happy with the idea of KE. The drift velocity of electrons at a current of 1A in Cu is around 10-5 m/s (Google 'drift velocity of electrons in copper)

#### MrChips

Joined Oct 2, 2009
28,137
I'm not happy with the idea of KE. The drift velocity of electrons at a current of 1A in Cu is around 10-5 m/s (Google 'drift velocity of electrons in copper)
The drift velocity is not the same as the velocity of the electron.

kinetic energy = ½ m v^2

#### nsaspook

Joined Aug 27, 2009
10,914
I'm not happy with the idea of KE. The drift velocity of electrons at a current of 1A in Cu is around 10-5 m/s (Google 'drift velocity of electrons in copper)
For good reason. The random motion of free electrons in copper is quite high (Fermi velocity, several ten or hundred thousands of meters per second for a metal) but it's totally random so the effective (mass) KE of that is zero. When you calculate the KE of the velocity (from the accelerating electric field E) of the free electron drift current it's a tiny fraction of the electrical field KE.