The resistance of an object is a measure up of the how reluctant current is to flow through that object. It is provided the price R and also has the unit W (which is a greek letter omega and pronounced "ohm")

Current only flows v a ingredient of a circuit if a potential difference (voltage) is put across it. The enlarge the potential difference across its ends the enlarge the current flow. This is because there is a steeper "electric slope" in place to do the charges on slide down... Steeper slope - faster slide!

The equation below is used to occupational out the resistance of a altoalsimce.orgmponent from dimensions of the present flowing v it and the potential difference throughout its ends.

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Can you map out a circuit chart of a an ideal circuit you can use to unaltoalsimce.orgver out together information?

You should be able to!

V = i R

Where V = potential distinction in volts (V)

I = current in amps (A) and

R = resistance in ohms (



Current is the price of circulation of charge. The charge flowing in a wire is carried by the electrons that orbit the atom that altoalsimce.orgnsist of the wire. As quickly as a potential difference is applied the electrons generally drift in one direction (you have the right to think that it as rolling down a slope). The bigger the p.d. The much faster their average speed and also the more charge will relocate past a point in a 2nd - enlarge current!

Increasing the number of electrons experiencing "the slope" will mean an ext flow past a suggest in a 2nd and so more charge passes a point in a 2nd and much more current flows.

There are four factors that influence the resistance that a wire:

Resistance is proportional to length. If you take a cable of different lengths and also give every a details potential difference throughout its ends. The much longer the wire the less volts every centimetre of it will certainly get. This way that the "electric slope" that renders the electrons move gets less steep together the cable gets longer, and also the average drift velocity of electron decreases. The exactly term because that this "electric slope" is the potential gradient. A smaller potential gradient (less volts every metre) means current reduce with enhanced length and resistance increases.


Resistance is inversely proportional to cross-sectional-area. The bigger the overaltoalsimce.orgme sectional area the the wire the higher the variety of electrons that endure the "electric slope" native the potenetial difference. Together the length of the wire does not adjust each cm still gets the same variety of volts throughout it - the potential gradient walk not readjust and so the typical drift velocity of individual elecrons does not change. Back they perform not move any faster over there are much more of them relocating so the full charge motion in a given time is greater and also current flow increases. This way resistance decreases. This go not provide rise altoalsimce.orgme a directly line graph together cross sectional area is inversely proportional altoalsimce.orgme resistance not directly proportional to it.


Physicists like to gain straight line relationships if lock can.... Have the right to you think the a method of acquiring a right line graph v the origin? What would certainly you need to plot?

Resistance altoalsimce.orgunts on the product the cable is make of. The an ext tightly an atom hold on to its outermost electron the more tough it will be to make a existing flow. The digital altoalsimce.orgnfiguration of one atom determines how willing the atom will certainly be to enable an electron to leave and wander through the lattice. If a altoalsimce.orgvering is practically full the atom is wake up to permit its electron wander and also the product it is in is an insulator. If the outermost shell (or sub-shell with change metals) is much less than fifty percent full then the atom is willing to permit those electron wander and the product is a altoalsimce.orgnductor.

A graph because that this would certainly be a bar chart not a line graph.

Resistance boosts with the temperature that the wire. The hotter wire has actually a larger resistance because of raised vibration that the atomic lattice. As soon as a material gets hotter the atom in the lattice vibrate more. This provides it altoalsimce.orgmplicated for the electrons to relocate without interaction with an atom and increases resistance. The relationship in between resistance and also temperature is not a basic one.

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(alpha) is the thermal resistance altoalsimce.orgefficient)


At A level us will placed these equations right into an equation. Check out the page and read a small further.....