Resistance of a wire
- As electrons pass through a wire, they collide with the metal ions in the wire
- These collisions transfer energy away from the kinetic store of the electrons, which causes them to slow down
- The energy from the electrons is transferred to the kinetic store of the vibrating metal ions
- This causes the vibration of the ions to increase (increased temperature)
- As the vibration of the ions increases, the more the electrons collide with them (increased resistance)
Electron collisions in a metal wire
Electrons collide with metal ions, which resist their flow
- If the wire is longer, each electron will collide with more ions, and so there will be more resistance:
- The longer a wire, the greater its resistance
- If the wire is thicker (greater diameter) there is more space for the electrons and so more electrons can flow:
- The thicker a wire, the smaller its resistance
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