E.m.f and Internal Resistance

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Batteries have resistance.

  • Resistance comes from electrons collliding with atoms and losing energy.
  • In a battery, chemical energy is used to make electrons move. When they move, they collide with atoms inside the battery.
  • This resistance is internal resistance!
  • Internal resistance is what makes cells warm up.
  • The amount of electrical energy the battery produces per unit charge is called the electromotive force (e.m.f)
  • The p.d. across the resistance of the components in the circuit is called the terminal p.d.
  • If there was no internal resistance, the terminal p.d. would be the same as the e.m.f. However, in real power supplies there is ALWAYS energy lost overcoming internal resistance.
  • Energy wasted overcoming internal resistance is called lost volts.

Many calculations about e.m.f and internal resistance.

One equation interpereted…


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