PHYS 102 Chapter Notes - Chapter 19: Internal Resistance, Resistor, Electric Potential

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17 Aug 2017

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A device that transforms another type of energy into electrical energy is called a source of emf. A battery behaves like a source of emf in series with an internal resistance. The emf is the potential difference determined by the chemical reactions in the battery and equals the terminal voltage when no current is drawn. When a current is drawn, the voltage at the battery"s terminals is less than its emf by an amount equal to the potential decrease across the internal resistance. When resistances are connected in series (end to end in a single linear path), the equivalent resistance is the sum of the individual resistances: In a series combination, is greater than any component resistance. When resistors are connected in parallel, the reciprocal of the equivalent resistance equals the sum of the reciprocals of the individual resistances: In a parallel connection, the net resistance is less than any of the individual resistances.

Related Questions

A real battery is not just an emf, we can model a real 1.5V battery as a 1.5 V emf in series with a resistor known as the internal resistance. A typical battery has 1.0 Ω internal resistance due to imperfections that limit the current through the battery. When there's no current through the battery, and thus no voltage drop across the internal resistance, the potential difference between its terminals is 1.5 V, the value of the emf. Suppose the terminals of this battery are connected to a 3 Ω resistor.

what fraction of the battery's power is dissipated by the internal resistance?

violeteel500

1. The emf and the internal resistance of a battery are shown in the figure. If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery. What is the power dissipated by the resistor R?

2. The emf and the internal resistance of a battery are shown in the figure. When the terminal voltage V_ ab is equal to 17.4V, what is the current through the battery, including its direction?