Suppose you measure the terminal voltage of a 1.585-V...

Suppose you measure the terminal voltage of a 1.585-V alkaline cell having an internal resistance of $0.100 \Omega$ by placing a $1.00-\mathrm{k} \Omega$ voltmeter across its terminals (see below). (a) What current flows? (b) Find the terminal voltage. (c) To see how close the measured terminal voltage is to the emf, calculate their ratio.

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Key Concepts

Internal Resistance

Internal resistance is an inherent property of a real battery that causes a voltage drop when current flows. It results in the measured terminal voltage being lower than the battery’s electromotive force (emf) under load conditions.

Terminal Voltage

Terminal voltage is the voltage available at the battery’s external terminals when current is drawn from the cell. It is calculated by subtracting the voltage drop across the internal resistance from the emf, reflecting the effect of load conditions on the battery.

Ohm’s Law

Ohm’s Law is a fundamental principle stating that the current through a resistor is proportional to the voltage across it and inversely proportional to its resistance. This law is used to calculate current flow and voltage drops in circuits, including those involving internal resistances.

Loading Effect of Measurement Devices

The loading effect refers to the influence that a measuring instrument, such as a voltmeter with finite internal resistance, can have when connected to a circuit. This effect can alter the circuit conditions, resulting in a measured voltage that is slightly different from the true no-load emf.

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