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Ch 25: Current, Resistance, and EMF
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 25, Problem 28c

An idealized ammeter is connected to a battery as shown in Fig. E25.2825.28. Find the terminal voltage of the battery.
Circuit with ammeter, 10V battery, 2Ω and 4Ω resistors in series.

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1
Identify the components in the circuit: a battery with an emf of 12.0 V, a resistor of 8.0 Ω, and another resistor of 6.0 Ω.
Understand that the terminal voltage of the battery is the voltage across the battery when the circuit is closed, which is the emf minus the voltage drop due to the internal resistance.
Calculate the total resistance in the circuit. Since the resistors are in series, the total resistance R_total is the sum of the resistances: R_total = 8.0 Ω + 6.0 Ω.
Use Ohm's Law to find the current I in the circuit. Ohm's Law states that I = V / R, where V is the emf of the battery and R is the total resistance.
Calculate the terminal voltage V_terminal using the formula V_terminal = emf - I * r, where r is the internal resistance of the battery. If the internal resistance is not given, assume it is negligible for an ideal battery.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ohm's Law

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance. It is expressed as V = IR, where V is voltage, I is current, and R is resistance. This law is fundamental for analyzing electrical circuits and calculating the current flowing through components.
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Series Circuit

In a series circuit, components are connected end-to-end, forming a single path for current flow. The total resistance in a series circuit is the sum of individual resistances, and the same current flows through each component. Understanding series circuits is crucial for calculating the total resistance and voltage drops across each component, which affects the terminal voltage of the battery.
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Terminal Voltage

Terminal voltage is the voltage output of a battery when it is connected in a circuit, accounting for any internal resistance. It is calculated by subtracting the voltage drop across the internal resistance from the electromotive force (EMF) of the battery. In practical terms, terminal voltage is the actual voltage available to the external circuit, which can be less than the battery's EMF due to internal resistance.
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