A battery pack is constructed using six 1.5\text{ V} cells connected in series. If five of… — Armed Services Vocational Aptitude Battery (ASVAB)

A battery pack is constructed using six $1.5\text{ V}$ cells connected in series. If five of the cells are connected in series-aiding polarity and one cell is accidentally connected in reverse (series-opposing polarity), what is the total electromotive force (EMF) across the output terminals in volts?

Answer: 6 V

Answer

The net electromotive force across the terminals is

6.0\text{ V}

Electromotive force (EMF) values in a series circuit combine algebraically according to polarity. The five aiding cells provide

+7.5\text{ V}

(

5 \times 1.5\text{ V}

), while the single reversed cell opposes the chain with

-1.5\text{ V}

. The resulting net output voltage is

7.5\text{ V} - 1.5\text{ V} = 6.0\text{ V}

Step-by-Step Solution

Calculate the combined electromotive force of the cells connected in series-aiding polarity.

5 \times 1.5\text{ V} = 7.5\text{ V}

Cells oriented in the same aiding polarity add their potential differences directly.

Subtract the potential difference of the reversed (series-opposing) cell from the aiding sum.

7.5\text{ V} - 1.5\text{ V} = 6.0\text{ V}

A reversed cell creates an electromotive force in the opposite direction, opposing the aiding cells and subtracting from the net terminal voltage.

Key Concept

Series cell electromotive force addition and opposing polarity subtraction

Estimated Time:1m 0s

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