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Calculate how many electronvolts are in a kilowatt-hour. - Leaving Cert Physics - Question (b) - 2022

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Calculate how many electronvolts are in a kilowatt-hour.

Worked Solution & Example Answer:Calculate how many electronvolts are in a kilowatt-hour. - Leaving Cert Physics - Question (b) - 2022

Step 1

Step 1: Understand the conversion factors

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Answer

We know that:

1 eV (electronvolt) = 1.6×10−191.6 \times 10^{-19} joules.

Also, 1 kilowatt-hour (kWh) can be converted to joules using:

1 kWh = 1000 W × 3600 s = 3.6×1063.6 \times 10^{6} joules.

Step 2

Step 2: Calculate the number of electronvolts in a kilowatt-hour

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Answer

To find the number of electronvolts in a kilowatt-hour, we use the relation:

Number of eV=3.6×106 J1.6×10−19 J/eV\text{Number of eV} = \frac{3.6 \times 10^6 \text{ J}}{1.6 \times 10^{-19} \text{ J/eV}}

Performing the calculation gives:

Number of eV=3.6×1061.6×10−19=2.25×1025 eV\text{Number of eV} = \frac{3.6 \times 10^6}{1.6 \times 10^{-19}} = 2.25 \times 10^{25} \text{ eV}.

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