1. Concept: The energy gained by a charge moving across a potential drop is equal to the product of charge and voltage, where fundamental unit 'e' must be expanded to its Coulomb value.
2. Formula: $$ Energy = q \Delta V $$
3. Solution: - Identify the charge: \( q = 5e \).
- Identify the voltage: \( V = 25 \text{ V} \).
- Energy in electron-Volts (eV): \( E = (5e) (25 \text{ V}) = 125\text{ eV} \).
- To convert eV to Joules, substitute \( e = 1.6 \times 10^{-19} \text{ C} \).
- Energy in Joules: \( E = 125 \times 1.6 \times 10^{-19} \text{ J} \).
4. Why other options are incorrect: Option A misses the 1.6 multiplier entirely. Option B is simply the charge of a single electron. Option D assumes macroscopic Coulombs rather than elementary charges.
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