A Level Physics Practice Exam

An ion with a charge of +2e moving through a potential difference of 10V will have how much energy?

1. 5eV

2. 10eV

3. 20eV

4. 40eV

The correct answer is: 20eV

To determine the energy gained by an ion with a charge of +2e when moving through a potential difference of 10V, we can use the formula for electric potential energy: \[ \text{Energy (E)} = q \cdot V \] where \( q \) is the charge and \( V \) is the potential difference. In this case, the charge of the ion is +2e. The fundamental charge \( e \) is approximately \( 1.6 \times 10^{-19} \) coulombs. Therefore, the charge of the ion is: \[ q = 2e = 2 \times 1.6 \times 10^{-19} \text{ C} = 3.2 \times 10^{-19} \text{ C} \] When this ion moves through a potential difference of 10V, the energy gained by the ion can be calculated as follows: \[ E = (2e)(10V) \] To convert the charge into electronvolts (eV), we know that 1 eV is the energy gained by an electron moving through a potential difference of 1V, which is equivalent to \( e \) (1.