The kinetic energy of an electron accelerated from rest through a potential difference of 4V will be:

Options

A. 5V
B. 16V
C. 4eV
D. 16erg

Explanation

To find the kinetic energy of an electron accelerated from rest through a potential difference of 4V, we can use the relationship between electric potential energy and kinetic energy.

### Step-by-Step Solution:

1. **Understand the relationship between potential difference and kinetic energy**:
When an electron is accelerated through a potential difference (V), the work done on the electron by the electric field is converted into kinetic energy (KE). The formula relating potential difference and kinetic energy is:
\[ KE = eV \]
where \( e \) is the charge of the electron (approximately \( 1.6 \times 10^{-19} \) coulombs) and \( V \) is the potential difference in volts.

2. **Substitute the given values**:
In this case, the potential difference \( V \) is given as 4 volts. Therefore, we can substitute this value into the equation:
\[ KE = e \times 4 \]

3. **Calculate the kinetic energy**:
Now, substituting the value of \( e \):
\[ KE = (1.6 \times 10^{-19} \, \text{C}) \times (4 \, \text{V}) = 6.4 \times 10^{-19} \, \text{J} \]

4. **Convert the kinetic energy into electron volts (if necessary)**:
Since the kinetic energy is already expressed in terms of electron volts (1 eV = \( 1.6 \times 10^{-19} \, \text{J} \)), we can express the kinetic energy in eV:
\[ KE = 4 \, \text{eV} \]

5. **Final answer**:
Thus, the kinetic energy of the electron after being accelerated through a potential difference of 4V is:
\[ KE = 4 \, \text{eV} \]