The total energy of an electron is 3.555 MeV, then its Kinetic energy is

Options

A. 3.545 MeV
B. 3.045 MeV
C. 3.5 MeV
D. None

Explanation

To find the kinetic energy of the electron given its total energy, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Information:**
- Total Energy (E_total) = 3.555 MeV
- Rest Mass Energy (E_rest) of an electron = 0.51 MeV (this is a known value)

2. **Use the Formula for Total Energy:**
The total energy of a particle is given by the equation:
\[ E_{\text{total}} = K.E + E_{\text{rest}} \]
where \( K.E \) is the kinetic energy and \( E_{\text{rest}} \) is the rest mass energy.

3. **Rearrange the Formula to Solve for Kinetic Energy:**
To find the kinetic energy, rearrange the equation:
\[ K.E = E_{\text{total}} - E_{\text{rest}} \]

4. **Substitute the Known Values:**
Substitute the values we have into the equation:
\[ K.E = 3.555 \text{ MeV} - 0.51 \text{ MeV} \]

5. **Calculate the Kinetic Energy:**
Perform the subtraction:
\[ K.E = 3.555 \text{ MeV} - 0.51 \text{ MeV} = 3.045 \text{ MeV} \]

6. **Conclusion:**
The kinetic energy of the electron is:
\[ K.E = 3.045 \text{ MeV} \]

### Final Answer:
The kinetic energy of the electron is **3.045 MeV**.

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