In a p-n junction, a potential barrier of 250 MeV exists across the junction. A hole with a kinetic energy of 300 MeV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction from the p - side

Options

A. 100 meV
B. 50 meV
C. 150 meV
D. 200 meV

Answer

To solve the problem, we need to analyze the situation of a hole approaching a p-n junction with a potential barrier. Here is the step-by-step solution:

### Step 1: Understand the given values
- The potential barrier (V) across the junction is given as 250 MeV.
- The initial kinetic energy (KE_initial) of the hole approaching the junction is given as 300 MeV.

### Step 2: Determine the final kinetic energy after crossing the junction
When the hole approaches the junction from the p-side, it will lose some of its kinetic energy to overcome the potential barrier. The final kinetic energy (KE_final) of the hole after crossing the junction can be calculated using the formula:

\[ KE_{\text{final}} = KE_{\text{initial}} - V \]

### Step 3: Substitute the values into the formula
Now we can substitute the known values into the equation:

\[ KE_{\text{final}} = 300 \text{ MeV} - 250 \text{ MeV} \]

### Step 4: Calculate the final kinetic energy
Perform the subtraction:

\[ KE_{\text{final}} = 300 \text{ MeV} - 250 \text{ MeV} = 50 \text{ MeV} \]

### Conclusion
The kinetic energy of the hole when it crosses the junction is **50 MeV**.