The potential energy of the electron in the first Bohr orbit in the hydrogen atom is `-27.2` eV. What is its kinetic energy in the same orbit?

Explanation

To find the kinetic energy of the electron in the first Bohr orbit of a hydrogen atom, we can use the relationship between potential energy (PE) and kinetic energy (KE) in this context.

### Step 1: Understand the relationship between potential energy and kinetic energy
In a hydrogen atom, the kinetic energy (KE) of the electron is related to its potential energy (PE) by the formula:
\[ KE = -\frac{PE}{2} \]
This relationship arises from the balance of forces acting on the electron in its orbit.
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