An electron having a kinetic energy of 100eV circulates in a path of radius 10cm in a magnetic field. Find the magnetic field and the number of revolutons per second made by the electron.

Explanation

To solve the question, we need to find the magnetic field (B) and the number of revolutions per second (f) made by an electron with a given kinetic energy (KE) and radius of circular motion (r).

### Step 1: Convert Kinetic Energy to Joules
The kinetic energy (KE) of the electron is given as 100 eV. We need to convert this energy into joules. The conversion factor is:
1 eV = 1.6 × 10^-19 J.

So, the kinetic energy in joules is:
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