A monochromatic light of wavelength ` lambda` is incident on an isolated metallic sphere of radius a. The threshold wavelength is ` lambda_0` which is larger than ` lambda`. Find the number of photoelectrons emitted before the emission of photoelectrons will stop.

Explanation

To solve the problem of finding the number of photoelectrons emitted from an isolated metallic sphere when monochromatic light of wavelength \( \lambda \) is incident on it, we can follow these steps:

### Step 1: Understand the Conditions
We are given:
- A metallic sphere of radius \( a \).
- Monochromatic light of wavelength \( \lambda \) is incident on the sphere.
- The threshold wavelength \( \lambda_0 \) is greater than \( \lambda \).

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