Explain how Einstein's photoelectric equation enables us to understand the (i) linear dependence, of the maximum K.E. of the emitted electrons, on the frequency of the incident radiations (ii) existance of a threshold frequency for a given photoemitter.

Explanation

To understand how Einstein's photoelectric equation provides insights into the linear dependence of the maximum kinetic energy of emitted electrons on the frequency of incident radiation and the existence of a threshold frequency, we can break down the explanation into two parts.

### Step-by-Step Solution:

1. **Einstein's Photoelectric Equation**:
The photoelectric equation is given by:
\[
KE_{\text{max}} = h\nu - \nu_0
...