The work function for caesium atom is `1.9 eV`. Calculate (a) the threshold wavelength and (b) the threshold frequency of the radiation. If the caesium element is irradiated with a wavelength `500 nm`, calculate the kinetic energy and the velocity of the ejected photoelectron.

Explanation

To solve the question step by step, we will break it down into parts (a) and (b) as requested.

### Given Data:
- Work function of caesium (W₀) = 1.9 eV
- Wavelength of incident radiation (λ) = 500 nm = 500 x 10⁻⁹ m
- Planck's constant (h) = 6.626 x 10⁻³⁴ J·s
- Speed of light (c) = 3.0 x 10⁸ m/s
- 1 eV = 1.602 x 10⁻¹⁹ J
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