Question

What is the range of frequencies associated with
(a) Infrasound?
(b) Ultrasound?

Answer 1

Ultrasound $\Rightarrow$ can't be heard by humans

So start from $20,000Hz$ to $10$ mera $Hz$

Infraved waves - start from red edge

i.e., nearly from $700nm$ to $1mm$ in wavelength

$e-$frequency $430\times {10}^{12}Hz$ to $300\times {10}^{9}Hz$