Question

The frequency of ultraviolet rays is

• A. ${10}^{14}Hz$
• B. ${10}^{4}Hz$
• C. ${10}^{8}Hz$
• D. ${10}^{10}Hz$

Answer 1

The correct option is A ${10}^{14}Hz$

Orders of magnitude are written in powers of $10$ when the premultiplication factor is expressed between $1-10$. For example, the order of magnitude of $7500$ is $4$ since 75000 may be written as $7.5\times {10}^4$.
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light(violet) but longer than X-rays, that is, in the range 10 nm to $400nm.$
$c=\nu \times \lambda$
frequency range of UV, $\nu =\frac{c}{\lambda }$
$=\frac{3\times {10}^8}{400\times {10}^{-9}}$ - $\frac{3\times {10}^8}{10\times {10}^{-9}}$

$=7.5\times {10}^{14}-3\times {10}^{16}Hz$

Hence, order of frequency of UV rays is $14-16$.