A radioactive source emits X–rays of very short wavelength (10\(^{-13}\)m ). What is the frequency of these rays?
A
2 × 1018HZ
B
3 × 10 19HZ
C
3 × 1021HZ
D
3 × 10-19HZ
Verified Correct Answer: C.
Physical Principles & Numerical Solution
\(Wavelength (\lambda) = 10^{-13}m\)
Speed of X-ray = speed of light \(C = 3\times10^{8}m/s\)
Frequently (f) = ?
\(Using V = f\lambda (or (– f \pi for electromagnetic wave)\)
\(f = \frac{c}{\lambda} = 3 \times 10^{8} \div 10^{-13} = 3 \times 10^{8} \times 10^{13}\)
= \(3 \times 10^{8} \times 10^{13}\)
= \(3 \times 10^{21}Hz\)
Source: Myschool Past Questions Archive (Record #40873)