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A radioactive source emits X–rays of very short wav...

A radioactive source emits X–rays of very short wavelength (10 -13m ). what is the frequency of these rays?

A.

2 × 1018HZ

B.

3 × 10 19HZ

C.

3 × 1021HZ

D.

3 × 10-19HZ

Correct answer is C

Wavelength(λ)=1013m

Speed of X-ray = speed of light C=3×108m/s

Frequently (f) = ?

Using V = f\lambda (or (– f π for electromagnetic wave)

f = \frac{c}{\lambda} = 3 \times 10^{8} ÷ 10^{-13} = 3 \times 10^{8} \times 10^{13}

= 3 \times 10^{8} \times 10^{13}

= 3 \times 10^{21}Hz