Question

The energy of an electromagnetic radiation is 3x10-12ergs. What is its wavelength in nanometers?
(h = 6.62510-27erg.sec; c = 31010 cm.sec-1
) [ ]
1) 400 2) 228.3 3) 3000 4) 662.5

Answer 1

Given:

Energy of electromagnetic radiation = 3 × 10⁻¹² ergs

h = 6.625 × 10⁻²⁷ erg.sec

c = 3 × 10¹⁰ cmsec⁻¹

To find:

Wavelength of electromagnetic radiation

Solution:

Formula used for calculation Energy of an electromagnetic radiation will be,

In terms of frequency,

         E = hν

here E = energy of electromagnetic radiation

        h = plank's constant

        ν = frequency

we know that,

                       $\nu = \frac{c}{\lambda}$

here, ν = frequency

         c = speed of light

         λ = wavelength of electromagnetic radiation

so, putting frequency value in first equation, we get

In terms of wavelength,

           $E = \frac{hc}{\lambda}$

           $\lambda = \frac{hc}{E}$

substituting all the values in above equation, we get

          $\lambda = \frac{6.625 \times 10^-^2^7 \times 3 \times 10^1^0}{3 \times 10^-^1^2}$

          $\lambda = \frac{19.875 \times 10^{-17} }{3 \times 10^{-12}}$

         λ = 6.625 × 10 ⁻⁵ cm

Therefore, wavelength of electromagnetic radiation will be 6.625 × 10⁻⁵ cm.