Answer :
The energy of an electromagnetic wave that has a wavelength of 4.2nm is 4.731 × 10-¹⁷ J.
How to calculate energy of a wave?
The energy of a wave can be calculated using the following formula:
E = hf
Where;
- E = energy
- h = Planck's constant (6.626 × 10-³⁴J/s)
- f = frequency of the wave
However, the frequency must be calculated first as follows:
λ = v / f
Where;
- λ = wavelength
- v = speed of light (3 × 10⁸m/s)
4.2 × 10-⁹ = 3 × 10⁸/f
f = 7.14 × 10¹⁶Hz
Energy = 6.626 × 10-³⁴ × 7.14 × 10¹⁶
Energy of the wave = 4.731 × 10-¹⁷ J
Therefore, the energy of an electromagnetic wave that has a wavelength of 4.2nm is 4.731 × 10-¹⁷ J.
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