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NEETPhysicsDual Nature of Matter

A continuous wave laser pointer emits 5 10¹⁵ photons per second, delivering a total optical power of 3.3 10⁻³ W . The wavelength of the emitted monochromatic light is: (h = 6.6 10⁻³⁴ J s , c = 3 10^8 m/s )

Options

  1. A3000 nm
  2. B300 nm
  3. C3 10⁻⁷ nm
  4. D600 nm

Correct answer

B. 300 nm

Step-by-step solution

The power P of the laser is related to the number of photons emitted per second n and the energy of a single photon E by the equation: P = nE = n ( hc ) Rearranging the formula to solve for wavelength : = nhc P Substitute the given values: = 5 10¹⁵ 6.6 10⁻³⁴ 3 10^8 3.3 10⁻³ = 99 10⁻¹¹ 3.3 10⁻³ = 30 10⁻⁸ m To convert to nanometers, multiply by 10^9 : = 30 10⁻⁸ 10^9 nm = 300 nm Answer: 300 nm

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