A helium-neon laser has a power output of 1mW of light of wavelength 632.8 nm. Q. Calculate the energy of each photon in electron volt.

A helium-neon laser has a power output of 1mW of light of wavelength 6

1.	A helium-neon laser has a power output of 1mW of light of wavelength 632.8 nm. Q. Calculate the energy of each photon in electron volt.
Answer» Here, `lamda=632.8nm=632.8xx10^-9m`, Power, `P=9.42mW=9.42xx10^-3W` a. Now, energy of each photon in the light beam, `E=(hc)/(lamda)=(6.62xx10^-34xx3xx10^8)/(632.8xx10^-9)` `=3.14xx10^-19J=(3.14xx10^-19)/(1.6xx10^-9)=1.963eV` Also, momentum of each photon in the light beam, `p=(h)/(lamda)=(6.62xx10^-34)/(632.8xx10^-9)=1.046xx10^-27kgms^-1` b. The number of photons falling on the target per second, `N=(P)/(E)=(9.42xx10^-3)/(3.14xx10^-19)=3xx10^16s^-1` c. The required speed of the hydrogen atom, `V=(p)/(m_H)=(1.046xx10^-27)/(1.66xx10^-27)=0.63ms^-1`

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A helium-neon laser has a power output of 1mW of light of wavelength 632.8 nm. Q. Calculate the energy of each photon in electron volt.

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