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In astronomical observations, signals ob...

In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of `3.15xx10^(-18)J` from the radiations of 600 nm, calculate the number of photons received by the detector.

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Wavelength, `lamda=600nm=600xx10^(-9)m`
Energy of photon`=(hc)/(lamda)=((6.626xx10^(-34))xx(3xx10^(8)))/(600xx10^(-9))`
`=3.133xx10^(-19)J`
Number of photons detected by the detector
`=("total energy received by the detector")/("energy of each photon")`
`=(3.15xx10^(-18)J)/(3.313xx10^(-19)J)=9.15~~10`photons.
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