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A sensor is exposed for time t to a lamp...

A sensor is exposed for time t to a lamp of power P placed at a distance l. The sensor has an opening that is 4d in diameter. Assuming all energy of the lamp is given off as light, the number of photons entering the sensor if the wavelength of light is `lambda` is:

A

`N = (Plambdad^(2)t)/(hcl^(2))`

B

`N = (4Plambdad^(2)t)/(hcl^(2))`

C

`N = (plambdad^(2)t)/(4hcl^(2))`

D

`N = (Plambdad^(2)t)/(16hcl^(2))`

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