Eye detects the green light `(lamda=5000Å),5xx10^(4)` photons per square metre per second and the ear can detect `10^(-13)` watt per square metre. In form of power `10^(-13)` watt per square metre. In form of power detector, the eye is sensitive in comparison to the ear by

Options

A. 2 times
B. 3 times
C. 4 times
D. 5 times

Answer

D

Explanation

Energy of green photon, `E=(hc)/(lambda)`
`=((6.6xx10^(-34))(3xx10^(8)))/((5000xx10^(-10)))=(3.96xx10^(-19))J`
Energy received per second `=(3.96xx10^(-19))(5xx10^(4))`
`=1.98xx10^(-14)W//m^(2)`
Sensitivity of eye in comparison to ear=
`=("Power per square metre detected by ear")/("Energy received per second")`
`=(10^(-13))/((1.98xx10^(-14)))=5`