Suppose 10-17 J of light energy is needed by the interior of the human eye to see an object. How many photons of green light (λ=550 nm ) are needed to generate this minimum amount of energy?

Question

Suppose 10-17 J of light energy is needed by the interior of the human eye to see an object. How many photons of green light (λ=550 nm ) are needed to generate this minimum amount of energy? (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

The energy needed to see object =10-17 J Photon energy used to see object =( hc /λ) =(6.626 × 10-34 × 3.0 × 108/550 × 10-9) =3.61 × 10-19 J / photon ∴ Number of photons =(10-17/3.61 × 10-19)=27.7 ∴ Minimum number of photons required to see object =28.

Q. Suppose 10−17J of light energy is needed by the interior of the human eye to see an object. How many photons of green light (λ=550nm) are needed to generate this minimum amount of energy?

The energy needed to see object =10−17J Photon energy used to see object =λhc​ =550×10−96.626×10−34×3.0×108​ =3.61×10−19J/ photon ∴ Number of photons =3.61×10−1910−17​=27.7 ∴ Minimum number of photons required to see object =28.

Q. Suppose $1 0^{- 17} J$ of light energy is needed by the interior of the human eye to see an object. How many photons of green light $(λ = 550 nm)$ are needed to generate this minimum amount of energy?