A Perfectly Black Sphere 18

Short Answer

A perfectly black sphere 18.0 cm in diameter is held at a temperature of 215°C.
(σ = 5.670 × 10^-8 W/m² • K⁴,Wien displacement law constant is 2.90 × 10^-3 m • K, ,c = 3.00 × 10⁸ m/s)
(a)Near what wavelength does this sphere radiate most strongly?
(b)If all the radiated energy were at the wavelength found in part (a),how many photons would the sphere emit each second?