An object is placed at a certain distance on the principal axis of a concave mirror. The image is formed at a distance of 30cm from the mirror. Find the object distance if radius of curvature R=15cm.​

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

360seconds i 1 hr

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m