Find the energy of a photon of light if the wavelength of the light wave is 6.88 x 10^–7 m.
A. 2.89 x 10^–19 J
B. 4.56 x 10^–40 J
C. 3.46 x 10^18 J
D. 7.56 x 10^–20 J

Question

Find the energy of a photon of light if the wavelength of the light wave is 6.88 x 10^–7 m.
A.	 2.89 x 10^–19  J
B.	 4.56 x 10^–40  J
C.	 3.46 x 10^18  J
D.	 7.56 x 10^–20  J

chmvijay · Answer

use E= hv
         =hc/lambda
lambda is wavelength
h- planks constant
c velocity of light in vacuum

anonymous · Answer

Here Lambda λ= 6.88*10^-7 m
E=hv or
E=hc/ λ
E=(6.63*10^-34)(3*10^8)/6.88*10^-7)
E=2.89*10^-19 J ( Option A)

What if I tell you a trick to solve it Fast just Solve the Exponents(Powers):
E= 10^-34 * 10^8 /10^-7
or E= 10^-34+8+7
E=10^-19 and Multiply the Coefficients 6.63*3/6.88 = 2.89