Question

What is the energy of an electromagnetic wave that has a wavelength of

7.0 x 10-12 m? Use the equation E= hc where hc = 1.99 × 10-25 J-m.
OA. 2.8 × 10-14 J
OB. 1.4 x 10-36 J
OC. 9.0 x 10-37 J
OD. 7.2 x 1035 J
SUBMIT

Answer 1

`{\qquad\qquad\huge\underline{{\sf Answer}}}`

Here we go ~

`\qquad \sf  \dashrightarrow \:E = (hc)/(\lambda)`

here,

• 
  `\sf{hc = 1.99 × {10}^(-25) J - m}`

• 
  `\sf{\lambda = 7.0 × {10}^(-12)}`

____________________________________

`\qquad \sf  \dashrightarrow \: E = \cfrac{1.99 * 10 {}^( - 25) }{7 * 10 {}^( - 12) }`

`\qquad \sf  \dashrightarrow \: E= \cfrac{1.99}{7} * 10 {}^( (- 25 + 12)) { }`

`\qquad \sf  \dashrightarrow \:E= 0.284 * 10 { }^( - 13)`

`\qquad \sf  \dashrightarrow \: E= 2.84 * 10 { }^( - 14\:\; ) J\: \:`

so, correct choice is A