An atom in its ground state absorbs a single photon of light and then relaxes back to the ground state by emitting an infrared photon (1,200 nm) followed by an orange photon (600 nm). Calculate the energy and frequency of the photon that was absorbed initially.

Frequency  OF absorbed photon =7.497 x 10^14 s^-1 ,Energy OF absorbed photon =4.97 X 10 ^-19J

Explanation:

The formula for ansorbd wavelength is given as

1/λabs = 1/λ1 + 1/λ2

1/λabs = 1/1200nm + 1/600nm

1/λabs = 0.0008333 +0.0016666

1/λabs =0.002499

λabs= 1/002499

λabs= 400.16nm

a

But Frequency =f = c / λ

Where

speed c =  3.0 x 10^8 m/s

wavelength λ (m) = 4.0016 x 10^-7m

Frequency = 3.0 x 10^8 m/s/ 4.0016 x 10^-7m = 7.497 x 10^14 s^-1

And energy = hc/ λ

h= Plank constant

c= speed of light

λ= Wavelength=4.0016 x 10^-7m

E= 6.626 X 10-34Js X  3.0 x 10^8 m/s/ 4.0016 x 10^-7m

Energy = 4.9675 x 10 ^-19J = 4.97 X 10 ^-19J

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied