Question

please answer the 11th question

Answer 1

We know that Energy of a Photon is given by : E = hc/λ

Where h is the Planck's Constant = 6.625 × 10⁻³⁴ Joule - sec

c is the Speed of Light in Vaccum = 3 × 10⁸ meter per sec

λ is the Wavelength of the Photon

Let us Find the Energy of Violet light Photon :

Given λ = 4000A° = 4000 × 10⁻¹⁰ meter = 4 × 10⁻⁷ meter

Substituting all the values we get :

E = (6.625 × 10⁻³⁴ × 3  × 10⁸)/(4 × 10⁻⁷)

E = 4.96 × 10⁻¹⁹ Joules

Energy of a Photon of Violet Light = 4.96 × 10⁻¹⁹ Joules

Let us Find the Energy of Red light Photon :

Given λ = 7000A° = 7000 × 10⁻¹⁰ meter = 7 × 10⁻⁷ meter

Substituting all the values we get :

E = (6.625 × 10⁻³⁴ × 3  × 10⁸)/(7 × 10⁻⁷)

E = 2.83 × 10⁻¹⁹ Joules

Energy of a Photon of Red Light = 2.83 × 10⁻¹⁹ Joules

As 4.96 × 10⁻¹⁹ Joules is > 2.83 × 10⁻¹⁹ Joules

The Energy of Photon of Violet Light is Greater than Red light Photon

Quick Approach :

Energy of a Photon is given by : E = hc/λ

From the above Expression we can say that Energy of Photon is Inversely Proportional to Wavelength of Photon.

Higher the Wavelength of Photon ----> Lower the Energy of Respective Photon

Given Wavelength of Red Light Photon (7000 A°) is Greater than Wavelength of Violet Light Photon (4000 A°)

Energy of Red Light Photon will be Less than Energy of Violet Light Photon.