Question

For a science project, you would like to horizontally suspend an 8.5 by 11 inch sheet of black paper in a vertical beam of light whose dimensions exactly match the paper.

If the mass of the sheet is 0.80g , what light intensity will you need?
Express your answer to two significant figures and include the appropriate units.
I = ________.

Answer 1

I = 3.9 x 10⁷ W/m²

Step-by-step explanation:

given,

Sheet of black paper dimension = 8.5 x 11 inch

Area of sheet = 8.5 x 11 = 93.5 inch^2

1 inch =0.0254 m

Area = 0.06032 m²

mass of sheet = 0.80 g

Force = m g = 0.8 x 9.8 x 10⁻³ N

= 7.84 x 10⁻³ N

speed of light = c = 3 x 10⁸ m/s

Using equation

`F = (IA)/(c)`

where I is the intensity of light

`7.84 * 10^(-3) = (I* 0.06032)/(3 * 10^8)`

`2.352 * 10^(6) = I* 0.06032`

`I = (2.352 * 10^(6))/(0.06032)`

I = 3.9 x 10⁷ W/m²

Intensity of the light is equal to I = 3.9 x 10⁷ W/m²