A person 1.8m tall stands 0.75m from a reflecting globe in a garden.
PART A If the diameter of the globe is 16cm , where is the image of the person, relative to the surface of the globe?
PART B How large is the person's image?

Respuesta :

Answer:

1. The image of the person is 1.41 m, virtual and formed at the back of the surface of the globe.

2. The person's image is 3.38 m tall.

Explanation:

From the given question, object distance, u = 0.75 m, object height = 1.8 m, radius of curvature of the reflecting globe, r = 8 cm = 0.08 m.

f = [tex]\frac{r}{2}[/tex] = [tex]\frac{0.08}{2}[/tex] = 0.04 m

1. The image distance, v, can be determined by applying mirror formula:

[tex]\frac{1}{f}[/tex] = [tex]\frac{1}{u}[/tex] + [tex]\frac{1}{v}[/tex]

[tex]\frac{1}{0.04}[/tex] = [tex]\frac{1}{0.75}[/tex] + [tex]\frac{1}{v}[/tex]

[tex]\frac{4}{100}[/tex] - [tex]\frac{75}{100}[/tex] = [tex]\frac{1}{v}[/tex]

[tex]\frac{1}{v}[/tex] = [tex]\frac{4 - 75}{100}[/tex]

  = - [tex]\frac{71}{100}[/tex]

⇒ v = -[tex]\frac{100}{71}[/tex]

      = - 1.41 m

The image of the person is 1.41 m, virtual and formed at the back of the surface of the globe.

2.  [tex]\frac{image distance}{object distance}[/tex] = [tex]\frac{image height}{object height}[/tex]

  [tex]\frac{1.41}{0.75}[/tex] = [tex]\frac{v}{1.8}[/tex]

v = [tex]\frac{2.538}{0.75}[/tex]

  = 3.384

v = 3.38 m

The person's image is 3.38 m tall.