Question

a spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror write the type of mirror find the distance of the image from the object write the focal length of the mirror show the image form in the case

Answer 1

Answer:

The rings are formed due to path difference which is equal to the length traversed by a ray of light in the air between the lower surface of the lens and the glass beneath it. Using a bio convex lens instead of plano convex will still form the rings of the same respective radii as if we had used a plano convex lens of same curvature. The image may appear somewhat less clear though, due to some change in direction of rays from the upper surface of the lens

Answer 2

Answer:

1. It is a concave mirror.

2. Distance of the image from the object is zero

3. Focal length=-25cm.

Explanation:

Given:

Magnification (m) = -1.

Image distance(v)= 50 cm= -50cm (by sign convention).

To Determine:

1. Type of mirror

2. Distance of the image from the object

3. Focal length.

1. Negative sign of magnification denotes that the image formed is inverted. Also, since the object is obtained on a screen, So, it is real. This means that the object is real and inverted. Hence, the given mirror is a concave mirror.

2. By definition of magnification we get:

$m = - \frac{v}{u}$

Putting the values, we get:

$- 1 = - \frac{ - 50}{u} \\ u = - 50.$

Object distance (u)= -50 cm.

Therefore, distance of the image from the object= 0(since the object and the image are at the same distance from the pole).

3. By mirror formula we get:

$\frac{1}{f } = \frac{1}{v} + \frac{1}{u} \\ \frac{1}{f} = \frac{1}{ - 50} + \frac{1}{ - 50} = \frac{ - 1}{25 } \\ f = - 25.$

Focal length (f)=-25cm.