Question

Q. 38 of 80
Mark for review
☆
A dentist holds a concave
mirror with radius of
curvature 4 cm at a distance
of 1.5 cm from a filling in a
tooth. What is the
magnification of the image
of the filling?​

Answer 1

Answer:

Magnification =  4

Explanation:

We are given that the radius of curvature of concave mirror is 4

First we calculate the focal length;

Focal length = Radius / 2

F = 4 / 2 = 2

Now we know that u is 1.5 cm

Using the below formula;

1/f  = 1/u + 1/v  

1/2 = 1/1.5 + 1/v  

0.5 – 0.66 = 1/ v

1/ V = - 0.1667

V = - 6

Magnification =  - v / u

Magnification =  - (-6) / 1.5

Magnification =  4

Answer 2

The  magnification of the image  of the filling is 4

Given:

Radius of  curvature = 4 cm

Mirror distance = 1.5 cm = Image distance

Explanation:

The focal length is given by the formula:

Focal length = Radius of  curvature ÷ 2

Focal length = 4/2

∴ Focal length = 2 cm

The mirror equation is given as:

1/f = 1/u + 1/v

Where,

f = Focal length = 2 cm

u = Image distance = 1.5 cm

v = Object distance = ?

1/2 = 1/1.5 + 1/v

∴ v = - 6

Now, the magnification is given by the formula:

m = -v/u

On substituting the values, we get,

m = 6/1.5

∴ m = 4