1. A student has focused the image of a candle flame on a white screen using a concave mirror. The
    situation is as given below:
    Length of the flame =1.5 cm focal length of the mirror=12 cm.
    Distance of flame from the mirror =18 cm.
    If the flame is perpendicular to the the principal axis of the mirror then calculate
    a)distance of the image from the mirror
    b) length of the image.

Verified Answer :

Certainly! Let's solve the problem step by step.

### Given Data:
- Length of the flame (\(\(h\)\)) = 1.5 cm
- Focal length of the mirror (\(\(f\)\)) = 12 cm
- Distance of the flame from the mirror (\(\(u\)\)) = 18 cm

### Required:
a) Distance of the image from the mirror (\(\(v\)\))
b) Length of the image (\(\(h'\)\))

### Step 1: Use the Mirror Formula to Find the Image Distance (\(\(v\)\))
The mirror formula for a concave mirror is:
\(\[ \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \]\)

Rearranging for \(\( \frac{1}{v} \)\):

\(\[ \frac{1}{v} = \frac{1}{f} - \frac{1}{u} \]\)

Substitute the known values into the formula:

\(\[ \frac{1}{v} = \frac{1}{12} - \frac{1}{18} \]\)

Find a common denominator to simplify the fractions:

\(\[ \frac{1}{v} = \frac{3 - 2}{36} \]\)
\(\[ \frac{1}{v} = \frac{1}{36} \]\)

Therefore, the image distance \(\(v\)\) is:

\(\[ v = 36 \text{ cm} \]\)

### Step 2: Use the Magnification Formula to Find the Image Length (\(\(h'\)\))
The magnification (\(\(m\)\)) of a mirror is given by:

\(\[ m = -\frac{v}{u} \]\)

Where \(\(m\)\) is also the ratio of the image height (\(\(h'\)\)) to the object height (\(\(h\)\)), so:

\(\[ m = \frac{h'}{h} \]\)

Substitute the values of \(\(v\)\) and \(\(u\)\) into the magnification formula:

\(\[ m = -\frac{36}{18} \]\)
\(\[ m = -2 \]\)

So, the magnification (\(\(m\)\)) is \(\(-2\)\).

Using the magnification to find the image length (\(\(h'\)\)):

\(\[ h' = m \times h \]\)
\(\[ h' = -2 \times 1.5 \]\)
\(\[ h' = -3 \text{ cm} \]\)

The negative sign indicates that the image is inverted relative to the object.

### Final Answers:
a) The distance of the image from the mirror is \(\(36 \text{ cm} \)\).

b) The length of the image is \(\(3 \text{ cm}\)\) (inverted).