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Two plane mirrors each 1.6 m long, are f...

Two plane mirrors each 1.6 m long, are facing each other. The distance between the mirrors is
20 cm. A light incident on one end of one of the mirrors at an angle of incidence of `30^(@)`. How many times is the ray reflected before it reaches the other end?

A

There are 15 reflections counting the first one

B

There are 13 refelections counting the first one

C

There are 12 reflections counting the first one

D

None of the above

Text Solution

Verified by Experts

(a) From the figure, given in question,
`tan30^(2)=(l_(0))/dimpliesl_(0)=d tan 30^(@)=20/(sqrt(3)`
`:.` Number of reflections `=[L/(l_(0))]=[(1.6xx100cm)/(20/(sqrt(3))cm)]=14`
If first reflection is considered then `n=14+1=15`
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Knowledge Check

  • The mirrors each 1.6 m long are facing each other, The distance between the mirrors is 20 cm. A light ray is incident on one end of the mirror at an angle of incidence of 30^(@) . How many times is the ray reflected before it reaches the other end?

    A
    There are 15 reflections counting the first one
    B
    There are 13 reflections counting the first one
    C
    There are 12 reflections counting the first one
    D
    None of the above

  • A ray of light is incident on a plane mirror at an angle of incidence of 30^@ . The deviation produced by the mirror is

    A
    `30^@`
    B
    `60^@`
    C
    `90^@`
    D
    `120^@`

  • If a ray of light is incident on a plane mirror at an angle of incidence of 30^@ , then deviation produced by the mirror is

    A
    `15^@`
    B
    `30^@`
    C
    `60^@`
    D
    `120^@`

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