Tag: reflection of light in spherical mirrors

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Questions Related to reflection of light in spherical mirrors

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

The sum of the reciprocals of object distance and image distance is equal to the __________ of a mirror.

  1. focal length

  2. reciprocal of the focal length

  3. radius of curvature

  4. reciprocal of the radius of curvature
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sum of the reciprocals of object distance and image distance is equal to the reciprocal of the focal length of a mirror.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

The relation between $u,\,v\;and\;f$ for a mirror is given by

  1. $f=\displaystyle\frac{u\times v}{u-v}$
  2. $f=\displaystyle\frac{2u\times v}{u+v}$
  3. $f=\displaystyle\frac{u\times v}{u+v}$
  4. $f=\displaystyle\frac{u-v}{u+v}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The relation between $u,\,v\;and\;f$ for a mirror is given by $f=\displaystyle\frac{u\times v}{u+v}$

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

Choose the correct relation between $u,\,v\;and\;r$ for a spherical mirror, where $r$ is radius of curvature.

  1. $r=\displaystyle\frac{2uv}{u+v}$
  2. $r=\displaystyle\frac{2}{u+v}$
  3. $r=\displaystyle\frac{2(u+v)}{(uv)}$
  4. $r=\displaystyle\frac{2uv}{u-v}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The relation between $u,\,v\;and\;f$ for a mirror is given by $f=\displaystyle\frac{u\times v}{u+v}$

so $r=\displaystyle\frac{2u\times v}{u+v}$

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

The ratio of the size of the image to the size of the object is known as :

  1. the focal plane

  2. the transformation ratio

  3. the efficiency

  4. the magnification ratio
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

magnification ratio is given as:

 size or height of image/ size or height of object
substituted with proper sign convention.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. Determine the ratio of the size of the image and the size of object

  1. 2:1

  2. 1:2

  3. 1:1

  4. 4:1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since focal length of concave mirror given is 20cm l. Object is at 40cm distance which means it is at centre of curvature. hence, image will be formed of same size and at centre focus only but real and inverted.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

Linear magnification is

  1. Positive for an inverted image

  2. Negative for an erect image

  3. Zero for an inverted image

  4. Negative for an inverted image
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Linear magnification is given as Image size/ Object size

For calculations of magnification, values of image size and object size are taken with proper sign convention. 
For an inverted image, the image size is taken as negative and hence magnification is negative.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

Distances measured below the principal axis are taken as ........

  1. Positive

  2. Negative

  3. None

  4. Both
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the sign convention followed for mirrors and for lenses, the distances measured above the principal axis are taken as positive and the distances measured below the principal axis are taken as negative.

Hence, the correct answer is OPTION B.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

State whether true or false : 

The magnification produced by a spherical mirror is the ratio of the height of the image to the height of the object.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The magnification is the ratio of height of the image to height of the object. The image is smaller than the object, the magnification will be less than 1. If the image if upside down (inverted) then magnification will be negative.

Multiple choice physics reflection of light in spherical mirrors sign convention for mirrors sign convention for spherical mirrors sign convention for the measurement of distances

A concave mirror forms an erect image of an object placed at a distance of 10 cm from it. The size of the image is double that of the object. Where is the image formed?

  1. 20 cm behind the mirror

  2. 20 cm in front of the mirror

  3. 40 cm behind the mirror

  4. 40 cm in front of the mirror
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since the image is erect , so the magnification ratio must be positive .


$m=2$

also $u=-10cm$

so $m=-\dfrac{v}{u}$

$2=-\dfrac{v}{-10}$ 

$v=20cm$

So the image is virtual and 20 cm from mirror on the other side of the object.