Which mirror is used as a rear view mirror why justify your answer by drawing a ray diagram

If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?

A convex mirror always produces an erect and diminished image of the object placed in front of it irrespective of the position of the object.

Consider a case in which an object is placed anywhere between pole (P) and infinity in front of a convex mirror. The ray diagram is as shown:-

A virtual, erect and diminished image will be formed behind the mirror between the pole (P) and focus (F) of the mirror.

As a convex mirror gives a wide field of view, it is used as a rear view mirror in vehicles.

It enables the driver to view a much larger area of the traffic behind. It is also used as shop security mirrors.

Is there an error in this question or solution?

(i) Convex mirrors are used as rearview mirrors.

The two reasons are given below:

1. They always formed a virtual and erect image of the object.

2. They have a wider field of view as they produce diminished size of the image.

(ii) Concave mirrors are used as shaving mirrors.

The two reasons are given below:

1. The image formed is magnified in size, which enables a person to see the minute details of the face in the mirror.

2. When the object is placed close to the mirror, the image formed is virtual and erect.

Explanation

A convex mirror, also known as a diverging mirror, as it is curved outward in the middle and when light strikes the reflective surface of the mirror, it diverges light rays. It always forms virtual, erect, and diminished images irrespective of the distance between the object and the mirror.

It is used in rearview mirrors of vehicles, shop security mirrors or traffic mirrors.

A concave mirror, also known as a converging mirror, as it is curved inward in the middle and when light strikes the reflective surface of the mirror, it converges light rays. Depending on the position of the object with respect to the mirror, the types of images it forms are real, inverted as well as virtual and erect image, also the size of the images formed are magnified, diminished as well as the same size as that of the object.

It is used in solar furnaces, torches, dentist mirrors, shaving and makeup mirrors.

Mention the types of mirrors used as (i) rear view mirros, (ii) shaving mirrors. List two reasons to justify you answers in each case.

Asked by Topperlearning User | 21 Jul, 2017, 10:35: AM

(i) Rear view mirrors: Convex mirrors are used.

Reason: (a) They produce virtual and erect image of the objects.

(b) They have a wider field of view as they are curved outwards.

(ii) Shaving mirrors: Concave mirros are used.

Reason: (a) Image formed is magnified so as to see the details of the object clearly.

(b) Image formed is virtual and erect when the object is placed close to the mirror.

Answered by | 21 Jul, 2017, 12:35: PM

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An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.

Converging lens means a convex lens. As the distances given in the question are large, so we choose a scale of 1: 5, i.e., 1 cm represents 5 cm. Therefore, on this scale 5 cm high object, object distance of 25 cm and focal length of 10 cm can be represented by 1 cm high, 5 cm and 2 cm lines respectively. Now, we draw the ray diagram as follows:(i) Draw a horizontal line to represent the principal axis of the convex lens.(ii) Centre line is shown by DE.(iii) Mark two foci F and F' on two sides of the lens, each at a distance of 2 cm from the lens.(iv) Draw an arrow AB of height 1 cm on the left side of lens at a distance of 5 cm from the lens.(v) Draw a line AD parallel to principal axis and then, allow it to pass straight through the focus (F') on the right side of the lens.(vi) Draw a line from A to C (centre of the lens), which goes straight without deviation.(vii) Let the two lines starting from A meet at A'.(viii) Draw AB', perpendicular to the principal axis from A'.(ix) Now AB', represents the real, but inverted image of the object AB.(x) Then, measure CB' and A'B'. It is found that CB' = 3.3 cm and A'B' = 0.7 cm.

(xi) Thus the final position, nature and size of the image A'B' are: (a) Position of image A'B' = 3.3 cm × 5 = 16.5 cm from the lens on opposite side. (b) Nature of image A’B’: Real and inverted.