Question 1

Boojho and Paheli were given one mirror each by their teacher. Boojho found his image to be erect and of the same size whereas Paheli found her image erect and smaller in size. This means that the mirrors of Boojho and Paheli are, respectively.

Accepted Answer

When the image is erect and of same size as object then it is a plane mirror so Boojho has plane mirrorWhen the image is erect and of small size than object then it is a convex mirror so Paheli has a convex mirror

Question 2

Write three characteristics of image formed by a plane mirror ?

Accepted Answer

The three characteristics of image formed by a plane mirror :Image formed are upright or erect Images formed are virtualImages formed are of the same size as the object

Question 3

Name the type of mirror used in the following situations:a) Headlights of carb) Solar furnaces

Accepted Answer

a) Headlights of car: Type of mirror used is concave as the light of lamp undergoes divergence from reflector surface and cover large  area in the front.b) Solar/rear view of vehicle: It is a convex mirror as it gives diminished, virtual and an erect image of the side or rear with wider field of view. A convex mirror enables driver to view much larger area than would be possible with a plane mirror.c) Solar Furnace: It is a concave mirror. As sun rays after reflection from its surface, get converged at focus with much intense heat.

Question 4

Define Lateral inversion.

Accepted Answer

Lateral inversion - The phenomenon of left side appearing right side andright side appearing left side on reflection in a plane mirror is called lateral inversion

Question 5

Why is AMBULANCE written laterally inverted on an Ambulance van?

Accepted Answer

Ambulance is usually in a hurry. In order to convey the vehicle in front that it is an ambulance, it is written laterally inverted. When the driver of the vehicle in front reads through the rear-view mirror, the Image of this inscription, through lateral inversion, form a right oriented image.

Question 6

Write the differences between convex and concave lens.

Accepted Answer

Convex lens:                                                        Concave lens:(1)The converging lens in air.                           (1)The diverging lens in air.(2)The principal focus behind the lens.          (2)Principal focus is infront of lens.(3)Used as magnifying lens.                            (3)Used as rear view mirror. (4)Forms both real and virtual images.           (4)Only form virtual image.

Question 7

What is a virtual image? Give one situation where a virtual image is formed.

Accepted Answer

The image which cannot be taken on a screen is called virtual image. 
When some object is placed very close to the concave mirror we don't get
 any image on the white screen placed behind the mirror. Such image is 
called virtual image.

Question 8

Give reasons:Concave mirrors are used in solar devices.

Accepted Answer

Concave mirrors are used in solar devices to collect heat and radiations.Heat radiations from the sun coming from infinity are brought to focus by concave mirror in its focal plane.

Question 9

The side mirror of a scooter got broken. The mechanic replaced it with a plane mirror. Mention any inconvenience that the driver of the scooter will face while using it?

Accepted Answer

Mirror used as a side mirror in a scooter is convex mirror. Inconveniences are i) Less area visible on plane mirror as compared to convex mirror. ii) Unable to see traffic behind the vehicle.

Question 10

An object is placed at a distance of  30  cm from a concave lens of focal length  30  cm. (i) Use lens formula to determine the distance of the image from the lens. (ii) List four characteristics of the image (nature position, size, erect/inverted) in this case. (iii) Draw a labelled diagram to justify your answer apart (ii)

Accepted Answer

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