Class 7 Light - Reflection of Light

Q: 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.

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

Q: Why is AMBULANCE written laterally inverted on an Ambulance van?

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.

Q: A man stands 10 m in front of a large plane mirror. How far must he walk before he is 5 m away from his image?

Initially, the distance between the man and the mirror is 10m. So, the distance between man and image is 10+10=20m. Distance between the man and his image is 5m when the man is 2.5m away from the mirror.Therefore, he has to walk 10m -2.5m=7.5m towards the mirror.

Q: Write three characteristics of image formed by a plane mirror ?

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

Q: Choose the alternative which closely resembles the mirror image of the given combination.

The mirror image is laterally inverted.Answer-(D)

Q: Define Lateral inversion.

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

Q: Boojho planned a activity to observe an object A through pipes as shown in Fig. 16.8, so that he could see objects which he could not directly see. (a) How many mirrors should he use to see the objects?(b) Indicate the positions of the mirrors in the figure.(c) What must be the angle with respect to the incident light at which he should place the mirrors?(d) Indicate the direction of rays in the figure.(e) If any of the mirrors is removed, will he be able to see the objects?

(a) Three Plane mirrors(b) As shown in fig-(c) 45°(d) As shown in figure-(e) No, he will not be able to see the objects.

Q: Image formed by a plane mirror is

Answer is B.The image formed by a plane mirror is always virtual (meaning that the light rays do not actually come from the image), upright, and of the same shape and size as the object it is reflecting. A virtual image is a copy of an object formed at the location from which the light rays appear to come.To summarize, the image formed by plane mirrors are,1. Virtual 2. Behind the mirror 3. Erect (means not inverted) 4. Same size as the object 5. At same distance from the mirror as the object is from the mirror.

Q: An object is placed at a distance of \$0.25m\$ in front of a plane mirror. The distance between the object and the image is:

For reflection from a plane mirror, distance between object and mirror \$=\$ distance between mirror and the image\$=0.25m\$So, distance between object and image\$=\$ (distance between object and mirror) \$+\$ (distance between mirror and image) \$=(0.25+0.25)m=0.5m\$