# Chhattisgarh State Class 7 Science Chapter 12 Solution

Chhattisgarh State Board Class 7 History Chapter 12 Reflection of light Exercise Choose the correct answer, Fill in the blanks, Answer the following question here.

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(1) What is difference between regular and diffused reflection?

 Regular reflection Diffused reflection (1) Regular reflection is a reflection of light ray (1) Diffused reflection is a reflection of parallel ray (2) Light rays fall on polished plane surface (2) Parallel ray fall on an unpolished surfaces (3) Reflected ray are parallel (3) The reflected ray are not parallel (4) They scatter in only one direction (4) They scatter in all direction

(2) Write down the law of reflection.

Answer:- (1) The incident ray, the normal at the point of incidence and reflected ray are in the same plane.

(2) The angle of incidence and the angle of reflection are equal.

(3) What are the features of images formed by the plane mirror?

(1) Plane mirror formed virtual image & upright.

(2) Show same size of image.

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(1) What do you understand by the centre of curvature?

Answer:- The centre of the sphere, of which the given spherical mirror is called it centre of curvature.

(2) Draw a labeled diagram showing the path of the ray reflected from a concave mirror when incident ray is parallel to the principle axes. (3) State two uses of concave mirror:-

(1) Concave mirror use in headlight.

(2) Shaving mirror is a concave mirror.

(4) Which type of lens always form a virtual image?

Answer:- Concave lens always form a virtual image.

(1) Angle of reflection is the –

(i) Angle between the incident ray and the normal drawn on the surface of mirror.

(ii) Angle between the reflected ray and the normal drawn on the surface of mirror.

(iii) Angle between the reflected ray and surface of the mirror.

(iv) Angle between the incident ray and surface of the mirror.

Answer:- (ii) Angle between the reflected ray and the normal drawn on the surface of mirror.

(2) Angle of incident for plane mirror is –

(i) Equal to the angle of reflection

(ii) Less than the angel of reflection

(iii) More than the angle of reflection

(iv) None of these

Answer:- (i) Equal to the angle of reflection.

(3) Nature of the image formed by the plane mirror –

(i) Virtual and straight

(ii) Equal to the object

(iii) Image formed by lateral inversion

(iv) None of these

Answer:- (ii) Equal to the object.

(4) Focal distance of the spherical mirror is –

(i) Equal to the radius of curvature

(ii) Half of the radius of curvature

(iii) One-fourth of the radius of curvature

(iv) None of these

(5) When you drive your vehicle, than to see the object behind us we use –

(i) Concave mirror

(ii) Spherical mirror

(iii) Convex mirror

(iv) None of these

(2) Match the following:-

 (1) Regular reflection (c) (a) Inverted object (2) Diffused reflection (e) (b) Straight image (3) Real image (d) (c) shining surface (4) Virtual image (b) (d) Image of same size (5) Plane mirror (a) (e) Rough surface

(1) What do you understand by lateral inversion?

Answer:- In lateral inversion the left side of the object appears on the right and vice-versa.

(2) What is reflection?

Answer:- When ray of light strike any shining surface they are diverted to a definite direction and this phenomenal is called reflection of light.

(3) How will you find the centre of curvature of a concave mirror?

Answer:- (1) By taking concave mirror on a wooden block with the help of two pins

(2) Making screen of white paper.

(3) Keeping a lighted candle on the block with white paper. And move the block carrying the mirror.

(4) Moving candle forward and backward in such a way that the image of the candle is adjusted at the brightest.

(5) When the position of candle and it image are at centre of curvature of the mirror.

(6) Measure its distance from the mirror.

(4) Write two uses of convex mirror.

(1) Convex mirror use in magnifying glass

(2) In sunglasses convex mirror are called.

(5) Focal distance of concave mirror is 20 cm. Find it radius of curvature.

We know radius of curvature =2xfocal distance

= 2×20

= 40cm

The radius of curvature is 40cm.

= For real and equal image the object should be place at centre of curvature.

(9) Write two differences between convex and concave lens.

Answer:- Difference between convex and concave lens.

(1) Convex lens:- (i) A convex lens is thicker at the centre and thinner at the edges.

(ii) Image formed by a convex lens can be real or virtual.

(2) Concave lens:- (i) A concave lens is thicker at the edges and thinner at the centre.

(ii) Image formed by a concave lens is always virtual, erect.

Updated: January 22, 2021 — 12:52 am