# CBSE Solutions for Class 10 Physics

#### Select CBSE Solutions for class 10 Subject & Chapters Wise :

Power of convex lens is positive and concave lens is ………………

negative

……………. is ratio of height of image to height of object

Magnification

The dentists use ………….. mirror to see large images of teeth of patients.

concave

When rays of light after reflection meet a point ………….. image is formed.

real

According to laws of reflection, the angle of incidence is equal to angle of ……………..

reflection

When light falls on a surface and bounces back to the medium, the phenomena is called ……………..

reflection

No matter how far you stand from a spherical mirror, your image appears erect. The mirror may be ………. .

plane or convex mirror

A ………. mirror is used as a head mirror by the doctors to concentrate light on the body parts to be examined

concave

A positive sign in the value of magnification indicates that the image is ……….

virtual

A ………. lens will always give a virtual, erect and diminished image, irrespective of the position of the object.

concave

The SI unit of power is ………. .

dioptre

Power of’ a lens is the ………. of its focal length.

reciprocal

The speed of light in vacuum is ………. .

3 x 108 m/s

Light shows the phenomena of reflection, refraction and ………. .

dispersion

A ray of light travelling in air enters obliquely into water. Does the light ray bends towards the normal or away from the normal? Why?

The light ray bends towards the normal. When a light ray enters from an optically rarer medium (which has low refractive index) to an optically denser medium (which has a high refractive index), its speed slows down and bends towards the normal. As water is optically denser than air, a ray of light entering from air into water will bend towards the normal.

The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

Radius of curvature (R) = 20 cm

Radius of curvature of the spherical mirror = 2 × Focal length (f)

R = 2f

f= R/2 = 20 / 2 = 10

Therefore, the focal length of the spherical mirror is 10 cm.

Why do we prefer a convex mirror as a rear-view mirror in vehicles?

Convex mirror is preferred as a rear-view mirror in cars and vehicles as it gives a wider field of view, which helps the driver to see most of the traffic behind him. Convex mirrors always form an erect, virtual, and diminished image of the objects placed in front of it.

Find the focal length of a convex mirror whose radius of curvature is 32 cm.

Radius of curvature (R) = 32 cm

Radius of curvature = 2 × Focal length (f)

R= 2f

f = R/2 = 32/2 = 16

Therefore, the focal length of the given convex mirror is 16 cm.

A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?

Magnification produced by a spherical mirror:

Define the principal focus of a concave mirror.

Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is called the principal focus of the concave mirror.

Name the mirror that can give an erect and enlarged image of an object.

The mirror that can give an erect and enlarged image of an object is Concave Mirror.

Object distance (u) = – 10 cm

v = 3 × (- 10) = – 30 cm

Therefore, the negative sign indicates that an inverted image is formed in front of the given concave mirror at a distance of 30 cm.

 The deviation of light ray from its path when it travels from one medium to another Converging lens Magnification of plane mirror Refraction Convex lens is also known as One

a. Refraction
b. One
c. Converging lens

 Column I Column II (a) Mirror having magnification always equal to one (m = 1) (i) concave mirror (b) Mirror used to concentrate sunlight in reflecting solar cooker (ii) refraction (c) Image can be obtained on screen (iii) plane mirror (d) Bottom of a tank containing water appears to be raised due to (iv) convex lens (e) The lens having power – 2D (v) real image (f) The lens which is thicker at middle as compared to edges (vi) concave lens (g) Mirror used as rear-view mirror in vehicles (vii) convex mirror

 Column I Column II (a) Mirror having magnification always equal to one (m = 1) (iii) plane mirror (b) Mirror used to concentrate sunlight in reflecting solar cooker (i) concave mirror (c) Image can be obtained on screen (v) real image (d) Bottom of a tank containing water appears to be raised due to (ii) refraction (e) The lens having power – 2D (vi) concave lens (f) The lens which is thicker at middle as compared to edges (iv) convex lens (g) Mirror used as rear-view mirror in vehicles (vii) convex mirror