Ray Optics PYQs Set 5 (PDF)

Set 5 of 18 · Questions 121-150 of 521

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 5 (Q121-150)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
121. $A point object is moving at a constant speed of 1 m s^{- 1} along the principal axis of a conver lens of focal length 10 cm . The speed of the image is also 1 m s^{- 1}, when the object is at cm from the optic centre of the lens.$ (1) $10$ (2) $15$ (3) $20$ (4) $5$ 122. $A person cannot see distinctly at the distance less than one metre. Calculate the power of the lens that he should use to read a book at a distance of 25 cm$ (1) $+ 3.0 D$ (2) $+ 0.125 D$ (3) $- 3.0 D$ (4) $+ 4.0 D$ 123. $Two thin lenses of focal lengths f_{1} and f_{2} are in contact and coaxial. The power of the combination is$ (1) $\frac{f _{1} + f _{2}}{2}$ (2) $\frac{f _{1} + f _{2}}{f _{1} f _{2}}$ (3) $\frac{f _{1}}{f _{2}}$ (4) $.$ 124. $A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black, then$ (1) $the image shifts upward$ (2) $the image shifts downward$ (3) $the intensity of the image decreases$ (4) $the intensity of the image increases$ 125. $An object is at a distance of 20 m from a convex lens of focal length 0.3 m . The lens forms an image of the object. If the object moves away from the lens at a speed of 5 m / s, the speed and direction of the image will be:$ (1) $2.26 \times 10^{- 3} m / s away from the lens$ (2) $0.92 \times 10^{- 3} m / s away from the lens$ (3) $3.22 \times 10^{- 3} m / s towards the lens$ (4) $1.16 \times 10^{- 3} m / s towards the lens$ 126. $A ray of light suffers a minimum deviation when incident on an equilateral prism of refractive index . The angle of incidence is$ (1) $30^{\circ}$ (2) $45^{\circ}$ (3) $60^{\circ}$ (4) $50^{\circ}$ 127. $A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of curvature of a surface of a planoconvex lens made of the same material with power 1.5 P is$ (1) $\frac{3 R}{2}$ (2) $2 R$ (3) $\frac{R}{3}$ (4) $\frac{R}{2}$ 128. $A parallel beam of light of wavelength is incident normally on a narrow slit. A diffraction pattern formed on a screen placed perpendicular to the direction ofthe incident beam. At the second minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is$ (1) $2 π$ (2) $3 π$ (3) $4 π$ (4) $π λ .$ 129. $For the thin convex lens, the radii of curvature are at 15 cm and 30 cm respectively. The focal length the lens is 20 cm. The refractive index of the material is :$ (1) $1.2$ (2) $1.8$ (3) $1.5$ (4) $1.4$ 130. $For a concave mirror of focal length 20 cm, If the object is at a distance of 30 cm from the pole, the nature of image and magnification will be-$ (1) $Real and - 2$ (2) $Virtual and - 2$ (3) $Real and + 2$ (4) $Virtual and + 2$ 131. $A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be$ (1) $convex, + 2.25 dioptre$ (2) $concave, - 0.25 dioptre$ (3) $concave, - 0.2 dioptre$ (4) $convex, + 0.15 dioptre.$ 132. $Refractive index of a medium is . If the angle of incidence is twice that of the angle of refraction, then the angle of incidence is$ (1) $cos^{- 1} (\frac{μ}{2})$ (2) $sin^{- 1} (\frac{μ}{2})$ (3) $2 cos^{- 1} (\frac{μ}{2})$ (4) $sin^{- 1} (μ)$ 133. $Which of the following statement is correct ?$ (1) $In primary rainbow, observer sees red colour on the top and violet on the bottom$ (2) $In primary rainbow, observer sees violet colour on the top and red on the bottom$ (3) $In primary rainbow, light wave suffers total internal reflection twice before coming out of water drops$ (4) $Primary rainbow is less bright than secondary rainbow.$ 134. $A girl of height 150 cm with her eye level at 140 cm stands in front of plane mirror of height 75 cm fixed to a wall. The lower edge of the mirror is at a height of 85 cm above her feet level. The height of her image the girl can see in the mirror is$ (1) $130 cm$ (2) $140 cm$ (3) $120 cm$ (4) $150 cm$ 135. $A screen is placed 90 cm from an object. The image is formed by using a convex lens twice on the screen by putting the lens at two different locations separated by 20 cm . The focal length of the lens is approximately equal to$ (1) $21.38 cm$ (2) $30.0 cm$ (3) $35.0 cm$ (4) $24 cm$ 136. $In total internal reflection when the angle ofincidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction7.$ (1) $9 0^{o}$ (2) $18 0^{o}$ (3) $0^{o}$ (4) $equal to angle of incidence$ 137. $The radius of curvature of a convex lens is , for each surface. Its refractive index is 1.5 . Its focal length is$ (1) $40 cm$ (2) $20 cm$ (3) $80 cm$ (4) $30 cm$ 138. $An equiconvex lens made of glass of refractive index has focal length in air. It is completely immersed in water of refractive index . The percentage change in the focal length is$ (1) $400 % increase$ (2) $300 % decrease$ (3) $400 % decrease$ (4) $300 % increase$ 139. $A linear object of height 10 cm is kept in front of a concave mirror of radius of curvature 15 cm, at a distance of 10 cm . The image formed is$ (1) $magnified and erect$ (2) $magnified and inverted$ (3) $diminished and erect$ (4) $diminished and inverted.$ 140. $Which one of the following phenomena is not explained by Huygen’s construction of wavefront?.$ (1) $Refraction$ (2) $Reflection$ (3) $Diffraction$ (4) $Origin ofspectra$ 141. $Two convex lenses of focal lengths f_{1} and f_{2} form images with magnification m_{1} and m_{2}, when used individually for an object kept at the same distance from the lenses. Then, f_{1} / f_{2} is$ (1) $\frac{m _{1} ( 1 - m _{1} )}{m _{2} ( 1 - m _{2} )}$ (2) $\frac{m _{1} ( 1 - m _{2} )}{m _{2} ( 1 - m _{1} )}$ (3) $\frac{m _{2} ( 1 - m _{1} )}{m _{1} ( 1 - m _{2} )}$ (4) $\frac{m _{2} ( 1 - m _{2} )}{m _{1} ( 1 - m _{1} )}$ 142. $Which of the following is not due to total internal reflection?.$ (1) $Working of optical fibre$ (2) $Difference between apparent and real depth of a pond$ (3) $Mirage on hot summer days$ (4) $Brilliance of diamond$ 143. $According to Newton's corpuscular theory the speed of light is$ (1) $same in all the media$ (2) $lesser in rarer medium$ (3) $lesser in denser medium$ (4) $independent of the medium.$ 144. $The angle of minimum deviation for an incident light ray on an equilateral prism is equal to its refracting angle. The refractive index of its material is$ (1) $\frac{1}{2}$ (2) $3$ (3) $\frac{3}{2}$ (4) $\frac{3}{2}$ 145. $A convex lens of focal length 30 cm is placed in contact with a concave lens of focal length 20 cm. An object is placed at 20 cm to the left of this lens system. The distance of the image from the lens in cm is _______.$ (1) $\frac{60}{7}$ (2) $15$ (3) $45$ (4) $30$ 146. $A ray of light is incident at an angle of incidence, i, on one face of prism of angle A (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is μ, the angle of incidence i, is nearly equal to :$ (1) $μA$ (2) $A/3μ$ (3) $A/μ$ (4) $A/2μ$ 147. $Pick out the WRONG statement from the following.$ (1) $Lateral shift increases as the angle of incidence increases.$ (2) $Lateral shift increases as the value of refractive index increases.$ (3) $Normal shift decreases as the value of refractive index increases.$ (4) $Both normal shift and lateral shift are directly proportional to the thickness of the medium.$ 148. $An object is placed at 20 cm in front of a concave mirror produces three times magnified real image. What is focal length of the concave mirror?$ (1) $10 cm$ (2) $15 cm$ (3) $7.5 cm$ (4) $6.6 cm$ 149. $A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is and the refractive index of the lens material is , then the focal length ofthe lens (in ) is$ 150. $A parallel beam of light travelling in air (refractive index 1.0) is incident on a convex spherical glass surface of radius of curvature 50 cm . Refractive index of glass is 1.5 . The rays converge to a point at a distance from the centre of the curvature of the spherical surface. The value of is cm .$