Bihar Board Class 12 (Science) Ray Optics and Optical Instruments — practice questions
101 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice Bihar Board Class 12 (Science) Ray Optics and Optical Instruments in the app →Snell's law of refraction at the boundary between two media of refractive indices $n_1$ and $n_2$ statesThe relationship between the focal length $f$ and the radius of curvature $R$ for a SPHERICAL MIRROR isThe POWER of a lens (in diopters, D) is defined asTwo thin lenses of powers $+5\,\text{D}$ and $-3\,\text{D}$ are placed in CONTACT. The total power of the combA converging lens of focal length $20\,\text{cm}$ produces a real image at $30\,\text{cm}$ from the lens. The When light travels from one medium to another, which property of the wave REMAINS UNCHANGED?An object is placed at the FOCUS of a concave mirror ($u = f$, both negative). The image forms atThe phenomenon by which the apparent position of a star near the horizon appears slightly higher than its actuThe mirror equation relates u, v and f asThe power P of a lens of focal length f (in metres) is given byAn object is placed 30 cm from a concave mirror of focal length 20 cm. The image distance isRefractive index of water with respect to air is 4/3. The critical angle for a water–air interface is approximA convex lens of focal length 20 cm is placed in contact with a concave lens of focal length 25 cm. The power Light passes from air (n=1) into glass (n=1.5) at an incidence angle of 60°. Using Snell's law, the angle of rFor a thin prism of small refracting angle A and refractive index n, the deviation δ is approximatelyAn astronomical telescope in normal adjustment has an objective of focal length 100 cm and an eyepiece of focaThe apparent depth of an object lying at the bottom of a pool of water (n = 4/3) is, in terms of its real deptA thin prism of refracting angle 5° is made of glass with n = 1.5. The deviation δ of a light ray passing throTwo thin convex lenses, each of focal length 20 cm, are placed coaxially 10 cm apart in air. The equivalent foIn Cartesian convention, a concave mirror has a focal length that isWhich spherical mirror has a positive focal length in Cartesian convention?A spherical mirror has a radius of curvature of 30 cm. Its focal length is aboutDistances measured along the direction of the incident light are taken asFrom which point on a spherical mirror are all distances measured?Heights measured downwards from the principal axis are taken asWhich equation connects u, v and f for a spherical mirror?The thin lens formula relating u, v and f isThe lens maker's formula makes 1/f proportional toA diverging lens has a focal length that isA concave lens has a focal length of 50 cm. Its power isThin lenses of power +3 D and -1 D touch each other. Combined power isTwo thin lenses of focal lengths 20 cm and 30 cm are in contact. Combined focal length?Splitting of light into its constituent colours is calledA magnifier of f = 5 cm is adjusted for viewing at 25 cm. Magnifying power?A magnifier of f = 10 cm is set for relaxed viewing at infinity. Its magnification isThe least distance of distinct vision is taken asTotal magnifying power of a compound microscope isA telescope has fo = 100 cm and fe = 1 cm. Its magnifying power isTube length of an astronomical telescope in normal adjustment isA 100x telescope views stars 1 arcminute apart. They seem separated by aboutWhich telescope adds inverting lenses so the object looks erect?Light gathering power of a telescope depends on its objective'sBetter resolving power in a telescope needs an objective with largerTelescopes with mirror objectives are calledWhich defect is absent when a mirror serves as the objective?A Cassegrain telescope uses which secondary mirror?Each of the Keck telescopes in Hawaii has a reflector about how wide?Giant lens objectives are rarely built because they areA telescope mirror is easier to support than a lens because it can be heldMain drawback of putting the eyepiece at a reflector's focus isThe angle of incidence that gives a 90° angle of refraction is theGlass of refractive index 2 lies in air. Its critical angle isA material has a critical angle of 45° in air. Its refractive index isAn optical fibre works on the principle ofIn an optical fibre, the core compared with the cladding hasPrisms that bend light by 90° via total reflection need a critical angle belowAt minimum deviation, the ray inside a prism isAt minimum deviation in a prism, the angles satisfyA 60° prism has minimum deviation of 30°. Its refractive index is aboutA thin prism of angle 4° and n = 1.5 deviates light by aboutApart from minimum deviation, each deviation in a prism occurs forA simple microscope is a converging lens ofFor relaxed viewing at infinity, a magnifier's object is placedThick lenses give coloured images because ofThe laws of reflection hold at each point ofFor a spherical mirror the normal at the point of incidence lies along theThe geometric centre of a spherical lens is called itsThe line joining a mirror's pole and centre of curvature is itsFor a given pair of media, the ratio sin i to sin r isWhich lens aberration arises from variation of refractive index with wavelength?A comet-shaped smear of an off-axis point source is calledWhich aberration arises because spherical surfaces are not an ideal lens shape?Automatic wiper rain sensors rely on which principle?Which retinal cells respond to low intensity light?Which structure controls the lens shape for near focus?The jelly-like substance behind the eye lens is theA tank is 12 cm deep with water (n = 4/3). Seen from directly above, the bottom appears at a depth of:A ray crosses a rectangular glass slab. The emergent ray is:Turpentine is lighter than water yet bends light more. So optical density:Light bends towards the normal on entering a medium that is:Glass has n = 1.5 and water has n = 4/3, both relative to air. The index of glass relative to water is:A bent optical fibre still carries light along its length because:Optical fibres are used as a light pipe in medicine to:Besides turning light by 90 degrees, a total reflection prism can:Which medium has the smallest critical angle with respect to air?A thin prism of glass with n = 1.6 gives a deviation of 3 degrees. Its refracting angle is:A lens has a power of -2.5 D. Its focal length is:One dioptre is equal to:Lenses of +2 D, +3 D and -1.5 D are placed in contact. The total power is:Two identical convex lenses of focal length 30 cm touch each other. Their combined focal length is:Dispersion of light means:A microscope objective magnifies 10 times; eyepiece f = 5 cm (near point). Total:You cannot see your face in a book page mainly because it:A concave mirror has f = -15 cm and an object stands 30 cm away. Reflected rays meet at:For an object 10 cm from a concave mirror of radius 40 cm, reflected light seems to come from:A convex lens has f = 12 cm and an object is 18 cm away. The magnification is:A diverging lens of f = -20 cm is 20 cm from an object. Rays appear to diverge from:An equiconvex lens of glass (n = 1.5) has surfaces of radius 30 cm. Its focal length is:A glass lens sits in a liquid of the same refractive index. It then acts like:The refractive index of a pair of media depends on the:In the Cartesian convention, heights above the principal axis are taken as: