CBSE Class 12 (Science) Ray Optics and Optical Instruments — practice questions
98 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE 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 foA common sign convention lets one formula handle mirrors that are:Rays incident close to the pole and at small angles are called:A parallel beam striking a concave mirror is reflected so that it:A parallel beam striking a convex mirror reflects so that it appears to:The point F on the axis where reflected rays meet is the principal:The plane through F normal to the principal axis is called the:Linear magnification is the ratio of image height to:With proper sign convention, the mirror formulas hold for images that are:Light passing through a prism is studied using a prism that is:The angle at which light leaves the second face of a prism is the angle of:The angle between the emergent ray and the incident ray direction is the:The total deviation through a prism is the sum of deviations at how many faces?Besides bending rays, a prism can also be used to:A simple magnifier is a converging lens of focal length that is:The near point of the eye is taken as a distance of about:The maximum magnification of a simple microscope is described as:For much larger magnification, one uses lenses numbering:In a compound microscope, the lens nearest the object is the:The objective of a compound microscope forms an image that is:A telescope provides angular magnification of objects that are:A mirror used as a telescope objective is free from aberration that is:A reflecting telescope of the folded design is named after:In 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 the