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### LENSES

A lens is made of a transparent material bounded by two spherical surfaces. The surfaces may be both convex, both concave or one convex and one concave etc. For a thin lens, the thickness of the lens is small compared to other dimensions like object distance. Two basic types are: (1) Convex lens – thicker […]

### REFRACTION THROUGH A COMPOUND SLAB

Consider two parallel slabs having refractive index andare kept one above the other. The medium above and below the compound slab is the same. If we consider refraction of light at the interface of ‘a’ and ‘b’, then Now consider refraction of light at the interface of ‘b’ and ‘c’, then Considering refraction of light […]

### REFRACTION IN A PRISM

“A portion of transparent medium bounded by two plane faces, inclined to each other at an angle, is called a prism.” The angle between two refracting faces is called the refracting angle of the prism and the line where two refracting faces meet is called the refracting edge of the prism. Deviation produced by a […]

### EFFECTS OF REFRACTION

EFFECTS OF REFRACTIONS: (a) The apparent depth of objects is lesser in denser media than the actual depth because of this, Swimming pool appears to be much smaller than it actually is. Explanation: Let us consider a object ‘O’ lying at the bottom of a beaker containing water. Two rays ‘OA’ and ‘OB’ from object […]

### REFRACTION AT A SPHERICAL SURFACE

Let us consider, LMN represents a ‘convex’ spherical surface of radius of curvature ‘R’ of refractive index ‘’. Consider a point object ‘O’ on the principal axis situated in an optically rarer medium of . . A ray ‘OA’ incident at an angle ‘i’ is refracted along ‘AI’. Another ray ‘OM’ incident normally on […]

### SIMPLE MICROSCOPE

The visual angle is maximum for unaided eye, when the object is placed at near point. h – Size of the object. D – The least distance for clear vision. This angle can be further increased, if a converging lens of short focal length is placed just in front of the eye. Here, lens acts […]

### COMPOUND MICROSCOPE

CONSTRUCTION OF COMPOUND MISCROSCOPE It consists of two lenses where one lens is compounding the effect of other. The lens close to object is called objective lens (OL) while other lens close to eye is called eye – piece. The objective has a smaller aperture and smaller focal length than those of the eye piece. […]

### COMBINATION OF THIN LENSES IN CONTACT

Consider two lenses A and B of focal length f1 and f2 placed in contact with each other. The image of point object O will be at I1 formed by lens A, which act as a virtual object for second lens B producing the final image at I. since lenses are thin, therefore we assume […]

### PRINCIPAL OF REVERSIBILITY OF LIGHT RAYS

“A ray travelling along the path of the reflected ray is reflected along the path of the incident ray.” In the same way, a refracted ray reversed to travel back along its path will get refracted along the path of the incident ray. Thus the incident and refracted rays are mutually reversible. Now according to […]

### MIRROR FORMULA

The formula which gives relationship between distances of object (u), image distance (v) and the focal length (f) of the mirror is called as mirror formula. Assumptions: (a) Only small aperture mirror must be considered i. e for paraxial rays. (b) The rays of light should not be incident vary obliquely. We assume that P […]

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