Rotation of reflected ray

Physics Assignment Help Online

Rotation of reflected ray If a fixed ray is incident on a plane mirror at an angle i the angle of reflection is also equal to i, and so the angle between the two rays will be 2i. Suppose now that the mirror is rotated though an angle 8. The angle of incidence will increase by 8, and […]

Diffuse reflection

Physics Assignment Help Online

Diffuse reflection Mirrors and sheets of glass are highly polished surfaces. The surfaces of most objects, however, are found to have tiny irregularities when they are examined under a microscope. Paper is an example. Thus when a parallel beam of light falls on such a surface the individual rays strike it at different angles of incidence. The […]

Pepper’s ghost

Physics Assignment Help Online

Pepper’s ghost This method of producing the illusion of a ghost on the theatrical stage was invented by John Pepper, director of the Royal Polytechnic Institution, London, in the mid nineteenth century. A large sheet of polished plate glass placed diagonally across the stage acts as a mirror, but at the same time permits objects on the […]

The periscope

Physics Assignment Help Online

The periscope The simple periscope consists of two plane mirrors, fixed facing one another at an angle of 45° to the line joining them. The user is enabled to see over the heads of a crowd or over the top of any obstacle. The upper mirror Ml produces an image II, which may then be regarded ,as an […]

Parallel mirrors

Physics Assignment Help Online

Parallel mirrors An infinite number of images are formed of an object placed between two parallel mirrors. These all lie on a straight line through the object perpendicular to the mirrors (Fig. 21.17). The positions of the images may be found by the usual construction, remembering that each image seen in one mirror will act as a virtual object […]

The kaleidoscope

Physics Assignment Help Online

The kaleidoscope The kaleidoscope consists of two strips of plane mirror M1 and M2 about 15 em long, placed at an angle of 60° inside a tube (Fig. 21.16). At the bottom of the tube is a ground-glass plate to admit light, on which is scattered small pieces of brightly coloured glass. These pieces of coloured glass […]

Looking into a plane mirror

Physics Assignment Help Online

Looking into a plane mirror We were, of course, already familiar with some of the above facts from our everyday experience with mirrors. Looking into a mirror, we see an image of the face situated apparently behind the mirror. If we now move backwards the image will recede so that it is always the same distance behind […]

Parallax in pointer instruments

Physics Assignment Help Online

Parallax in pointer instruments Electrical and other instruments which have a pointer moving above a scale are liable to parallax errors if the eye is not vertically above the pointer when taking a reading. Good-class instruments have a plane mirror on the scale. Parallax error is avoided if the eye is positioned so that, when taking a reading, […]