A point source of light is placed at the focus of a concave mirror. Consider only paraxial rays. The shapes of the wavefronts of incident and reflected lights respectively are:
A point source of light is placed at the focus of a concave mirror. Consider only paraxial rays. The shapes of the wavefronts of incident and reflected lights respectively are:
spherical spherical
spherical, planar
spherical, cylindrical
planar, spherical
The Correct Option is B
Solution and Explanation
The correct option is: (B): spherical, planar.
When a point source of light is positioned at the focus of a concave mirror, paraxial rays that are nearly parallel to the principal axis are considered. In this scenario:
Incident Light Wavefronts: The incident light rays, originating from the point source at the focus, diverge after reflection from the mirror. Due to the geometry of a concave mirror, the wavefronts of the incident light are spherical. This is because the light rays converge toward the focal point before striking the mirror.
Reflected Light Wavefronts: The reflected light rays follow the principle of reflection, where the angle of incidence equals the angle of reflection. Since paraxial rays are considered, the angles are small. As a result, the reflected light rays are parallel or nearly parallel to the principal axis. Consequently, the wavefronts of the reflected light are planar or nearly planar.
In summary, the incident light wavefronts are spherical, and the reflected light wavefronts are planar for a point source of light placed at the focus of a concave mirror.
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Concepts Used:
Electrostatic Potential
The electrostatic potential is also known as the electric field potential, electric potential, or potential drop is defined as “The amount of work that is done in order to move a unit charge from a reference point to a specific point inside the field without producing an acceleration.”
SI Unit of Electrostatic Potential:
SI unit of electrostatic potential - volt
Other units - statvolt
Symbol of electrostatic potential - V or φ
Dimensional formula - ML2T3I-1
Electric Potential Formula:
The electric potential energy of the system is given by the following formula:
U = 1/(4πεº) × [q1q2/d]
Where q1 and q2 are the two charges that are separated by the distance d.