Question

ASsel 24 Define reflection and laws of reflection. Explain why light ray incident along principal axis is reflected back along same path (3 Points)​

Answer 1

Answer:

The reason for light falling on the centre of curvature gets reflected back along the same path is due to the angle of incidence and the angle of reflection lie along the normal for a concave mirror. This point of contact would meet at 90 degrees where the radius of curvature is perpendicular to the tangent making the incident ray and the reflected ray coincide with each other.

The ray of light passes through the centre of curvature of a concave mirror it strikes the mirror along the normal ray, it incidences on to the mirror at an angle of 90 degrees. Hence, the incident ray coincides with the normal.

Therefore, angle of incidence = 0

So, as we know according to the law of reflection

angle of reflection = 0,

Hence, the angle of reflection tends to zero degree, thus the ray of light retraces its path.

Answer 2

Explanation:

given that by giving 10% discount ,the price is Rs. 495,

let original price before discount be x,

therefore,

0.9x = 495,

=> x = 495/0.9,

=> x = 550,which is cost price.

given he sold it for Rs. 660/-,

so gain % = [(660-550)/550]*100,

=> gain % = (110/550)*100,

=> gain % = 20%.