We measure them on the either side of the mirror and not on the side of the normal to the surface of the mirror because, if the mirror or any reflecting surface is bent, then there will be a difference between the angle of incidence and angle reflection which can be avoided by measuring those angles on the either side of the mirror.
The angle of the reflected ray with the normal line to the surface of the mirror is the same as the angle of incidence. Snell's law.
90 degrees (That line is the normal to the mirror.)
If the ray hits the mirror at an angle of 30 degrees with the mirror surface, the complementary angle that the ray makes with the normal (perpendicular) to the mirror at the point of incidence is (90 - 30) = 60 degrees and since angle of incidence is equal to angle of reflection in a plane mirror, the angle of reflection is 60 degrees.
The angle of reflection (θr) off a planar surface (eg. mirror) is equal to the angle of incidence (θi) on that surface. They are measured with respect to the normal, which is an imaginary line drawn perpendicular to the surface. Or, in simpler terms, the angle of reflection is the same as the angle of incidence.
We measure them on the either side of the mirror and not on the side of the normal to the surface of the mirror because, if the mirror or any reflecting surface is bent, then there will be a difference between the angle of incidence and angle reflection which can be avoided by measuring those angles on the either side of the mirror.
The angle between the mirror and the normal is called the angle of incidence. It is the angle formed between the incident ray (incoming light ray) and the normal (a line perpendicular to the surface of the mirror) at the point of incidence.
When a light ray is directed at a mirror, it reflects off the mirror's surface. The angle of incidence (the angle between the incoming light ray and the normal to the mirror's surface) will be equal to the angle of reflection (the angle between the reflected light ray and the normal). This follows the law of reflection.
When a ray of light is directed at a mirror, it will reflect off the mirror's surface at an equal angle but in the opposite direction. This is known as the law of reflection. The angle of incidence, which is the angle between the incident ray and the normal to the mirror's surface, will be equal to the angle of reflection, which is the angle between the reflected ray and the normal.
The angle between the normal and the surface of anything is by definition always 90 degrees, regardless of whether it is a mirror, a piece of concrete, a wooden plank, etc.
A mirror has an infinite number of poles due to its smooth and continuous reflective surface. The pole of a mirror is the point where the normal to the mirror surface intersects it, and this point can be anywhere on the mirror surface.
To draw the normal at any point on a spherical mirror, you draw a line perpendicular to the mirror's surface at the point of interest. This normal line represents the direction in which light rays will be reflected off the mirror surface. The normal is crucial for determining the angle of incidence and reflection at that point on the mirror.
A plane mirror is a mirror with a planar reflective surface. For light rays striking a plane mirror, the angle of reflection equals the angle of incidence. The angle of incidence is the angle between the incident ray and the surface normal (an imaginary line perpendicular to the surface). Therefore the angle of reflection is the angle between the reflected ray and the normal and a collimated beam of light does not spread out after reflection from a plane mirror, except for diffraction effects.
The normal (ray).
The angle of incidence is defined as the angle between the incoming light and the line that is normal to the surface at the point where the light 'hits' the surface. The reflectrion angle is the same as the incidence angle. If the angle between the incident ray and the mirror ray is 50, then the angle of incidence is half of this. That is, 25 degrees.
The angle of incidence of mirrors is the angle between the incident ray (incoming light ray) and the normal (perpendicular line) to the surface of the mirror at the point where the ray strikes the mirror.
The angle of reflection is equal to the angle of incidence. It will be at 30o to the surface of the mirror (from the opposite edge) ^ This answer is not correct for SURFACE, but is correct for RELATIVE ^