Comprehensive Study Notes on Wave Properties and Reflection

Every wave, regardless of its medium or type, exhibits three fundamental behaviors: * Reflection: The bouncing back of a wave when it hits a surface through which it cannot pass. * Refraction: The bending of waves as they enter a new medium at an angle, caused by a change in speed. * Diffraction: The spreading out of waves as they pass through an opening or around the edge of an obstacle.

Specific laws govern the behavior of waves when they undergo reflection, particularly light waves: * First Law: The angle of incidence is equal to the angle of reflection. If the angle of the incoming ray is represented by $i$ and the reflected ray by $r$ , then $i = r$ . * Second Law: The incident ray, the reflected ray, and the normal (an imaginary line perpendicular to the reflecting surface at the point of incidence) all lie within the same geometric plane.

The Process of Seeing: Humans perceive the world because light from a source, such as the Sun or an artificial lamp, strikes an object. This light is then reflected off the object and enters the eye.
Formation of Images in the Eye: The rays of light converge (meet) at the back of the eye on the retina. There, they form a real image.
Real Images: A real image is defined as an image that can be projected onto a screen. This is possible because the light rays physically meet at the location of the image.
Virtual Images: A virtual image is defined as an image that cannot be shown on a screen. This occurs because the light rays do not actually meet; rather, they only appear to be coming from the position of the image when perceived by the observer.

When an object is placed in front of a flat (plane) mirror, the resulting image possesses four distinct properties: * Size Equality: The image is the same size as the original object. * Distance Parity: The image is located exactly as far behind the mirror as the object is placed in front of it. * Geometric Alignment: A line joining any point on the object to its corresponding point on the image will pass through the mirror surface at right angles ( $90^\circ$ ). * Lateral Inversion: The image is laterally inverted, meaning the left and right sides are reversed relative to the object.

Aim: To verify the laws of reflection and precisely determine the position of a virtual image.
Apparatus: Plane mirror, pins (object pin and search pin), ruler, paper.
Finding the Position using No Parallax: * To find the exact location of a virtual image of a pin in a mirror, a second pin (the search pin) is placed behind the mirror. * The search pin is adjusted until it perfectly aligns with the virtual image seen inside the mirror. * No Parallax Condition: The search pin is in the correct location when it remains aligned with the virtual image even as the observer moves their head from side to side. This state is called "no parallax" or the absence of relative movement between the search pin and the image. This confirms that the search pin is at the exact physical position where the virtual image appears to be.