Reflection of Light | Physics for GCSE/IGCSE - Year 11 PDF Download

Ray Diagrams

Angles in Ray Diagrams

• Angles are measured between the direction of the wave (ray) and a line perpendicular (at 90 degrees) to the boundary.
• The angle at which the wave approaches the boundary is known as the angle of incidence (i).
• The angle at which the wave leaves the boundary is known as the angle of reflection (r).

Understanding the Normal

• The line perpendicular (at 90 degrees) to the boundary surface is referred to as the normal.

Ray Diagrams for Light Reflection

• When creating a ray diagram for light reflection, use arrows to indicate the direction of the waves.
• An incident ray is depicted with an arrow pointing towards the boundary.
• A reflected ray is illustrated with an arrow pointing away from the boundary.

Incident and Reflected Rays

• An incident ray always points towards the boundary.
• A reflected ray always points away from the boundary.

Angles of Incidence and Reflection

• The angles of incidence and reflection are commonly denoted as 'i' and 'r', respectively.

The Law of Reflection

• The law of reflection states that the angle of incidence (i) is equal to the angle of reflection (r).

Reflection in a Plane Mirror

• When an object is placed in front of a mirror, an image of that object is visible in the mirror.
• The image in the mirror is the same size as the object and appears at the same distance behind the mirror as the object is in front of it. It's a virtual image.
• The process of image formation can be understood by creating a ray diagram.

Reflection of Light by a Mirror

• When light from an object hits a mirror, it reflects from it (angle of incidence equals angle of reflection).
• To an observer, the reflected ray appears to have originated from the right-hand side of the mirror.
• The reflected ray can be traced back in this direction, forming a virtual ray.

Virtual Ray Formation

• This process can be repeated for another ray traveling in a slightly different direction.
• An image of the object will appear where these two virtual rays intersect.
• The image formed in the mirror is termed a virtual image.
• A virtual image is created by the divergence of rays from the object and cannot be projected onto a surface like paper.