## Reflection of Waves – Class 11 | Chapter – 15 | Physics Short Notes Series PDF for NEET & JEE

Reflection of Waves: Reflection of waves is a phenomenon in which a wave encounters a boundary or an obstacle and returns back to the medium in which it originated. This phenomenon is commonly observed in sound waves, light waves, and water waves. The angle of incidence, the angle between the incident wave and the normal to the boundary, is equal to the angle of reflection, the angle between the reflected wave and the normal. This principle is known as the law of reflection and applies to all types of waves.

## Types of Reflection of Waves

There are two main types of reflection of waves: specular reflection and diffuse reflection.

• Specular Reflection: This type of reflection occurs when waves encounter a smooth surface, such as a mirror or a calm body of water. In this case, the angle of incidence is equal to the angle of reflection, and the reflected waves maintain their coherence and direction. The reflection is sharp and well-defined, and the surface acts like a perfect mirror.
• Diffuse Reflection: This type of reflection occurs when waves encounter a rough or irregular surface, such as a wall or a turbulent body of water. In this case, the angle of incidence is not equal to the angle of reflection, and the reflected waves scatter in many different directions. The reflection is less sharp and more random, and the surface appears to be matte or non-reflective.

## Applications of Reflection of Waves

Reflection of waves has numerous applications in various fields. Some of the important applications of reflection of waves are:

• Sound wave reflection: In architecture and engineering, the reflection of sound waves is used to design concert halls, auditoriums, and other spaces with optimal acoustics. By controlling the angles and surfaces of reflection, it is possible to enhance or diminish certain frequencies and create a desired sound quality.
• Radar: Reflection of electromagnetic waves is used in radar technology to detect the presence, location, and velocity of objects, such as airplanes, ships, and weather systems. By measuring the time delay and angle of reflection of radio waves, it is possible to generate images of the surroundings and track moving targets.
• Sonar: Reflection of sound waves is used in sonar technology to locate and map underwater objects, such as submarines, ships, and fish. By emitting a pulse of sound waves and analyzing the echoes reflected back, it is possible to determine the distance, shape, and composition of the object.
• Medical imaging: Reflection of ultrasound waves is used in medical imaging to diagnose and treat various conditions, such as pregnancy, heart disease, and cancer. By directing high-frequency sound waves into the body and analyzing the echoes reflected back, it is possible to create images of the internal organs and tissues without the use of radiation.
• Optics: Reflection of light waves is used in various optical devices, such as mirrors, lenses, and telescopes. By controlling the angles and surfaces of reflection, it is possible to manipulate and focus light for a range of applications, such as microscopy, photography, and laser technology.

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