Grade 10
  1. Mechanics  1.1. Dynamics  1.1.1. Motion in one dimension  1.1.2. Motion in two dimensions  1.1.3. Displacement and Distance  1.1.4. Speed and Velocity  1.1.5. Acceleration  1.1.6. Graphical representation of motion  1.1.7. Equations of motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Projectile motion  1.1.10. Relative speed  1.2. Dynamics  1.2.1. Newton's Laws of Motion  1.2.2. Inertia and mass  1.2.3. Force and its types  1.2.4. action and reaction force  1.2.5. Friction and its effects  1.2.6. Coefficient of friction  1.2.7. Circular motion  1.2.8. Centripetal force and centripetal acceleration  1.2.9. Momentum and Impulse  1.2.10. Conservation of momentum  1.2.11. Newton's third law and applications  1.3. Work, Energy and Power  1.3.1. Work done by the force  1.3.2. Work–energy theorem  1.3.3. Kinetic energy  1.3.4. Potential energy  1.3.5. Mechanical energy  1.3.6. Energy Conservation  1.3.7. Power and efficiency  1.3.8. Renewable and non-renewable energy sources  1.4. Gravitational force  1.4.1. Newton's law of universal gravitation  1.4.2. Gravitational field and field strength  1.4.3. Acceleration due to gravity on different planets  1.4.4. Kepler's laws of planetary motion  1.4.5. Orbits and satellites  1.4.6. Weight and apparent weight  1.4.7. Gravitational potential energy
  2. Properties of matter  2.1. States of matter  2.1.1. Solid, liquid and gas  2.1.2. Molecular structure of matter  2.1.3. Intermolecular forces  2.1.4. Plasma and Bose–Einstein condensate  2.2. Pressure  2.2.1. Definition of Pressure  2.2.2. Pressure in liquids  2.2.3. Atmospheric pressure  2.2.4. Pascal's principle  2.2.5. Archimedes' Principle and Buoyancy  2.2.6. Surface tension and capillarity  2.3. Elasticity  2.3.1. Hooke's law  2.3.2. Stress and strain  2.3.3. Elastic Limit and Modulus of Elasticity  2.3.4. Applications of Elasticity
  3. Thermal physics  3.1. heat and temperature  3.1.1. Difference Between Heat and Temperature  3.1.2. Temperature scale  3.1.3. Thermal expansion  3.1.4. Thermal equilibrium  3.2. Heat transfer  3.2.1. Conductivity  3.2.2. Convection  3.2.3. Radiation  3.2.4. Insulation and its applications  3.3. Thermal properties of matter  3.3.1. Specific heat capacity  3.3.2. Latent heat and phase change  3.3.3. Boiling and Melting Point  3.3.4. Heat engines and refrigeration  3.4. Laws of Thermodynamics  3.4.1. Zeroth law of thermodynamics  3.4.2. First law of thermodynamics  3.4.3. Second law of thermodynamics  3.4.4. Carnot cycle
  4. Waves and optics  4.1. Nature and properties of waves  4.1.1. Types of waves in nature and properties of waves  4.1.2. Transverse and longitudinal waves  4.1.3. Wave parameters  4.1.4. Reflection and refraction of waves  4.1.5. Superposition and Interference  4.1.6. Standing Waves and Resonance  4.1.7. Doppler effect  4.2. Sound waves  4.2.1. Characteristics of sound waves  4.2.2. Speed of sound in different mediums  4.2.3. Applications of sound waves  4.2.4. Ultrasound and its uses  4.3. Light Waves and Optics  4.3.1. Nature of light  4.3.2. Reflection of light  4.3.3. Laws of reflection  4.3.4. Mirrors and Image Formation  4.3.5. Refraction of light  4.3.6. Snell's Law  4.3.7. Lenses and Image Formation  4.3.8. Total internal reflection and critical angle  4.3.9. Optical fibre  4.4. Optical Instruments  4.4.1. Microscope  4.4.2. Telescope  4.4.3. Human eye and vision defects  4.4.4. Camera and its working principle
  5. Electricity and Magnetism  5.1. Electrostatics  5.1.1. Electric charge and its properties  5.1.2. Conductors and Insulators  5.1.3. Coulomb's law  5.1.4. Electric field and field lines  5.1.5. Electric potential and potential difference  5.1.6. Capacitors and Capacitance  5.2. Current Electricity  5.2.1. Electric current and its measurement  5.2.2. Ohm's law  5.2.3. Resistance and resistivity  5.2.4. Series and Parallel Circuits  5.2.5. Electric power and energy  5.2.6. Kirchhoff's Laws  5.3. Magnetism and Electromagnetism  5.3.1. Magnetic field and field lines  5.3.2. Magnetic effects of electric current  5.3.3. Electromagnetic induction  5.3.4. Faraday's laws of electromagnetic induction  5.3.5. Transformers and Applications  5.3.6. AC and DC current
  6. Modern Physics  6.1. Nuclear physics  6.1.1. Structure of the atom  6.1.2. Bohr's atomic model  6.1.3. Electron Energy Levels  6.1.4. X-rays and applications  6.2. Radioactivity  6.2.1. Types of radiation  6.2.2. Half-life and radioactive decay  6.2.3. Nuclear reactions and applications  6.2.4. Fission and Fusion  6.3. Quantum physics  6.3.1. Wave–particle duality  6.3.2. Photoelectric effect  6.3.3. Energy quantization  6.3.4. Heisenberg's uncertainty principle
  7. Electronics and Communication  7.1. Semiconductors  7.1.1. Conductors, Insulators and Semiconductors  7.1.2. Diodes and their applications  7.1.3. Transistors and Logic Gates  7.1.4. LEDs and photodiodes  7.2. Communication Systems  7.2.1. Basics of communication  7.2.2. Analog and digital signals  7.2.3. Wireless and optical fibre communication  7.2.4. Radio Waves and Modulation

Grade 10 → Waves and optics → Light Waves and Optics ↓


Mirrors and Image Formation


Mirrors are fascinating objects that have fascinated humans for centuries. They play an important role in the field of optics, which is the study of light and its interaction with matter. Mirrors help us understand how light behaves when it hits different surfaces. In this lesson, we will explore the concepts of mirrors, types of mirrors, and how images are formed using mirrors. We will also discuss some simple physics principles that govern these phenomena.

What is a mirror?

A mirror is a smooth surface that reflects light. Most mirrors used in our daily lives are made of glass with a shiny, metallic coating on the back. This coating reflects the light, allowing us to see our reflection in the mirror. Mirrors can come in different shapes and sizes, and depending on their shape, they have different properties and uses.

Types of mirrors

In basic physics, we mainly study two types of mirrors:

  • Plane mirror
  • Curved mirror

Plane mirror

A plane mirror is a plane mirror that reflects light uniformly. The image formed by a plane mirror appears behind the mirror and is the same size as the object. This image is laterally inverted, which means the left side and the right side are swapped. Plane mirrors follow a straight rule where the angle of incidence is equal to the angle of reflection.

When you stand in front of a plane mirror, you see an image that looks exactly like you, but is inverted horizontally. To understand this, let's say you raise your right hand. In the mirror image, it looks like your left hand is on top. This is called lateral inversion.

Curved mirror

There are mainly two types of curved mirrors, each with different characteristics:

  • Concave mirror
  • Convex mirror

Let us know about these in more detail.

Concave mirror

A concave mirror is a mirror with a surface that is curved inward, like the inside of a bowl. These mirrors can magnify objects and are used in items such as telescopes, makeup mirrors, and headlights.

The important feature of concave mirrors is that they can produce real or virtual images depending on the position of the object relative to the mirror.

Real Image: Formed when light rays actually converge at a point. 
Virtual Image: Formed when light rays appear to diverge from a point.
F (focus) C (Center)

In the figure above, the light rays converge at a point after reflection, forming a real image. Concave mirrors have a focal point (F) and a centre of curvature (C), and these play an important role in determining the type and position of the image formed.

Convex mirror

Convex mirrors have a reflective surface that is curved outward like the back of a spoon. These mirrors are used as rearview mirrors in vehicles because they can provide a wider field of view.

Unlike concave mirrors, convex mirrors always form a virtual image that is smaller than the real object. This image is upright and is located behind the mirror.

F (focus) C (Center)

In this diagram, notice how the reflected rays appear different. The light rays do not actually meet, which is why the image formed is virtual. This wide range of view is why convex mirrors are so useful on vehicles.

Mirror formula and magnification

In mirror calculations, we use a formula and some conventions to obtain information about image formation. The mirror formula is as follows:

1/f = 1/v + 1/u

Here, f is the focal length of the mirror, v is the image distance, and u is the object distance. Using this formula, you can determine any of these three values if you have the other two.

Magnification (m) is another important concept. It tells us how large or small the image is compared to the object. The formula for magnification is:

m = -v / u

Positive magnification represents an upright image, while negative magnification represents an inverted image. Additionally, if the absolute value of the magnification is greater than one, the image is enlarged.

Practical examples and applications

Everyday reflection

Think about how we use mirrors in our daily lives. In the bathroom, plane mirrors allow us to check our appearance, apply makeup, or shave. The images formed in these mirrors are actual size and upright. This illustrates the principle that in plane mirrors the object distance is equal to the image distance, which is why the image appears as it is.

Car mirror

While driving, convex mirrors help you understand your surroundings better, as they provide a wider field of view. Although these mirrors give a smaller image, they provide a complete picture of any car approaching from the side.

Advanced uses in telescopes

Concave mirrors are particularly important in telescopes. These mirrors capture light from distant stars and galaxies, allowing telescopes to form magnified images. The light converges at the focal point, producing sharp images of distant celestial objects.

Conclusion

Mirrors and image formation are not just scientific concepts but an integral part of our daily lives. Understanding how they work helps us appreciate their applications in various fields, from personal grooming to advanced scientific research. The principles of reflection, focal point, and magnification play a vital role in how we view the world around us through mirrors.


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Mirrors and Image Formation

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