- When light strikes the boundary between two transparent media, it undergoes partial reflection and partial refraction.
- A ray passing from a rarer to a denser medium bends towards the normal, while one passing from a denser to a rarer medium bends away from the normal.
- The angles of incidence and refraction are generally unequal, causing light to bend.
- A ray incident normally (i = 0°) passes undeviated, even though its speed changes.
- Refraction occurs due to a change in the speed of light when it passes from one medium to another.
Topics
Electric Charges and Fields
- Electric Charge
- Electrical Conduction in Solids
- Principle of Superposition
- Electric Field
- Electric Field Due to a System of Charges
- Physical Significance of Electric Field
- Electric Lines of Force
- Electric Flux
- Electric Dipole
- Dipole in a Uniform External Field
- Continuous Charge Distribution
- Gauss’s Law
- Applications of Gauss' Theorem
- Charging by Induction
- Electric Field Intensity Due to a Point-Charge
- Uniformly Charged Infinite Plane Sheet and Uniformly Charged Thin Spherical Shell (Field Inside and Outside)
- Overview: Gauss' Theorem
- Conductors and Insulators
- Important Properties of Electric Charge
- Scalar Form of Coulomb’s Law
- Electric Field due to an Electric Dipole
Electrostatics
Current Electricity
Electrostatic Potential and Capacitance
- Electric Potential
- Potential Due to a Point Charge
- Potential Due to an Electric Dipole
- Potential Due to a System of Charges
- Equipotential Surfaces
- Relation Between Electric Field and Electrostatic Potential
- Potential Energy of a System of Charges
- Potential Energy of a Single Charge
- Potential Energy of a System of Two Charges in an External Field
- Potential Energy of a Dipole in an External Field
- Electrostatics of Conductors
- Dielectrics
- Capacitors and Capacitance
- The Parallel Plate Capacitor
- Effect of Dielectric on Capacity
- Combination of Capacitors
- Energy Stored in a Charged Capacitor
- Van De Graaff Generator
- Capacitance of a Parallel Plate Capacitor with and Without Dielectric Medium Between the Plates
- Free Charges and Bound Charges Inside a Conductor
- Conductors and Insulators Related to Electric Field
- Electrical Potential Energy of a System of Two Point Charges and of Electric Dipole in an Electrostatic Field
- Potential and Potential Difference
- Overview: Electric Potential
- Overview: Capacitors and Dielectrics
Magnetic Effects of Current and Magnetism
Current Electricity
- Electric Current
- Concept of Electric Currents in Conductors
- Ohm's Law
- Current Density
- Drift of Electrons and the Origin of Resistivity
- Limitations of Ohm’s Law
- Resistivity of Various Materials
- Temperature Dependence of Resistance
- Electrical Power
- Cells, Emf, Internal Resistance
- Cells in Series
- Kirchhoff’s Laws
- Wheatstone Bridge
- Conductivity and Conductance;
- Delta Star Transformation
- Potential Difference and Emf of a Cell
- Measurement of Internal Resistance of a Cell
- Potentiometer
- Metre Bridge: Slide-Wire Bridge
- A combination of resistors in both series and parallel
- Specific Resistance
- V-I Characteristics (Linear and Non-linear)
- Flow of Electric Charges in a Metallic Conductor
- Overview: Electric Resistance and Ohm's Law
- Overview: DC Circuits and Measurements
Electromagnetic Induction and Alternating Currents
Moving Charges and Magnetism
- Magnetic force
- Sources and Fields of Magnetic Force
- Magnetic Field, Lorentz Force
- Force on a Current Carrying Conductor in a Magnetic Field
- Motion in a Magnetic Field
- Biot-Savart Law
- Magnetic Field on the Axis of a Circular Current Loop
- Ampere’s Circuital Law
- Solenoid and the Toroid - the Solenoid
- Force Between Two Parallel Currents, the Ampere
- Circular Current Loop as a Magnetic Dipole
- Torque on a Rectangular Current Loop in a Uniform Magnetic Field
- Moving Coil Galvanometer
- Oersted's Experiment
- Solenoid and the Toroid - the Toroid
- Magnetic Diapole
- Torque on a Current-Loop in a Uniform Magnetic Field
- Force on a Current - Carrying Conductor in a Uniform Magnetic Field
- Force on a Moving Charge in Uniform Magnetic and Electric Fields
- Straight and Toroidal Solenoids (Only Qualitative Treatment)
- The Magnetic Dipole Moment of a Revolving Electron
- Velocity Selector
- Cyclotron
- Overview: Moving Charges and Magnetic Field
- Overview: Torque on a Current-Loop : Moving-Coil Galvanometer
Electromagnetic Waves
Magnetism and Matter
- Concept of Magnetism
- The Bar Magnet
- Magnetism and Gauss’s Law
- Magnetisation and Magnetic Intensity
- Magnetic Properties of Materials
- Permanent Magnet
- Curie Law of Magnetism
- Hysteresis: Retentivity and Coercivity
- The Earth’s Magnetism
- Torque on a Magnetic Dipole (Bar Magnet) in a Uniform Magnetic Field
- Dipole in a Uniform External Field
- Magnetic Field Intensity Due to a Magnetic Dipole (Bar Magnet) Perpendicular to Its Axis
- Magnetic Field due to a Bar Magnet
- Magnetic Dipole Moment of a Revolving Electron
- Current Loop as a Magnetic Dipole: Magnetic Dipole Moment of Current Loop
- Magnetic Substances
- Overview: Magnetism and Mater
Optics
Electromagnetic Induction
- Electromagnetic Induction
- The Experiments of Faraday and Henry
- Magnetic Flux
- Faraday's Laws of Electromagnetic Induction
- Lenz’s Law and Conservation of Energy
- Motional Electromotive Force (e.m.f.)
- Mutual Inductance
- Self Inductance
- A.C. Generator
- Energy Consideration: a Quantitative Study
- Eddy Currents or Foucault Currents
- Induced Current and Induced Charge
- Overview - Electromagnetic Induction
Dual Nature of Radiation and Matter
Alternating Current
- Alternating current (AC) and Direct Current (DC)
- Different Types of AC Circuits: AC Voltage Applied to a Resistor
- Representation of AC Current and Voltage by Rotating Vectors - Phasors
- Different Types of AC Circuits: AC Voltage Applied to an Inductor
- Different Types of AC Circuits: AC Voltage Applied to a Capacitor
- Different Types of AC Circuits: AC Voltage Applied to a Series LCR Circuit
- Power in AC Circuit
- Forced Oscillations and Resonance
- Transformers
- LC Oscillations
- Reactance and Impedance
- Peak and Rms Value of Alternating Current Or Voltage
- Overview: AC Circuits
Atoms and Nuclei
Electromagnetic Waves
- Elementary Facts About Electromagnetic Wave Uses
- Electromagnetic Spectrum
- Transverse Nature of Electromagnetic Waves
- EM Wave
- Displacement Current
- Overview of Electromagnetic Waves
Ray Optics and Optical Instruments
- Reflection of Light by Spherical Mirrors
- Refraction of Light
- Refraction at a Spherical Surface and Lenses
- Refraction by a Lens
- Refraction at Spherical Surfaces
- Power of a Lens
- Refraction of Light Through a Prism
- Optical Instruments
- Simple Microscope or a Reading Glass
- Compound Microscope
- Telescope
- Optical Instruments: the Eye
- Laws of Refraction
- Spherical Mirror > Concave Mirror
- Rarer and Denser Medium
- Lens Maker's Formula
- Thin Lens Formula
- Concept of Lenses
- Some Natural Phenomena Due to Sunlight
- Dispersion by a Prism
- Magnification
- Total Internal Reflection
- Ray Optics - Mirror Formula
- Overview of Ray Optics and Optical Instruments
- Light Process and Photometry
Electronic Devices
Wave Optics
- Introduction of Wave Optics
- Huygens' Principle
- Refraction of a Plane Wave
- Refraction at a Rarer Medium
- Reflection of a Plane Wave by a Plane Surface
- Coherent and Incoherent Addition of Waves
- Interference of Light Waves and Young’s Experiment
- Diffraction of Light
- The Single Slit
- Seeing the Single Slit Diffraction Pattern
- Refraction of Monochromatic Light
- Polarisation
- Law of Malus
- Principle of Superposition of Waves
- Corpuscular Theory
- Plane Polarised Light
- The Validity of Ray Optics
- Doppler Effect
- Width of Central Maximum
- Resolving Power of Microscope and Astronomical Telescope
- Interference
- Proof of Laws of Reflection and Refraction Using Huygens' Principle
- Brewster's Law
- Fraunhofer Diffraction Due to a Single Slit
- Coherent and Incoherent Sources and Sustained Interference of Light
- Speed of Light
- Reflection and Refraction of Plane Wave at a Plane Surface Using Wave Fronts
- Overview: Wave Optics
Communication Systems
Dual Nature of Radiation and Matter
- Dual Nature of Radiation
- Electron Emission
- Photoelectric Effect - Hertz’s Observations
- Photoelectric Effect - Hallwachs’ and Lenard’s Observations
- Experimental Study of Photoelectric Effect
- Photoelectric Effect and Wave Theory of Light
- Einstein’s Photoelectric Equation: Energy Quantum of Radiation
- Particle Nature of Light: The Photon
- Einstein’s Equation - Particle Nature of Light
- Davisson and Germer Experiment
- de-Broglie Relation
- Wave Nature of Matter
- Overview: Dual Nature of Radiation and Matter
The Special Theory of Relativity
Atoms
- Introduction of Atoms
- Alpha-particle Scattering and Rutherford’s Nuclear Model of Atom
- Atomic Spectra
- Bohr’s Model for Hydrogen Atom
- Energy Levels
- The Line Spectra of the Hydrogen Atom
- De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation
- Heisenberg and De Broglie Hypothesis
- Thompson Model
- Dalton's Atomic Theory
- Hydrogen Spectrum
- Overview: Atoms
Nuclei
- Atomic Masses and Composition of Nucleus
- Size of the Nucleus
- Mass - Energy
- Nuclear Binding Energy
- Nuclear Force
- Alpha Decay
- Beta Decay
- Gamma Decay
- Controlled Thermonuclear Fusion
- Nuclear Reactor
- Mass Defect and Binding Energy
- Atomic Mass, Mass - Energy Relation and Mass Defect
- Overview: Nuclei
- Law of Radioactive Decay
Semiconductor Electronics - Materials, Devices and Simple Circuits
- Concept of Semiconductor Electronics: Materials, Devices and Simple Circuits
- Classification of Metals, Conductors and Semiconductors
- Energy Bands in Conductors, Semiconductors and Insulators
- Intrinsic Semiconductor
- Extrinsic Semiconductor
- p-n Junction
- Semiconductor Diode
- Application of Junction Diode as a Rectifier
- Integrated Circuits
- Feedback Amplifier and Transistor Oscillator
- Transistor as a Device
- Basic Transistor Circuit Configurations and Transistor Characteristics
- Transistor Action
- Transistor: Structure and Action
- Digital Electronics and Logic Gates
- Transistor as an Amplifier (Ce-configuration)
- Transistor and Characteristics of a Transistor
- Zener Diode as a Voltage Regulator
- Special Purpose P-n Junction Diodes
- Diode as a Rectifier
- Triode
- Overview: Semiconductor Electronics
Communication Systems
- Detection of Amplitude Modulated Wave
- Production of Amplitude Modulated Wave
- Basic Terminology Used in Electronic Communication Systems
- Sinusoidal Waves
- Modulation and Its Necessity
- Amplitude Modulation (AM)
- Need for Modulation and Demodulation
- Satellite Communication
- Propagation of EM Waves
- Bandwidth of Transmission Medium
- Bandwidth of Signals
The Special Theory of Relativity
- The Special Theory of Relativity
- The Principle of Relativity
- Maxwell'S Laws
- Kinematical Consequences
- Dynamics at Large Velocity
- Energy and Momentum
- The Ultimate Speed
- Twin Paradox
- Definition: Refraction
- Definition: Refracted Light
- Definition: Refraction of Light
- Key Points: Refraction of Light
Maharashtra State Board: Class 10
Introduction
Refraction is the bending of light when it passes from one medium to another due to a change in speed. This happens because different substances have different densities, which affect how light travels through them.
"Refraction is the change in the direction of a wave as it passes from one medium to another due to a change in its speed."
Causes of Refraction:
- Light changes speed when moving between materials of different densities.
- If light enters a denser medium (e.g., air to water), it slows down and bends towards the normal.
- If light enters a less dense medium, it speeds up and bends away from the normal.
- If light enters perpendicularly, it does not bend but still changes speed.
Maharashtra State Board: Class 10
Activity 1
Pencil in Water (Observing Refraction):
- Take a transparent glass and fill it with water.
- Dip a pencil vertically into the water and observe its thickness.
- Tilt the pencil at an angle and observe again.
- In both cases, the portion of the pencil inside the water appears thicker than the portion above.
- When the pencil is tilted, it looks bent or broken at the water's surface.
This effect occurs because light changes direction (refracts) when it moves from water to air. The bending of light makes the pencil appear distorted, demonstrating the refraction of light.
Maharashtra State Board: Class 10
Activity 2
Disappearing and Reappearing Coin
- Place a 5-rupee coin in a metallic vessel.
- Slowly move away until the coin disappears from view.
- Ask a friend to pour water into the vessel while you keep looking in the same direction.
- As the water level rises, the coin becomes visible again.
Light rays coming from the coin bend when passing from water to air, changing their path. This makes the coin, which was earlier invisible, appear again due to the refraction of light.
Maharashtra State Board: Class 10
Activity 3
Refraction of Light Through a Glass Slab:
- Place a glass slab on a paper and draw its outline (PQRS).
- Draw an inclined ray (AN) on side PQ, marking point N where it meets the slab.
- Fix two pins (A and B) along the ray and look from the other side.
- Align two more pins (C and D) with the images of A and B.
- Remove the slab and draw a line through C and D, meeting SR at point M.
- Join M and N to trace the path of the refracted ray.
Refraction of light passing through a glass slab
Observation and Explanation:
1. The incident ray (AN) strikes the glass at point N and bends due to refraction.
2. The first refraction occurs when light moves from air to glass at N, bending toward the normal.
3. The second refraction occurs when light moves from glass to air at M, bending away from the normal.
The angles of refraction are measured as:
- i = angle of incidence (AN to normal at N).
- r = angle of refraction at N.
- i₁ = r, meaning the refraction inside the glass follows the same pattern.
- e = emergent angle, which equals i due to the opposite bending effect.
The emergent ray (MD) is parallel to the incident ray (AN) but is slightly displaced from it due to the shift caused by the refraction process.
This activity shows that light bends when passing between different transparent media, following the laws of refraction. The incident and emergent rays remain parallel but are slightly displaced, demonstrating the refraction through a rectangular glass slab.
CISCE: Class 10
Definition: Refraction
The change in the direction of the path of light when it passes from one transparent medium to another transparent medium is called refraction. The refraction of light is essentially a surface phenomenon.
CISCE: Class 10
Definition: Refracted Light
Refracted light is the part of light enters into the other medium and travels in a straight path but in a direction different from its initial direction and is called the refracted light.
CBSE: Class 10
Maharashtra State Board: Class 10
CISCE: Class 12
Maharashtra State Board: Class 10
CISCE: Class 12
Definition: Refraction of Light
When travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes. This phenomenon is known as refraction of light.
OR
Light changes its direction when going from one transparent medium to another transparent medium. This is called the refraction of light.
OR
The bending of the light ray from its path in passing from one medium to the other medium is called 'refraction' of light.
CISCE: Class 10
