Topics
Force, Work, Power and Energy
Force
Light
Work, Energy and Power
- Concept of Work
- Measurement of Work
- Expression for Work (W = F S cosθ)
- Work Done by the Force of Gravity (W = mgh)
- Concept of Power
- Work vs Power
- Concept of Energy
- Energy vs Power
- Mechanical Energy > Potential Energy (U)
- Mechanical Energy > Kinetic Energy (K)
- Potential vs Kinetic Energy
- Conversion of Potential Energy into Kinetic Energy
- Forms of Energy > Solar Energy
- Forms of Energy > Heat Energy
- Forms of Energy > Light Energy
- Forms of Energy > Chemical Energy
- Forms of Energy > Hydro Energy
- Forms of Energy > Electrical Energy
- Forms of Energy > Nuclear Energy
- Forms of Energy > Geo Thermal Energy
- Forms of Energy > Wind Energy
- Forms of Energy > Sound Energy
- Forms of Energy > Magnetic Energy
- Forms of Energy > Mechanical Energy
- Conversion of Energies
- Principle of Conservation of Energy
- Proof: Kinetic + Potential Energy = Constant for Free Fall
- Application of the Principle of Conservation of Energy
Sound
Machines
- Concept of Machines
- Technical Terms Related to a Machine
- Principle of a Machine
- Efficiency, Mechanical Advantage, and Velocity Ratio
- Levers
- Types of Levers
- Pulley
- Single Fixed Pulley
- A Single Movable Pulley
- Single Pulley vs Single Movable Pulley
- Combination of Pulleys
- Using one fixed pulley and other movable pulleys
- Using several pulleys in two blocks (block and tackle system)
Electricity and Magnetism
Refraction of Light at Plane Surfaces
- Light: Reflection and Refraction
- Refraction of Light
- Laws of Refraction
- Speed of Light in Different Media
- Principle of Reversibility of the Path of Light
- Refraction Laws & Glass Index
- Refraction of Light Through a Rectangular Glass Block
- Multiple Images in a Thick Mirror
- Prism
- Refraction of Light Through a Prism
- Real and Apparent Depth
- Apparent Bending of a Stick Under Water
- Consequences of Refraction of Light
- Transmission of Light From a Denser Medium to a Rarer Medium
- Critical Angle
- Relationship between Critical Angle and Refractive Index
- Total Internal Reflection
- Total Internal Reflection in a Prism
- Total Internal Reflection Through a Right-Angled Isosceles Prism
- Total Internal Reflection Through an Equilateral Prism
- Total Internal Reflection Through Right-angled prism
- Use of a Total Internal Reflecting Prism in Place of a Plane Mirror
- Total Internal Reflection vs Reflecting from a Plane Mirror
- Consequences of Total Internal Refraction
Heat
Refraction Through a Lens
- Concept of Lenses
- Action of a Lens as a Set of Prisms
- Technical Terms Related to a Lens
- Convex Lens vs Concave Lens
- Refraction of Light Through an Equi-Convex Lens and an Equi-Concave Lens
- Principal Rays for Ray Diagrams
- Real Image vs Virtual Image
- Construction of a Ray Diagram for a Lens
- Images Formed by Convex Lenses
- Images Formed by Concave Lenses
- Sign Convention
- Lens Formula
- Linear Magnification
- Power of a Lens
- Magnifying Glass Or Simple Microscope
- Application of Lenses
- Experimental Determination of Focal Length of Convex Lens
- Convex Lens vs Concave Lens
Modern Physics
Spectrum
- Deviation Produced by a Triangular Prism
- Colour in White Light with Their Wavelength and Frequency Range
- Dispersion of Light
- Electromagnetic Spectrum
- Properties and Uses of Different Radiations of the Electromagnetic Spectrum
- Distinction between Ultraviolet, Visible, and Infrared Radiations
- Scattering of Light
- Applications of Scattering of Light
Sound
- Sound Waves
- Light Waves vs Sound Waves
- Reflection of Sound Waves
- Echo
- Determination of Speed of Sound by the Method of Echo
- Use of Echoes
- Natural Vibrations
- Damped Vibrations
- Natural Vibrations vs Damped Vibrations
- Forced Vibrations
- Natural Vibrations vs Forced Vibrations
- Resonance (a special case of forced vibrations)
- Demonstration of Resonance
- Forced Vibrations vs Resonant Vibrations
- Examples of Resonance
- Characteristics of Sound
- Loudness and Intensity
- Pitch and frequency
- Quality and Wave Form
- Music and Noise
Current Electricity
- Electric Charge
- Electric Current
- Potential and Potential Difference
- Electric Resistance
- Ohm's Law
- Experimental Verification of Ohm’s Law
- Ohmic and Non-ohmic Resistors
- Specific Resistance
- Choice of Material of a Wire
- Superconductors
- Electro-Motive Force of a Cell
- Terminal Voltage of a Cell
- Internal Resistance of a Cell
- Resistance of a System of Resistors
- Resistors in Series
- Resistors in Parallel
- A combination of resistors in both series and parallel
- Forms of Energy > Electrical Energy
- Measurement of Electrical Energy
- Electrical Power
- Commercial Unit of Electrical Energy
- Power Rating of Common Electrical Appliances
- Household Consumption of Electric Energy
- Heating Effect of Electric Current
Household Circuits
- Transmission of Power from the Power Generating Station to the Consumer
- Power Distribution to a House
- House Wiring (Ring System)
- Fuse
- Reason for connecting the fuse in the live wire
- Current Rating of a Fuse
- Switches
- Circuits with Dual Control Switches (Staircase Wire)
- Earthing
- Three-pin Plug and Socket
- Colour Coding of Wires in a Cable
- High Tension Wires
- Precautions to Be Taken While Using Electricity
Electro-Magnetism
- Oersted's Experiment
- Applications of Biot-Savart's Law > Magnetic Field due to a Finite Straight Current-Carrying Wire
- Right-hand Thumb Rule
- Applications of Biot-Savart's Law > Magnetic Field at the Centre of a Circular Loop
- Applications of Ampere’s Circuital Law > Magnetic Field of a Long Straight Solenoid
- Electromagnet
- Permanent Magnet
- Comparison of an Electro Magnet with a Permanent Magnet
- Advantages of an Electromagnet over a Permanent Magnet
- Uses of Electromagnet
- Force on a Current Carrying Conductor in a Magnetic Field
- Simple D.C. Motor
- Electromagnetic Induction
- Demonstration of the Phenomenon of Electromagnetic Induction
- Faraday's Explanation
- Faraday's Laws of Electromagnetic Induction
- A.C. Generator
- Frequency of an a.c. in Household Supplies
- Comparison Between A.C. Generator and D.C. Motor
- Transformers
Calorimetry
- Heat
- The Temperature and a Thermometer
- Factors Affecting the Quantity of Heat Absorbed to Increase the Temperature of a Body
- Heat vs Temperature
- Thermal or Heat Capacity
- Specific Heat Capacity
- Heat Capacity vs Specific Heat Capacity
- Specific Heat Capacity of Some Common Substances
- Calorimetry
- Principle of Method of Mixtures or Principle of Calorimetry
- Natural Phenomena and Consequences of High Specific Heat Capacity of Water
- Examples of High and Low Heat Capacity
- Change of State
- Melting and Freezing
- Melting Point and Its Effects
- Vaporisation or Boiling
- Boiling Point and Its Effects
- Latent Heat
- Specific Latent Heat of Fusion of Ice
- Explanation of Latent Heat of Melting based on Kinetic Model
- Natural Consequences of High Specific Latent Heat of Fusion of Ice
Radioactivity
- Structure of the Atom and Nucleus
- Atomic Model
- Isotopes
- Isobars
- Isotones
- Radioactivity
- Radioactivity as emission of Alpha, Beta, and Gamma Radiations
- Properties of Alpha Particles
- Properties of Beta Particles
- Properties of Gamma Radiations
- Distinction between the Properties of α, β, and γ Radiations
- Changes Within the Nucleus in Alpha, Beta and Gamma Emission
- Uses of Radioactive Isotopes
- Sources of Harmful Radiations
- Harmful Effects of Radiation
- Safety Precautions While Using Nuclear Energy
- Background Radiations
- Forms of Energy > Nuclear Energy
- Nuclear Fission
- Radioactive Decay Vs Nuclear Fission
- Nuclear Fusion
- Nuclear Fission Vs Nuclear Fusion
- Definition: Loudness
- Key Points: Loudness and Intensity
Maharashtra State Board: Class 7
Intensity of Sound and Sound Level:
The intensity and sound level tell us how loud or soft a sound is. Sound level refers to the intensity of sound as perceived by our ears.
- The intensity of sound depends on the square of the amplitude of the vibration.
- If the amplitude is doubled, the intensity becomes 4 times greater (since 22 = 4). This shows that even small changes in amplitude can cause large changes in intensity.
- The decibel (dB) is the unit used to measure sound level.
- It is named after Alexander Graham Bell, the inventor of the telephone, in recognition of his work on sound.
- When the intensity of sound increases by 10 times, the sound level rises by 10 dB.
This means a small increase in sound intensity can make a noticeable increase in the sound level we hear.
Decibel levels of some common sounds:
- Beginning of audible sound: 0 dB
- Normal breathing: 10 dB
- Murmuring from 5 metres away: 30 dB
- Normal conversation (between two persons): 60 dB
- Heavy traffic: 70 dB
- Ordinary factories – 80 dB
- Jet engine: 130 dB
- Start of ear-splitting sound: 120 dB
Hearing is temporarily affected by sounds of frequency greater than 1000 Hz and levels higher than 100 dB. This can result in temporary deafness. Workers who work near aeroplane engines experience this.
CISCE: Class 10
Definition: Loudness
Loudness is the characteristic by virtue of which a loud sound can be distinguished from a faint one, both having the same pitch and quality.
CISCE: Class 10
key Points: Loudness and Intensity
- Loudness of sound depends on the amplitude of the wave, and a loud sound corresponds to a wave of large amplitude.
- Intensity of a sound wave is the amount of sound energy passing per second, usually through a unit area, and its unit is watts per square metre² (W m⁻²).
- Loudness is subjective because it depends on the listener's ear sensitivity, whereas intensity is objective.
- Loudness depends on the square of the amplitude, the distance from the source, the surface area of the vibrating body, the density of the medium, and the presence of resonant bodies.
- Sound level is expressed in decibels (dB), and noise pollution is caused by undesirable loud and harsh sounds at levels above 120 dB.
