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 → Electricity and Magnetism → Current Electricity ↓


Ohm's law


Ohm's law is a fundamental principle in the study of electricity that shows the relationship between voltage, current, and resistance. Understanding this law is essential for anyone interested in electrical circuits. In simple terms, Ohm's law states that in an ideal conductor, the current flowing through it is directly proportional to the voltage across it, provided physical conditions such as temperature remain constant.

What is Ohm's law?

Ohm's law can be expressed by this formula:

V = I * R

Where:

  • V stands for voltage, measured in volts (V).
  • I is the current, measured in amperes (A).
  • R is the resistance, measured in ohms (Ω).

This formula shows how voltage, current, and resistance are interconnected. If you know any two of these values, you can calculate the third. This makes Ohm's law a powerful tool for analyzing electrical circuits.

Understanding the concepts

Voltage

Voltage is the electrical potential difference between two points. It's what pushes electrical charges through a circuit. You can think of it like water pressure in a pipe; higher pressure means more water flows. Similarly, higher voltage means more electric current can flow through a circuit.

Low potential (0V) High Capacity(5V) Voltage

Current

Current is the flow of electrical charge. It's like the flow of water in a pipe. More current means more electricity is flowing. Higher voltage causes higher current, just like higher water pressure causes more water to flow.

current

Resistance

Resistance is a measure of how difficult it is for current to flow through a material. High resistance makes it difficult for current to flow, similar to narrow pipes that prevent water flow. Resistance depends on factors such as the type of material, length, and cross-sectional area.

resistance

Relation between voltage, current and resistance

According to Ohm's law, the current flowing through a conductor between two points is proportional to the voltage between those two points and inversely proportional to the resistance between them.

This can be seen as follows:

Voltage (V) Current(I) Resistance(R)

How Ohm's Law Works in Simple Circuits

Let's consider a simple circuit consisting of a battery and a resistor. The battery provides the voltage, and the resistor provides the resistance. Ohm's law applies as follows:

V = I * R

Suppose the battery provides a voltage of 9V, and the resistance of the resistor is 3Ω. To find the current flowing through the circuit, rearrange the formula:

I = V / R

Substituting the known values:

I = 9V / 3Ω

The current I is 3A. Therefore, 3 amperes of current flows in the circuit.

Example: Calculate the voltage.

If the current in a circuit is 4A and resistance is 2Ω, then what is the voltage?

V = I * R = 4A * 2Ω = 8V

The voltage is 8 volts.

Practical applications of Ohm's law

Ohm's law is widely used in a variety of applications, from simple projects to complex electronic systems. Understanding this law is important for designing and analyzing electrical and electronic circuitry. Here are some common applications:

  • Designing electronic circuits: Engineers use Ohm's law to calculate the resistance needed to achieve a desired current in a circuit.
  • Electrical power calculation: Knowing two of the current, voltage and resistance, the power in electrical devices can be calculated using the formula: P = V * I
  • Safety measures: Electricians determine appropriate wiring and materials to prevent overheating or short circuits, keeping the installation safe.

Through a variety of exercises and real-world examples, students can deepen their understanding of Ohm's Law:

Example: Calculate the resistance.

If the voltage in a circuit is 12V and current is 6A, then what is the resistance?

R = V / I = 12V / 6A = 2Ω

The resistance is 2 ohms.

In short, Ohm's Law is not just a theoretical concept; it is a practical tool that bridges the gap between theoretical physics and real-world applications. Its simplicity and adaptability make it foundational in physics and engineering, embodying the beauty and practicality of scientific laws.

Limitations of Ohm's law

Ohm's law is fundamental, but it is not universal. It is important to know its limitations:

  • Non-linear devices: Ohm's law applies mainly to ohmic materials, where current and voltage have a linear relationship. Devices such as diodes do not strictly follow Ohm's law.
  • Temperature dependence: In practice, temperature affects resistance, which affects current flow. Ohm's law assumes that temperature and other physical properties are constant.
  • Frequency dependence: In AC circuits, resistance is often replaced by impedance, which considers both resistance and reactance, which are factors not covered by Ohm's law.

Understanding these limitations is as important as understanding the law, especially when exploring advanced topics in electronics and electrical engineering.

Ohm's law plays an important role in fundamental physics education, providing clear and concise ways to understand complex circuit systems. It provides a stepping stone for further exploration in fields such as electronics, electrical engineering, and applied physics. By building on the concepts presented by Ohm's law, students can understand more complex ideas in electricity and magnetism.

In conclusion, Ohm's Law is much more than an equation; it is a gateway to understanding the fascinating field of electricity. Through examples, applications, and visualizations, its principles are unveiled, providing insight into the behavior of electrical circuits and contributing to the ever-evolving field of technology.


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Ohm's law

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