Rapid Revision - Electricity PDF

- RAPID REVISION - Electricity  Rapid Revision First watch One Shot  Electricity Electric charge Electric potential & Resistance Electric power potential diffe...

- RAPID REVISION - Electricity  Rapid Revision First watch One Shot  Electricity Electric charge Electric potential & Resistance Electric power potential difference Electric current Laws related to. electric current N Electric circuit and it's effect Diagram Ohm's law Joule's law of heating Conductors Semiconductors Insulators Allow Current to pass Medium Conductivity Don’t allow Current to pass  physical property of matter that causes it to experience a Electric Charge force when placed in an electromagnetic field. S.I. Unit: Coulomb (C) Positive charge : Loss of electron Negative charge : Gain of electron Properties: 1. Additivity of Charge :Total charge =Nsum of all charges on the body. 2. Charge is Conserved : Charge cannot be created or destroyed. 3. Charge is Invariant : Charge value remains the same, regardless of speed. 4. Quantization of Charge : Charge is a multiple of electron charge: Q = ne. For a material to be a good conductor of electricity, it must have free charge e = 1.6 × 10⁻¹⁹ C. carriers like electrons or ions that can move freely within it.  Electric Current Flow of electric charge through a conductor. Unit: Ampere (A) → 1 A = 1 C/s. I = current, Q = charge, t = time. 1 Ampere: When 1C of charge flows in 1 second then current is said to be 1A. Ammeter: Measures and shows the intensity Nof electric current. Milliammeter: Measures small electric currents. Galvanometer: Detects and measures tiny electric currents. Voltmeter: Measures electric potential difference between two points in a circuit Potential Difference The work done to move a unit positive charge between two points. Unit: Volt (V) → 1 V = 1 J/C. 1 Volt:1 Joule of work done to move 1 unit V = W/Q positive charge between two points. Type of Questions asked? Step 1 : Firstly check what question is asking and write given, to find from question. Out of V,W,Q two quantities will be given and you’ll have to find third one. Also you might need to find out Q from the formulas: I = Q/t or through Q = ne Step 2 : Then use the give formula to find unknowns: V = W/Q *Don’t forget to write units* Electric Circuit A continuous path for current flow, consisting of a power source, conductor, and load. A schematic diagram of an electric circuit comprising – cell, electric bulb, ammeter and plug key  Ohm’s Law Current through a conductor is directly proportional to the potential difference across its ends, at a constant temperature Resistance: Property of a conductor that resists the flow of charges. Unit: Ohm (Ω). Factors Affecting Resistance: Length (l): R∝l Area (A): R∝1/A Material: Different materials have different resistivities (ρ). Type of Questions asked? Step 1 : Firstly check what question is asking and write given, to find from question. Out of V,I,R two quantities will be given and you’ll have to find third one. Other information might also be provided to find other two values. For V; V = W/Q For I; I = Q/t For R; R = ρl/A Questions like what will happen to resistance if we double area or length? Step 2 : Then finally use Ohm’s Law: V = IR *Don’t forget to write units*  Resistance Resistivity Opposition to the flow of electric current in a substance. Resistance of a material with unit length and unit cross-sectional area. Extrinsic property. Intrinsic property. Depends on length and size of the conductor. Independent of length or size of the conductor. Unit: ohm (Ω). Unit: ohm-meter (Ω·m). Electric circuit Series Circuit Parallel Circuit Current remains the same through all resistors. Current divides inversely proportional to resistance. Voltage divides across resistors based on resistance. Voltage remains the same across all resistors. Derivations Electric circuit  Type of Questions asked? Analyze the circuit and see if resistance are in which connection Series Parallel Mixed 1. Calculate reciprocal of each resistance 1. Add individual resistances 1. Simplify circuit by identifying (1/R1, 1/R2,...). (Rt = R1 + R2 +...). series and parallel combinations. 3. Add reciprocals 3. Use Ohm's Law to find total 2. Calculate total resistance for each (1/Rt = 1/R1 + 1/R2 +...). current (I = V/Rt). combination. 4. Take reciprocal of total reciprocal 4. Find voltage across each 3. Use Ohm's Law to find currents resistance (Rt = 1/(1/Rt)). resistor (V = I x R). and voltages. 5. Use Ohm's Law to find total current (I = V/Rt). 6. Find current through each resistor (I = V/R). Ques practice ache se karna!!  Heating effect of electric current Joules Law oh Heating ; Heat is proportional to the square of the current, resistance, and time. For a current I flowing through a resistor of resistance R with a potential difference V, the work done to move a charge Q across the resistor is VQ. The power input to the circuit is: Applications; Electric Bulb: has a tungsten filament inside a neutral gas or vacuum. When current passes through, the filament heats up and emits The energy supplied by the source in time t is VIt. This energy is light, with most energy lost as heat. dissipated as heat in the resistor, so the heat produced is: Electric Fuse: is a low melting point wire in a circuit. If current rises suddenly, the wire melts, breaking the circuit and preventing Using Ohm's law, V=IR, the heat can also be expressed as: damage. Electric Heater: use a nichrome coil with high resistance to generate heat when current flows.  Power (P): Rate of energy consumption.​ Electric Power : Unit: Watt (W) → 1 W = 1 J/s. 1 watt is the power consumed by a device carrying 1A of current at 1V. In practice, a larger unit, the kilowatt (1000 watts), is used. energy used by a circuit to allow current flow. It is the product Electric Energy : of power and time, measured in watt-hours (Wh). Commercial Unit of Energy: One watt-hour is the energy used when 1 watt of power is consumed for 1 hour. The commercial unit of electric energy is the kilowatt-hour (kWh), also called a "unit."  Type of Questions asked? Steps to solve numericals based on heating effect of electric current Step 1: Read the question carefully. Identify the given values (V, I, R) and determine what needs to be found. Out of voltage (V), current (I), and resistance (R), two values will be given, and you'll have to find the third. Other information might be provided to calculate remaining values like power or heat. Step 2: Use Ohm’s Law: V=IR Ensure all units are correct before proceeding. Step 3: For heat produced: or Step 4: For power calculation: Step 5: Substitute the values into the appropriate formulas and calculate the required quantity. Always check your units at the end.