How to Calculate the Internal Resistance of a Cell | JAMB & WAEC Likely Question-In Pidgin скачать в хорошем качестве

How to Calculate the Internal Resistance of a Cell | JAMB & WAEC Likely Question-In Pidgin

Title: How to Calculate the Internal Resistance of a Cell | JAMB & WAEC Likely Question In this tutorial, I will guide you through an important concept in electricity, which is the calculation of the internal resistance of a cell. This type of question is very common in JAMB, WAEC, and NECO exams, so mastering it will help you score high in your physics exams. Given Data Electromotive force (emf) of the cell, E = 1.5 V External resistor, R = 1 Ω Current flowing through the circuit, I = 0.3 A We are asked to find the internal resistance (r) of the cell. Step 1: Use Ohm’s Law and the Total Voltage Equation Ohm’s Law states that: V = IR However, when a cell has internal resistance, the total voltage across the circuit is given by: E = I(R + r) where: E is the emf of the cell I is the current flowing in the circuit R is the external resistance r is the internal resistance of the cell Step 2: Substitute the Given Values 1.5 = 0.3(1 + r) Expand the equation: 1.5 = 0.3 + 0.3r Step 3: Solve for Internal Resistance (r) Subtract 0.3 from both sides: 1.5 - 0.3 = 0.3r 1.2 = 0.3r Divide both sides by 0.3 to isolate r: r = 1.2/0.3 r = 4 Ohms The internal resistance of the cell is 4 Ω. Step 4: Interpretation of the Result Internal resistance is the opposition to current flow within a cell or battery. This resistance causes some of the battery’s energy to be lost as heat, which is why the terminal voltage of a cell is often lower than its emf when a current is flowing. In real-life applications, cells with lower internal resistance are more efficient because they provide more useful power to the external circuit. If the internal resistance is too high, the cell loses a significant amount of energy, reducing its effectiveness. Why This Calculation is Important 1. Common Exam Question – JAMB and WAEC often ask students to calculate the internal resistance of a cell using the total voltage equation. 2. Practical Applications – This concept is useful in designing electrical circuits and choosing batteries with the best efficiency. 3. Foundation for Advanced Topics – Understanding internal resistance helps in studying electrical power, energy dissipation, and even concepts in electronics and engineering. Tips to Remember Always identify given values and check their units before substituting into equations. Ensure proper algebraic manipulation to solve for the unknown variable. Internal resistance affects battery performance, so a lower value is often better in practical applications. Practice more questions to improve your problem-solving speed in exams. Practice Question A battery of emf 12 V is connected in series with a 2 Ω resistor. The current in the circuit is 2.5 A. Calculate the internal resistance of the battery. Drop your answers in the comments section and let’s see how well you understood the concept. If you found this explanation helpful, like and share this video with your friends who are also preparing for JAMB, WAEC, or NECO. If you have any questions or topics you would like me to explain, drop a comment below. Also, subscribe and turn on notifications so you don’t miss any of my future tutorials. #JAMB2025 #WAEC2025 #NECO2025 #PhysicsTutorial #InternalResistance #OhmsLaw #ElectricCircuits #ElectromotiveForce #PhysicsForStudents #JAMBPreparation #WAECPreparation #NECOPreparation #NigeriaStudents #LearnPhysics #pidginenglish