Electric Current and Circuits - Grade 10 Physics PDF
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This document covers electric current, circuits, and energy transformations, including calculations for electric power and resistance. The material aligns with a Grade 10 physics curriculum, featuring diagrams, circuit symbols and questions to enhance understanding of electrical concepts.
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Grade 10 Advanced PHYSICS Chapter 4: ELECTRIC CURRENT AND CIRCUITS Lesson 1: Current and Circuits Electric current: Symbol – I Unit – ampere (A) In an electric circuit electrons flow from negative terminal to positive terminal of the...
Grade 10 Advanced PHYSICS Chapter 4: ELECTRIC CURRENT AND CIRCUITS Lesson 1: Current and Circuits Electric current: Symbol – I Unit – ampere (A) In an electric circuit electrons flow from negative terminal to positive terminal of the battery. The direction of conventional current is from positive terminal (high electric potential) to negative terminal (low electric potential) of the battery Energy transformation P a g e 1 | 11 Conservation of charge and energy in an electric circuit Conservation of charge in an electric circuit In an electric circuit, the amount of charge flowing through each component is the same. Example: If 1 coulomb of charge flows through battery in 1 second, the same 1 coulomb flows through the bulb in 1 second. Charge is a conserved quantity throughout the circuit. Conservation of Energy in an Electric Circuit Energy is conserved in an electric circuit. The change in electrical energy (ΔE) is given by: ΔE = q ΔV The net change in potential energy of charges completing a full loop in the circuit is zero. A charge gains electrical potential energy when it passes through a battery and then loses this energy to the various components as it travels through the circuit. Example If the potential difference (ΔV) between two wires is 12 V: o The battery does 120 J of work on each coulomb of charge. o Each coulomb of charge delivers 120 J of energy to the bulb. Draw a diagram of an electric circuit and explain how energy is conserved in it. ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… P a g e 2 | 11 The rate of flow of electric charge is called electric current. 𝒄𝒉𝒂𝒓𝒈𝒆 𝒆𝒍𝒆𝒄𝒕𝒓𝒊𝒄 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 = 𝒕𝒊𝒎𝒆 𝒒 𝑰= 𝒕 When 1 coulomb charge passes through a wire in 1 second the current through it is 1 ampere. Electric circuit and circuit diagram Any closed loop or conducting path allowing electric charges to flow is called an electric circuit. Circuit diagram. Electric current flow from positive terminal of cell to its negative terminal Ammeter is a device to measure electric current in a circuit. Ammeter is connected in series in a circuit, and it has very low resistance as current has to pass through it easily. Voltmeter is a device used to measure potential difference across any electric component. Voltmeter is connected in parallel across an electric component. Voltmeter has very high resistance as no current should pass through it. P a g e 3 | 11 Ammeter: …………………………………………………………………………. Voltmeter: ………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… P a g e 4 | 11 ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… Electric power Symbol – P Unit – watt (W) Power is the rate at which electrical energy is transformed. ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… P a g e 5 | 11 ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… P a g e 6 | 11 Ohm’s law and Resistance Ohm's law states that current through a wire is directly proportional to potential difference between its ends. Resistance Symbol – R Unit – ohm (Ω) Resistance is a measure of the opposition to current flow in an electrical circuit. One ohm is defined as that resistance of an object when a current of 1 ampere flows through an object having a potential difference of 1 Volt. What are the factors on which resistance of a conductor depend on? P a g e 7 | 11 Ohmic and non-Ohmic conductors Conductors which obey Ohm’s law are called Ohmic conductors. Ohmic conductors will have constant resistance independent of potential difference applied across it. Examples: metallic conductors Conductors which do not obey Ohm’s law are called non-ohmic conductors. Resistance of non-ohmic conductors change depending on potential difference applied across it. Resistor A resistor is a device designed to have a specific resistance. Resistors may be made of carbon, semiconductors, or wires that are long and thin. ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… Variable resistors Variable Resistors are used to control the current in circuits or parts of circuits. Some variable resistors consist of a coil of resistance wire and a sliding contact point. Moving the contact point to various positions along the coil varies the amount of wire in the circuit. As more wire is placed in the circuit, the resistance of the circuit increases; thus, the current changes in accordance P a g e 8 | 11 with the equation I = ΔV / R. In this way, the speed of a motor can be adjusted from fast, with little wire in the circuit, to slow, with a lot of wire in the circuit. P a g e 9 | 11 P a g e 10 | 11 P a g e 11 | 11