Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Define resistance and use the resistivity formula.
• Apply Ohm's Law to solve for V, I, and R.
• Calculate total resistance in series and parallel circuits.
• Analyse simple series and parallel circuits.
• Describe the safe use of multimeters.

Lesson summary

Welcome to Week 6! This week is dedicated to revision and examination preparation, focusing on solidifying your understanding of the concepts covered so far in Grade 10 Electrical Technology. Electrical Technology is incredibly relevant in South Africa. From the electricity that powers our homes and businesses to the technology used in our industries, understanding these principles is crucial for future engineers, technicians, and even informed consumers. This revision period will ensure you're well-prepared for upcoming assessments and have a strong foundation for future learning.

Lesson notes

This section will cover the key concepts we've learnt so far, with particular emphasis on resistors and circuits. 2.1 Resistance: Resistance (measured in Ohms, denoted by the symbol Ω) is the opposition to the flow of electric current in a circuit. Materials that offer high resistance are called insulators (e.g., rubber, plastic), while materials that offer low resistance are called conductors (e.g., copper, aluminium). Resistors are electronic components designed to provide a specific amount of resistance.

Factors affecting Resistance: The resistance of a conductor depends on: Length (L): Longer conductors have higher resistance.

Cross-sectional Area (A): Thicker conductors have lower resistance. Material (ρ - resistivity): Different materials have different resistivities. Resistivity is a material property that indicates how strongly a material resists electrical current. Copper has a low resistivity, while nichrome has a higher resistivity.

Temperature (T): For most conductors, resistance increases with temperature.

Resistivity Formula: The relationship between these factors is given by: R = ρL/A Where: R is the resistance (in Ohms, Ω) ρ is the resistivity (in Ohm-meters, Ω·m) L is the length (in meters, m) A is the cross-sectional area (in square meters, m 2 )