Technical Science - Term 4 - Week 6

An electrical circuit is a closed loop that allows electric current to flow. The basic components of a circuit include a power source (like a battery), conductors (wires), and load devices (like bulbs or resistors). Understanding these components is crucial for analyzing how circuits function.

There are two primary types of circuits: series and parallel. In a series circuit, components are connected end-to-end, meaning the same current flows through all components. In contrast, a parallel circuit has multiple paths for current to flow, allowing components to operate independently. This distinction is vital for understanding how circuits behave under different conditions.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. The formula is V = I × R. This law helps us calculate the values of voltage, current, or resistance when the other two are known, enabling us to analyze circuit behavior effectively.

Consider a series circuit with a 12V battery and two resistors of 4Ω and 6Ω. The total resistance (R_total) is R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, the current (I) can be calculated as I = V/R_total = 12V/10Ω = 1.2A. This means that 1.2A flows through the entire circuit.

In a parallel circuit with a 12V battery and two resistors of 4Ω and 6Ω, the total resistance can be calculated using the formula 1/R_total = 1/R1 + 1/R2. Thus, 1/R_total = 1/4 + 1/6 = 5/12, leading to R_total = 12/5 = 2.4Ω. The current through each resistor can then be calculated using Ohm's Law.

Given a series circuit with a 9V battery and two resistors of 3Ω and 5Ω, calculate the total resistance and the current flowing through the circuit. First, find the total resistance: R_total = 3Ω + 5Ω = 8Ω. Then, apply Ohm's Law: I = V/R_total = 9V/8Ω = 1.125A. Students should work through similar problems in pairs.

Students will complete a worksheet with various circuit scenarios. They will calculate total resistance, current, and voltage drops in both series and parallel circuits. For example, they might be given a circuit with a 24V battery and three resistors in series (2Ω, 3Ω, and 5Ω) and asked to find the current flowing through the circuit.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

Resistance is measured in Ohms, which quantifies how much a material opposes the flow of electric current.

• The same through all components
• Different in each component
• Zero
• Only flows through the first component

Answer: The same through all components

In a series circuit, the same current flows through each component because they are connected end-to-end.

• Components share the same current
• Components have multiple paths for current
• All components must be functional for the circuit to work
• Current is divided equally among components

Answer: Components have multiple paths for current

In a parallel circuit, each component is connected to the same voltage source, allowing current to flow through multiple paths.

Answer: V = I × R

Ohm's Law states that voltage (V) is equal to the product of current (I) and resistance (R).

Answer: 3A

Using Ohm's Law, I = V/R = 15V/5Ω = 3A.

• It increases
• It decreases
• It remains the same
• It becomes infinite

Answer: It decreases

Adding more resistors in parallel provides additional paths for current, which decreases the total resistance.

Answer: 10Ω

In a series circuit, total resistance is the sum of the individual resistances: 4Ω + 6Ω = 10Ω.