Technical Science - Term 3 - Week 8

An electrical circuit is a closed loop that allows electric current to flow. The main components of a circuit include a power source (like a battery), conductors (wires), and loads (devices that use electricity, such as bulbs or motors). Understanding how these components interact is crucial for analyzing and designing circuits.

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 components connected across common points, allowing multiple paths for current to flow. This distinction affects how voltage and current behave in each type.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed as V = I × R. This law allows us to calculate one of these values if the other two are known, which is essential for circuit analysis.

Consider a series circuit with a 12V battery and two resistors of 4Ω and 6Ω. First, calculate the total resistance: R_total = R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, the current can be calculated as I = V / R_total = 12V / 10Ω = 1.2A. This current flows through both resistors.

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, which simplifies to R_total = 2.4Ω. The current through the circuit can then be calculated as I = V / R_total = 12V / 2.4Ω = 5A.

Let's work through a problem together. We have a series circuit with a 9V battery and two resistors of 3Ω and 5Ω. First, calculate the total resistance: R_total = 3Ω + 5Ω = 8Ω. Now, apply Ohm's Law to find the current: I = V / R_total = 9V / 8Ω. What is the current flowing through the circuit?

Now it's your turn! Solve the following problems on your own: 1) A parallel circuit has a 24V battery and two resistors of 8Ω and 12Ω. Calculate the total current. 2) In a series circuit with a 15V battery and three resistors of 2Ω, 3Ω, and 5Ω, find the current flowing through the circuit. Show your calculations.

• To store electrical energy
• To limit current flow
• To increase voltage
• To convert AC to DC

Answer: To limit current flow

Resistors are used to control the amount of current that can flow through a circuit.

• Total voltage is equal to the sum of voltages across components
• Total voltage is less than the voltage across each component
• Total voltage is greater than the voltage across each component
• Total voltage is independent of component voltages

Answer: Total voltage is equal to the sum of voltages across components

In a series circuit, the total voltage is divided among the components.

Answer: V = I × R

Ohm's Law states that voltage (V) is equal to the current (I) multiplied by the resistance (R).

• It increases
• It decreases
• It remains the same
• It doubles

Answer: It decreases

Adding more resistors in parallel provides additional paths for current, reducing total resistance.

Answer: 2A

Using Ohm's Law, I = V / R = 10V / 5Ω = 2A.

• Resistor
• Capacitor
• Battery
• Transistor

Answer: Battery

A battery serves as the power source, providing the necessary voltage for the circuit.

Answer: In series circuits, components are connected end-to-end, sharing the same current. In parallel circuits, components are connected across common points, allowing multiple paths for current.