Technical Science - Term 4 - Week 3

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 loads (like light bulbs or resistors). Understanding how these components work together 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, so the same current flows through all components. In contrast, a parallel circuit has multiple paths for current to flow, meaning that the voltage across each component is the same. This distinction affects how circuits behave when components are added or removed.

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 relationship allows us to calculate one of these values if the other two are known, making it essential for circuit analysis.

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 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 = 5/12, leading to R_total = 12/5 = 2.4Ω. The current through the 4Ω resistor is I = V/R = 12V/4Ω = 3A, and through the 6Ω resistor, it is I = 12V/6Ω = 2A.

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 12V battery and two resistors of 2Ω and 3Ω. Calculate the total resistance and the current through each resistor. 2) A series circuit has a 24V battery and three resistors of 2Ω, 3Ω, and 5Ω. Find the total 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 one component

Answer: The same through all components

In a series circuit, the same current flows through each component because there is only one path for the current to take.

• It increases
• It decreases
• It stays the same
• It doubles

Answer: It decreases

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

Answer: V = I × R

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

Answer: 2A

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

• Resistor
• Capacitor
• Inductor
• Transistor

Answer: Capacitor

A capacitor is designed to store electrical energy in an electric field.

• Different
• The same
• Zero
• Only through one component

Answer: The same

In a parallel circuit, each component experiences the same voltage as the power source.