Technical Science - Term 1 - Week 4

An electrical circuit consists of several key components: a power source (like a battery), conductors (wires), and loads (devices that use electricity, such as bulbs or resistors). The power source provides the necessary voltage to push electric current through the circuit. Conductors allow the flow of electricity, while loads convert electrical energy into other forms of energy, such as light or heat.

There are two main types of circuits: series and parallel. In a series circuit, components are connected end-to-end, meaning the same current flows through each component. If one component fails, the entire circuit is interrupted. In contrast, a parallel circuit has multiple paths for current to flow. If one path fails, current can still flow through other paths, allowing the circuit to remain operational.

Ohm's Law is a fundamental principle in electrical engineering that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed by the formula V = I × R. This law allows us to calculate one of the three variables if the other two are known. Understanding Ohm's Law is crucial for analyzing and designing electrical circuits.

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, we find the current: I = V / R_total = 12V / 10Ω = 1.2A. This means 1.2A flows through each component in the series circuit.

In a parallel circuit with a 12V battery and two resistors of 4Ω and 6Ω, we first calculate the total resistance using the formula 1/R_total = 1/R1 + 1/R2. This gives us 1/R_total = 1/4 + 1/6, which simplifies to R_total = 2.4Ω. Now, applying Ohm's Law, the total current is I = V / R_total = 12V / 2.4Ω = 5A. Each branch will have a different current based on its resistance.

Let's work through a problem together. We have a series circuit with a 9V battery and three resistors: 2Ω, 3Ω, and 5Ω. First, calculate the total resistance: R_total = 2Ω + 3Ω + 5Ω = 10Ω. Now, apply Ohm's Law to find the current: I = V / R_total = 9V / 10Ω. What is the current flowing through the circuit?

Now it's your turn! Solve the following problems independently: 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 two resistors of 3Ω and 7Ω, find the current flowing through the circuit. Show all your calculations.

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

Answer: To limit current flow

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

• The circuit remains operational
• The circuit is interrupted
• Only the failed component stops working
• The voltage increases

Answer: The circuit is interrupted

In a series circuit, all components are connected in a single path, so a failure in one component stops the entire current flow.

Answer: V = I × R

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

• 15Ω
• 5Ω
• 10Ω
• 20Ω

Answer: 15Ω

In a series circuit, total resistance is the sum of all resistances: 5Ω + 10Ω = 15Ω.

Answer: The total current increases.

Adding more branches in a parallel circuit provides additional paths for current, which increases the total current.

• Current is the same through all components
• Voltage is the same across all components
• Total resistance increases with more components
• All components must be functioning for the circuit to work

Answer: Voltage is the same across all components

In parallel circuits, the voltage across each component is the same, while the current can vary.