Technical Science - Term 3 - Week 9

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 motors). The power source provides the necessary voltage to push the current through the circuit. Conductors allow the flow of electricity, while loads convert electrical energy into other forms of energy, such as light or motion.

There are two primary types of electrical circuits: series and parallel. In a series circuit, components are connected end-to-end, so the same current flows through all components. 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 functional.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed by the formula V = I × R. This means that the voltage across a conductor is directly proportional to the current flowing through it, provided the temperature remains constant. Understanding this relationship allows for the calculation of any one of the three variables if the other two are known.

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 in the circuit 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, giving R_total = 12/5 = 2.4Ω. The current through the circuit can be calculated as I = V / R_total = 12V / 2.4Ω = 5A. This current is divided among the branches of the circuit.

Let's work through a problem together. You have a series circuit with a 9V battery and two resistors of 3Ω and 3Ω. First, calculate the total resistance. Then, use Ohm's Law to find the current flowing through the circuit. Discuss your findings with a partner and compare your calculations.

Look at the diagrams of two circuits provided. One is a series circuit, and the other is a parallel circuit. Work in pairs to identify which is which and explain your reasoning. Consider how the failure of one component would affect each type of circuit.

Complete the following problems on your own: 1) A circuit has a 24V battery and three resistors of 2Ω, 3Ω, and 5Ω in series. Calculate the total resistance and the current. 2) A parallel circuit has a 12V battery and two resistors of 6Ω and 12Ω. Calculate the total current flowing from the battery. Show all your work and be prepared to discuss your answers.

Design a simple circuit diagram that includes at least one power source, two resistors, and a load. Label all components and indicate whether it is a series or parallel circuit. Write a brief explanation of how the circuit works and the expected current flow.

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

Answer: To limit current flow

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

• The circuit remains functional
• 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 if one fails, the entire circuit stops working.

Answer: V = I × R

Ohm's Law states that voltage equals current multiplied by resistance.

• 10Ω
• 5Ω
• 3Ω
• 2Ω

Answer: 10Ω

In a series circuit, total resistance is the sum of all resistances: 2Ω + 3Ω + 5Ω = 10Ω.

• Current is the same through all components
• Voltage is the same across all components
• Resistance is the same across all components
• All components must be functional 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.

Answer: 2A

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

• It increases
• It decreases