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 motors). The power source provides the energy needed for the circuit to function. Conductors allow the flow of electric current, while loads convert electrical energy into other forms of energy, such as light or motion.

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. 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 continue functioning.

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 as 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 law is essential for analyzing and designing circuits.

Consider a series circuit with a 12V battery and two resistors: R1 = 4Ω and R2 = 6Ω. The total resistance (R_total) in a series circuit is the sum of individual resistances: R_total = R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, the current (I) can be calculated as I = V / R_total = 12V / 10Ω = 1.2A. Therefore, the current flowing through the circuit is 1.2A.

In a parallel circuit with a 12V battery and two resistors: R1 = 4Ω and R2 = 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 = 3/12 + 2/12 = 5/12, which gives R_total = 12/5 = 2.4Ω. The current through the circuit can be calculated using Ohm's Law: I = V / R_total = 12V / 2.4Ω = 5A.

Now, let's practice together. You have a series circuit with a 9V battery and two resistors: R1 = 3Ω and R2 = 3Ω. First, calculate the total resistance. Then, use Ohm's Law to find the current flowing through the circuit. Remember, R_total = R1 + R2. What is the total resistance, and what is the current?

Look at the following circuit diagrams displayed on the board. Identify which ones are series circuits and which are parallel circuits. Discuss with your partner why you classified them as such. Pay attention to the paths of the current and how the components are connected.

For your independent practice, create your own circuit diagram using at least three components. Label each component and indicate whether it is in series or parallel. Then, calculate the total resistance and the current flowing through the circuit if a 15V battery is used. Be prepared to present your circuit to the class.

Complete the worksheet provided, which includes various problems involving Ohm's Law. You will need to calculate voltage, current, and resistance for different scenarios. Ensure you show all your workings for full credit.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

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

• Only that component stops working
• The entire circuit is interrupted
• Current increases
• Voltage decreases

Answer: The entire circuit is interrupted

In a series circuit, all components are connected in a single path, so if one fails, the current cannot flow through the circuit.

Answer: V = I × R

Ohm's Law states that the voltage across a conductor is equal to the current flowing through it multiplied by the resistance.

• Same current flows through all components
• Total resistance is the sum of individual resistances
• If one component fails, others can still function
• Current is always the same

Answer: If one component fails, others can still function

Parallel circuits allow multiple paths for current, so if one path fails, current can still flow through other paths.

Answer: 3A

Using Ohm's Law, I = V / R = 12V / 4Ω = 3A.

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

Answer: It increases

Adding more resistors in series increases the total resistance because the resistances add together.

• 5Ω
• 6Ω