Technical Science - Term 4 - 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 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 circuits: series and parallel. In a series circuit, components are connected end-to-end, so the same current flows through each component. If one component fails, the entire circuit is broken. 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 9V battery and two resistors of 3Ω and 6Ω. The total resistance (R_total) is R1 + R2 = 3Ω + 6Ω = 9Ω. Using Ohm's Law, we can find the current (I) flowing through the circuit: I = V / R_total = 9V / 9Ω = 1A. Therefore, the current flowing through the circuit is 1 ampere.

In a parallel circuit with a 12V battery and two resistors of 4Ω and 12Ω, the total resistance can be calculated using the formula 1/R_total = 1/R1 + 1/R2. This gives us 1/R_total = 1/4 + 1/12, which simplifies to R_total = 3Ω. The current through the circuit can be found using Ohm's Law: I = V / R_total = 12V / 3Ω = 4A.

Let's work together on a problem. We have a series circuit with a 12V battery and two resistors of 2Ω and 4Ω. First, calculate the total resistance: R_total = 2Ω + 4Ω = 6Ω. Now, apply Ohm's Law to find the current: I = V / R_total = 12V / 6Ω. What is the current flowing through the circuit?

Look at the following diagrams of circuits. Identify which are series and which are parallel. Discuss with your partner the characteristics that led you to your conclusions. Remember, in a series circuit, all components are connected in a single path, while in a parallel circuit, components are connected across common points.

Design your own simple circuit using a battery, two resistors, and a light bulb. Draw the circuit diagram and label all components. Calculate the total resistance and the current flowing through the circuit when connected to a 9V battery. Be prepared to present your design and calculations to the class.

Complete the following problems: 1) A circuit has a voltage of 24V and a resistance of 6Ω. Calculate the current. 2) If a circuit has a current of 3A and a resistance of 4Ω, what is the voltage? Show your work for each problem.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

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

• It continues to work
• It becomes short-circuited
• It stops working
• It increases current

Answer: It stops working

In a series circuit, all components are connected in a single path, so if one fails, the entire circuit is interrupted.

• Same current flows through all components
• Total resistance is less than the smallest resistor
• If one component fails, the circuit fails
• All components share the same voltage

Answer: Total resistance is less than the smallest resistor

In a parallel circuit, the total resistance is always less than the smallest individual resistor due to multiple pathways for current.

Answer: V = I × R

Ohm's Law states that voltage (V) is equal to the product of current (I) and resistance (R).

Answer: 2A

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

• It decreases
• It increases
• It remains the same
• It becomes zero

Answer: It increases

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

• 5Ω
• 10Ω
• 15Ω