Technical Science - Term 2 - 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, while the conductors allow current to flow through the circuit. Understanding these components is crucial for analyzing how circuits operate.

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 by the formula V = I × R. This law allows us to calculate any one of these three quantities if the other two are known. Understanding Ohm's Law is essential for solving circuit problems and designing electrical systems.

Consider a series circuit with a 12V battery and two resistors: R1 = 4Ω and R2 = 6Ω. To find the total resistance (R_total), we add the resistances: R_total = R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, we can find the current (I) flowing through the circuit: I = V / R_total = 12V / 10Ω = 1.2A.

In a parallel circuit with a 12V battery and two resistors: R1 = 3Ω and R2 = 6Ω, the voltage across each resistor is the same as the battery voltage. Therefore, V = 12V for both R1 and R2. To find the current through each resistor, we use Ohm's Law: I1 = V / R1 = 12V / 3Ω = 4A and I2 = V / R2 = 12V / 6Ω = 2A.

Work in pairs to analyze a series circuit with a 9V battery and three resistors: R1 = 2Ω, R2 = 3Ω, and R3 = 5Ω. Calculate the total resistance, the current flowing through the circuit, and the voltage drop across each resistor. Discuss your findings with the class.

Complete the following problems on your own: 1) A circuit has a 24V battery and two resistors in series: R1 = 8Ω and R2 = 4Ω. Calculate the total resistance and current. 2) In a parallel circuit with a 12V battery and two resistors: R1 = 6Ω and R2 = 12Ω, find the current through each resistor. Show all calculations.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

Resistance is measured in Ohms, which is the standard unit in electrical engineering.

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

Answer: It stops working

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

Answer: V = I × R

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

• 10Ω
• 5Ω
• 3Ω
• 15Ω

Answer: 10Ω

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

Answer: The total current increases.

Adding more branches in a parallel circuit provides additional paths for current to flow, increasing the total current.

• Current is the same through all components
• Voltage is the same across all components
• Resistance is the same across all components
• All components are in a single path

Answer: Voltage is the same across all components

In a parallel circuit, the voltage across each component is equal to the source voltage.

Answer: 2A

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