Technical Science - Term 2 - Week 10

An electrical circuit is a closed loop that allows current to flow from a power source to various components and back. The basic components of a circuit include a power source (like a battery), conductors (wires), and load devices (like bulbs or resistors). Understanding how these components interact is crucial for analyzing and designing circuits.

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. In contrast, a parallel circuit has components connected across common points, allowing multiple paths for current to flow. This distinction affects how voltage and current are distributed in the circuit.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. The law is expressed as V = I × R. This relationship allows us to calculate one of the three quantities if the other two are known, making it essential for circuit analysis.

Consider a series circuit with a 12V battery and two resistors of 4Ω and 6Ω. The total resistance (R_total) is the sum of the individual resistances: R_total = 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. Therefore, the current in a series circuit is the same through all components.

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, which simplifies to R_total = 2.4Ω. The current through each resistor can then be calculated using Ohm's Law, showing that the voltage across each component is the same as the source voltage.

Let's analyze a circuit together. Imagine a circuit with a 9V battery and three resistors: 3Ω, 6Ω, and 9Ω connected in series. First, calculate the total resistance. Next, use Ohm's Law to find the current flowing through the circuit. Finally, determine the voltage drop across each resistor using the formula V = I × R.

Now it's your turn to practice. Solve the following problems: 1) A circuit has a 24V battery and two resistors of 8Ω and 4Ω in series. Calculate the total resistance and the current. 2) In a parallel circuit with a 12V battery and two resistors of 12Ω and 6Ω, find the total resistance and the current through each resistor.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

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

• Different at each component
• The same at all components
• Zero
• Variable depending on voltage

Answer: The same at all components

In a series circuit, the same current flows through each component.

• 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.

Answer: V = I × R

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

• Different
• The same as the source voltage
• Zero
• Dependent on the resistance

Answer: The same as the source voltage

In a parallel circuit, all components share the same voltage from the power source.

Answer: 2A

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

• 2.4Ω
• 10Ω
• 24Ω
• 1.5Ω

Answer: 2.4Ω

The total resistance in parallel is calculated using 1/R_total = 1/R1 + 1/R2, which gives 2.4Ω.