Technical Science - Term 3 - Week 2

An electrical circuit is a closed loop that allows current to flow from a power source to various components and back. Key components include resistors, capacitors, inductors, and power sources like batteries. Understanding these components is crucial for analyzing how circuits operate and how they can be manipulated for various applications.

There are two primary types of circuits: series and parallel. In a series circuit, components are connected end-to-end, meaning the same current flows through each component. In contrast, a parallel circuit has multiple paths for current to flow, allowing components to operate independently. This distinction affects how voltage and current are distributed across the circuit.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed as V = I × R. This relationship allows us to calculate one of the three variables if the other two are known, which is essential for designing and troubleshooting circuits.

Consider a series circuit with a 12V battery and two resistors, R1 = 4Ω and R2 = 6Ω. The total resistance (R_total) is R1 + R2 = 10Ω. Using Ohm's Law, the current (I) can be calculated as I = V / R_total = 12V / 10Ω = 1.2A. This current flows through both resistors, demonstrating how series circuits work.

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. This gives us 1/R_total = 1/4 + 1/6, leading to R_total = 2.4Ω. The current through each resistor can then be calculated using Ohm's Law, showing how voltage remains constant across parallel components.

Let's work through a problem together. We have a series circuit with a 9V battery and three resistors: R1 = 2Ω, R2 = 3Ω, and R3 = 4Ω. First, calculate the total resistance: R_total = R1 + R2 + R3. Then, use Ohm's Law to find the current. What is the total resistance and the current flowing through the circuit?

Now it's your turn! Solve the following problems: 1) A parallel circuit has a 12V battery and two resistors, R1 = 8Ω and R2 = 4Ω. Calculate the total resistance and the current through each resistor. 2) In a series circuit with a 15V battery and two resistors, R1 = 5Ω and R2 = 10Ω, find the current flowing through the circuit.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

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

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

Answer: The same at all points

In a series circuit, the same current flows through each component, as there is only one path for the current to take.

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

Answer: It decreases

Adding more resistors in parallel provides additional paths for current, which decreases the total resistance.

Answer: V = I × R

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

• 2A
• 5A
• 10A
• 15A

Answer: 2A

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

Answer: 8Ω

In a series circuit, total resistance is the sum of the individual resistances: R_total = R1 + R2 = 3Ω + 5Ω = 8Ω.

• Voltage is the same across all components
• Current is the same through all components
• Total resistance is the sum of individual resistances
• They are always more complex than series circuits

Answer: Voltage is the same across all components