Technical Science - Term 1 - Week 10

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 electrons 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, meaning the same current flows through each component. If one component fails, the entire circuit is interrupted. In contrast, a parallel circuit has multiple paths for current to flow. If one path is broken, current can still flow through other paths, allowing the circuit to remain functional.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It states that 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 crucial for analyzing and designing electrical circuits.

Consider a simple series circuit with a 12V battery and two resistors of 4Ω and 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. This means that 1.2A flows through both resistors.

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 = 3/12 + 2/12 = 5/12, leading to 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.

Let's work through a problem together. We have a series circuit with a 9V battery and three resistors of 2Ω, 3Ω, and 5Ω. First, calculate the total resistance: R_total = 2Ω + 3Ω + 5Ω = 10Ω. Now, apply Ohm's Law to find the current: I = V / R_total = 9V / 10Ω. What is the current flowing through the circuit?

Now it's your turn! Solve the following problems independently: 1) A parallel circuit has a 24V battery and two resistors of 8Ω and 12Ω. Calculate the total resistance and the current. 2) In a series circuit with a 15V battery and two resistors of 3Ω and 9Ω, find the current flowing through the circuit. Show your calculations clearly.

• To store electrical energy
• To limit current flow
• To increase voltage
• To convert energy to light

Answer: To limit current flow

Resistors are used to control the flow of current in a circuit by providing resistance.

• The circuit remains functional
• The circuit is interrupted
• Only the failed component stops working
• The voltage increases

Answer: The circuit is interrupted

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

Answer: V = I × R

Ohm's Law states that voltage is equal to the current multiplied by resistance.

• 2.4Ω
• 10Ω
• 24Ω
• 12Ω

Answer: 2.4Ω

The total resistance in a parallel circuit is calculated using the formula 1/R_total = 1/R1 + 1/R2.

Answer: 2A

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

• Resistor
• Capacitor
• Inductor
• Transistor

Answer: Capacitor

Capacitors are used to store electrical energy in an electric field.

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

Answer: It increases

Adding more resistors in series increases the total resistance of the circuit.