Technical Science - Term 4 - Week 2

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

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed with the formula V = I × R. This law allows us to calculate one of these values if the other two are known. For example, if a circuit has a voltage of 12 volts and a resistance of 4 ohms, the current can be calculated as I = V/R = 12V/4Ω = 3A.

Circuits can be classified into two main types: 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. Understanding the differences between these types is essential for circuit analysis.

Consider a circuit with a voltage of 24 volts and a resistance of 6 ohms. To find the current, we use Ohm's Law: I = V/R. Substituting the values, we get I = 24V / 6Ω = 4A. Therefore, the current flowing through the circuit is 4 amperes.

In a series circuit with three resistors of 2Ω, 3Ω, and 5Ω, the total resistance can be calculated by adding the resistances: R_total = R1 + R2 + R3 = 2Ω + 3Ω + 5Ω = 10Ω. If the circuit is powered by a 20V battery, the current can be found using Ohm's Law: I = V/R_total = 20V / 10Ω = 2A.

Let's work through a problem together. If we have a circuit with a current of 5A flowing through a resistor of 10Ω, what is the voltage across the resistor? Using Ohm's Law, V = I × R, we substitute the values: V = 5A × 10Ω = 50V. Therefore, the voltage across the resistor is 50 volts.

Consider a parallel circuit with two resistors: R1 = 4Ω and R2 = 6Ω. To find the total resistance (R_total) in a parallel circuit, we use the formula 1/R_total = 1/R1 + 1/R2. Substituting the values gives us 1/R_total = 1/4 + 1/6. Finding a common denominator, we get R_total = 2.4Ω. This is the total resistance of the parallel circuit.

Now it's your turn! Calculate the current flowing through a circuit with a voltage of 30V and a resistance of 15Ω. Use Ohm's Law to find the answer. Additionally, analyze a series circuit with two resistors of 3Ω and 7Ω connected to a 20V battery. What is the total resistance and the current flowing through the circuit?

Solve the following problems independently: 1) A circuit has a current of 2A and a resistance of 5Ω. What is the voltage? 2) In a parallel circuit with resistors of 8Ω and 4Ω, calculate the total resistance. 3) If a circuit has a voltage of 12V and a total resistance of 3Ω, what is the current?

• V = I + R
• V = I × R
• V = I / R
• V = R / I

Answer: V = I × R

Ohm's Law states that voltage equals current multiplied by resistance.

• It splits between components
• It is the same through all components
• It increases at each component
• It decreases at each component

Answer: It is the same through all components

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

Answer: A parallel circuit is a type of circuit where components are connected across common points, allowing multiple paths for current to flow.

This definition captures the essence of how parallel circuits function.

• 2.4Ω
• 10Ω
• 24Ω
• 1.5Ω

Answer: 2.4Ω

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

Answer: 3A

Using Ohm's Law, I = V/R = 24V/8Ω = 3A.

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

Answer: It increases

Adding more resistors in series increases the total resistance.

Answer: 20V

Using Ohm's Law, V = I × R = 4A × 5Ω = 20V.