Technical Science - Term 1 - Week 5

An electrical circuit consists of various components that work together to allow the flow of electricity. The main components include a power source (like a battery), conductors (wires), resistors (which limit current), and loads (devices that use electricity). Understanding these components is crucial for analyzing how circuits function.

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 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 behave in each type of circuit.

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 as V = I × R. This law allows us to calculate one of these values if the other two are known, making it essential for circuit analysis.

Consider a simple series circuit with a 12V battery and two resistors of 4Ω and 6Ω. To find the total resistance, we add the resistances: R_total = R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, we can find the current: I = V / R_total = 12V / 10Ω = 1.2A. This current 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 = 5/12, giving R_total = 12/5 = 2.4Ω. The current through the circuit can then be calculated as 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: 1) A circuit has a 24V battery and two resistors in series of 8Ω and 4Ω. Calculate the total resistance and the current. 2) In a parallel circuit with a 12V battery and two resistors of 3Ω and 6Ω, find the total current flowing from the battery. Show your calculations.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

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

• True
• It is not covered in this lesson.
• It applies only in later weeks.
• The opposite is true.
• None of the above.

Answer: True

In a series circuit, the voltage drops across each component add up to the total voltage supplied by the source.

Answer: V = I × R

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

• Capacitor
• Resistor
• Inductor
• Transistor

Answer: Resistor

A resistor is specifically designed to limit the flow of current in an electrical circuit.

Answer: The total resistance decreases.

Adding more resistors in parallel provides additional paths for current, which reduces the overall resistance.

• It doubles
• It halves
• It remains the same
• It quadruples

Answer: It doubles

According to Ohm's Law, if voltage increases while resistance stays the same, current will increase proportionally.

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