Technical Science - Term 4 - Week 1

An electrical circuit consists of various components that work together to allow the flow of electric current. The main components include resistors, capacitors, inductors, and power sources such as batteries. Resistors limit the flow of current, capacitors store electrical energy, and inductors oppose changes in current. 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, so the same current flows through all components. If one component fails, the entire circuit is interrupted. In contrast, a parallel circuit has multiple paths for current to flow. If one path fails, current can still flow through other paths, making parallel circuits more reliable in many applications.

Ohm's Law is a fundamental principle in electrical engineering 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 relationship allows us to calculate unknown values in a circuit.

Consider a series circuit with two resistors: R1 = 4 ohms and R2 = 6 ohms. The total resistance (R_total) in a series circuit is the sum of the individual resistances. Therefore, R_total = R1 + R2 = 4 + 6 = 10 ohms. If the circuit has a voltage supply of 20 volts, we can use Ohm's Law to find the current: I = V / R_total = 20 / 10 = 2 amperes.

In a parallel circuit with two branches, one with a resistor of 10 ohms and the other with 5 ohms, the voltage across each branch is the same. If the total current supplied is 6 amperes, we can find the current through each branch using Ohm's Law. For the 10-ohm resistor, I1 = V / R1, and for the 5-ohm resistor, I2 = V / R2. If we assume V = 10 volts, then I1 = 10 / 10 = 1 ampere and I2 = 10 / 5 = 2 amperes.

Let's work together on a problem. We have a series circuit with a 12-volt battery and three resistors: R1 = 2 ohms, R2 = 3 ohms, and R3 = 5 ohms. First, calculate the total resistance: R_total = R1 + R2 + R3 = 2 + 3 + 5 = 10 ohms. Now, apply Ohm's Law to find the total current: I = V / R_total = 12 / 10 = 1.2 amperes. Discuss how the current would change if one of the resistors was removed.

Now it's your turn to practice! Solve the following problems: 1) A circuit has a 9-volt battery and two resistors in series: R1 = 3 ohms and R2 = 6 ohms. Calculate the total current. 2) In a parallel circuit with a 12-volt battery and two resistors (R1 = 4 ohms and R2 = 12 ohms), calculate the current through each resistor. Show your work and be prepared to discuss your answers.

• 10 ohms
• 5 ohms
• 3 ohms
• 2 ohms

Answer: 10 ohms

In a series circuit, total resistance is the sum of all resistances: 2 + 3 + 5 = 10 ohms.

• Resistor
• Capacitor
• Inductor
• Transistor

Answer: Capacitor

A capacitor is designed to store electrical energy in an electric field.

Answer: V = I × R

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

• The entire circuit fails
• Only that component fails
• Current increases
• Voltage decreases

Answer: Only that component fails

In a parallel circuit, other paths remain available for current to flow if one component fails.

Answer: 3 amperes

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

• 8 volts
• 2 volts
• 6 volts
• 4 volts

Answer: 8 volts

Using Ohm's Law, V = I × R = 2 × 4 = 8 volts.

Answer: 2 amperes

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

• Series
• Parallel
• Combination