Technical Science - Term 4 - Week 8

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 loads (like resistors or light bulbs). Understanding how these components interact is crucial for analyzing and designing circuits.

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

In a series circuit, components are connected end-to-end, meaning the same current flows through each component. The total resistance is the sum of individual resistances. In contrast, a parallel circuit has components connected across the same voltage source, allowing multiple paths for current. The total resistance in a parallel circuit is less than the smallest individual resistance, which affects how the circuit behaves under load.

Consider a circuit with a voltage of 12 volts and a resistance of 4 ohms. To find the current, we apply Ohm's Law: I = V / R. Thus, I = 12V / 4Ω = 3A. This means the circuit allows a current of 3 amperes to flow.

If we have three resistors in series: R1 = 2Ω, R2 = 3Ω, and R3 = 5Ω, the total resistance (R_total) is R1 + R2 + R3 = 2Ω + 3Ω + 5Ω = 10Ω. This total resistance affects the current flowing through the circuit when connected to a voltage source.

For resistors in parallel, the formula is 1/R_total = 1/R1 + 1/R2 + 1/R3. If R1 = 4Ω, R2 = 4Ω, and R3 = 4Ω, we calculate: 1/R_total = 1/4 + 1/4 + 1/4 = 3/4. Therefore, R_total = 4/3Ω, which is approximately 1.33Ω. This lower resistance allows more current to flow compared to a series circuit.

Let's work together to find the current in a circuit with a voltage of 24 volts and a resistance of 6 ohms. Using Ohm's Law, we have I = V / R. Plugging in the values, I = 24V / 6Ω = 4A. Now, try calculating the current if the resistance is increased to 12 ohms.

In pairs, discuss the following circuit configurations: one with three light bulbs in series and another with three light bulbs in parallel. Identify how the current behaves in each case and what happens if one bulb fails. Share your findings with the class.

Using the resistors R1 = 10Ω, R2 = 5Ω, and R3 = 15Ω, calculate the total resistance for both series and parallel configurations. Work in groups and compare your answers. Remember to apply the correct formulas for each configuration.

Individually, calculate the current flowing through a circuit with a voltage of 30 volts and a resistance of 10 ohms. Show your work and explain your reasoning. Additionally, create a similar problem for a classmate to solve.

Design a simple circuit using two resistors in series and one in parallel. Specify the values of the resistors and the voltage source. Calculate the total resistance and current for your circuit. Be prepared to present your design to the class.

Research a real-world application of series and parallel circuits, such as in household wiring or electronic devices. Write a short paragraph explaining how the circuit type is used and its advantages. Share your findings with the class.

• 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.

• The sum of individual resistances
• The average of individual resistances
• The product of individual resistances
• Always equal to the smallest resistance

Answer: The sum of individual resistances

In a series circuit, the total resistance is calculated by adding all individual resistances together.

Answer: The total current remains the same, but the current through the failed component becomes zero.

In a parallel circuit, if one component fails, the other paths still allow current to flow.

• 4A
• 3A
• 2A
• 1A

Answer: 4A

Using Ohm's Law, I = V / R = 12V / 3Ω = 4A.

• They share the same current.
• They share the same voltage.
• The total resistance is greater than any individual resistance.
• They must have the same resistance value.

Answer: They share the same voltage.

In a parallel circuit, all components are connected across the same voltage source.

Answer: Total resistance is the equivalent resistance that affects the overall current flow in the circuit.

It determines how much current will flow for a given voltage applied to the circuit.