Physics - Term 4 - Week 7

An electric circuit is a closed loop that allows electric current to flow. 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 essential for analyzing circuit behavior.

Ohm's Law states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) of the conductor. This relationship can be expressed with the formula V = I × R. This law is fundamental in circuit analysis.

In a series circuit, components are connected end-to-end, so the same current flows through each component. The total resistance in a series circuit is the sum of the individual resistances. In contrast, in a parallel circuit, components are connected across the same voltage source, and the total resistance is found using the formula 1/R_total = 1/R1 + 1/R2 + ... + 1/Rn.

If a circuit has a voltage of 12 volts and a resistance of 4 ohms, we can find the current using Ohm's Law. I = V/R = 12V/4Ω = 3A. This means that a current of 3 amperes flows through the circuit.

Consider a series circuit with three resistors: R1 = 2Ω, R2 = 3Ω, and R3 = 5Ω. The total resistance is R_total = R1 + R2 + R3 = 2Ω + 3Ω + 5Ω = 10Ω.

For a parallel circuit with two resistors, R1 = 6Ω and R2 = 3Ω, the total resistance can be calculated as follows: 1/R_total = 1/R1 + 1/R2 = 1/6 + 1/3 = 1/6 + 2/6 = 3/6. Therefore, R_total = 6/3 = 2Ω.

Using the formula V = I × R, calculate the voltage in a circuit where the current is 2A and the resistance is 5Ω. Students should show their calculations step by step, arriving at V = 2A × 5Ω = 10V.

Given a series circuit with resistors of 4Ω, 6Ω, and 10Ω, guide students to calculate the total resistance. They should add the resistances together: R_total = 4Ω + 6Ω + 10Ω = 20Ω.

In a parallel circuit with two resistors of 8Ω and 4Ω, guide students through the calculation of total resistance. They should set up the equation: 1/R_total = 1/8 + 1/4, leading to R_total = 8/3Ω.

Students will solve a series of problems involving Ohm's Law and circuit configurations. For instance, calculate the current in a circuit with a voltage of 24V and a resistance of 8Ω. They should also calculate the total resistance in a series circuit with resistors of 5Ω, 10Ω, and 15Ω.

Students will design a simple circuit using a battery, a switch, and two light bulbs in series and parallel. They will calculate the expected current and resistance for each configuration and discuss the implications of their designs.

Students will write a short paragraph reflecting on the differences between series and parallel circuits and their applications in real life, such as in household wiring.

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

Answer: V = I × R

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

• It splits between components
• It remains constant
• It increases
• It decreases

Answer: It remains constant

In a series circuit, the same current flows through all components.

• 2Ω
• 4Ω
• 8Ω
• 16Ω

Answer: 2Ω

For resistors in parallel, the total resistance is calculated using 1/R_total = 1/R1 + 1/R2.

Answer: 2A

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

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

Answer: It increases

Adding more resistors in series increases the total resistance.

Answer: 10Ω

Total resistance in series is the sum: 2Ω + 3Ω + 5Ω = 10Ω.

• The circuit stops working
• The current increases
• The total resistance decreases
• The other resistors remain unaffected

Answer: The other resistors remain unaffected

In a parallel circuit, if one resistor fails, current can still flow through the other paths.