Physics - Term 2 - Week 6

An electric circuit is a closed loop that allows electric current to flow. It consists of various components such as resistors, capacitors, and power sources. The flow of current is driven by voltage, which is the potential difference between two points in the circuit. Understanding how these components interact is crucial for analyzing and designing circuits.

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 can be expressed with the formula V = I × R. This law is fundamental in calculating the behavior of circuits.

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 can be calculated using the formula 1/R_total = 1/R1 + 1/R2 + ... + 1/Rn. Understanding these configurations is essential for circuit analysis.

Consider a circuit with a voltage of 12V and a resistance of 4Ω. To find the current, we apply Ohm's Law: I = V/R = 12V / 4Ω = 3A. This means that a current of 3 amperes flows through the circuit.

If we have three resistors in series: R1 = 2Ω, R2 = 3Ω, and R3 = 5Ω, the total resistance (R_total) can be calculated as R_total = R1 + R2 + R3 = 2Ω + 3Ω + 5Ω = 10Ω.

For resistors R1 = 6Ω and R2 = 3Ω in parallel, the total resistance is calculated using the formula 1/R_total = 1/R1 + 1/R2. Thus, 1/R_total = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, leading to R_total = 2Ω.

Given a circuit with a voltage of 24V and a resistance of 8Ω, calculate the current flowing through the circuit. Students should use the formula I = V/R and find that I = 24V / 8Ω = 3A.

Students will work in pairs to calculate the total resistance of a series circuit with resistors of 4Ω, 6Ω, and 10Ω. They should find that R_total = 4Ω + 6Ω + 10Ω = 20Ω.

In groups, students will calculate the total resistance of two resistors in parallel: R1 = 12Ω and R2 = 4Ω. They should arrive at R_total = 1/(1/12 + 1/4) = 3Ω.

Students will complete a worksheet where they will calculate current, voltage, and resistance for various circuits using Ohm's Law. They will be given different values for voltage and resistance and must find the corresponding current.

Students will design a simple series circuit with three resistors of their choice and calculate the total resistance. They will then present their findings to the class.

Students will create a parallel circuit diagram with at least two resistors, calculate the total resistance, and explain their reasoning. They will submit their diagrams and calculations for assessment.

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

Answer: V = I × R

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

• R_total = R1 + R2 + R3
• R_total = 1/(1/R1 + 1/R2)
• R_total = R1 × R2
• R_total = R1 - R2

Answer: R_total = R1 + R2 + R3

In a series circuit, the total resistance is the sum of all individual resistances.

• It increases
• It decreases
• It remains the same
• It doubles

Answer: It decreases

Adding more resistors in parallel decreases the total resistance.

Answer: 2A

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

Answer: 10Ω

In series, R_total = R1 + R2 = 4Ω + 6Ω = 10Ω.

Answer: 2Ω

Using the formula 1/R_total = 1/R1 + 1/R2, we find R_total = 2Ω.

• Volt
• Ampere
• Ohm
• Watt

Answer: Ohm

Resistance is measured in ohms (Ω).

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

Answer: It doubles