Physics - Term 3 - Week 7

Electric circuits are pathways that allow electric current to flow. The three fundamental components of an electric circuit are voltage (V), current (I), and resistance (R). Voltage is the potential difference that drives current through the circuit, measured in volts. Current is the flow of electric charge, measured in amperes (A), while resistance is the opposition to current flow, measured in ohms (Ω). Ohm's Law, which states that V = I × R, is essential for understanding how these components interact.

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 individual resistances (R_total = R1 + R2 + ... + Rn). In contrast, in a parallel circuit, components are connected across the same voltage source, and the total current is the sum of the currents through each component. The total resistance in a parallel circuit can be calculated using the formula 1/R_total = 1/R1 + 1/R2 + ... + 1/Rn.

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. Thus, I = 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 can be calculated as R_total = R1 + R2 + R3 = 2Ω + 3Ω + 5Ω = 10Ω. Therefore, the total resistance of the series circuit is 10 ohms.

Given a circuit with a voltage of 24V and a resistance of 6Ω, calculate the current flowing through the circuit. Use Ohm's Law: I = V/R. Students should work in pairs to solve this problem and discuss their findings.

Consider a parallel circuit with two resistors: R1 = 4Ω and R2 = 12Ω. Guide the students through the calculation of total resistance using the formula 1/R_total = 1/R1 + 1/R2. After calculating, they should compare their answers with a partner.

Students will complete a worksheet with various problems involving Ohm's Law and calculations for both series and parallel circuits. Problems will include finding current, voltage, and total resistance in different configurations. Encourage students to show all their work and reasoning.

Students will design a simple circuit diagram that includes at least two resistors in series and two in parallel. They will calculate the total resistance and current for their circuit, presenting their findings to the class.

• Volts
• Amperes
• Ohms
• Watts

Answer: Amperes

The unit of electric current is measured in Amperes (A).

• Less than the smallest resistor
• Equal to the sum of all resistors
• The same as the largest resistor
• None of the above

Answer: Equal to the sum of all resistors

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

Answer: V = I × R

Ohm's Law states that the voltage (V) across a conductor is equal to the current (I) flowing through it multiplied by the resistance (R).

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

Answer: It increases

In a parallel circuit, adding more branches increases the total current because each branch provides an additional path for current to flow.

Answer: 2A

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

• They share the same current
• They share the same voltage
• They have the same resistance
• None of the above

Answer: They share the same voltage

In a parallel circuit, all components share the same voltage across them.

Answer: 2Ω

Using the formula 1/R_total = 1/R1 + 1/R2, we get 1/R_total = 1/3 + 1/6 = 1/2, thus R_total = 2Ω.