Technical Science - Term 2 - Week 5

An electrical circuit consists of several key components: a power source (like a battery), conductors (wires), and loads (devices that use electricity, such as bulbs or motors). The power source provides the electrical energy needed to drive the current through the circuit. Conductors allow the flow of electric current, while loads convert electrical energy into other forms of energy, such as light or motion.

There are two main types of electrical circuits: series and parallel. In a series circuit, components are connected end-to-end, so the current flows through each component sequentially. If one component fails, the entire circuit is interrupted. In contrast, a parallel circuit has multiple paths for current to flow. If one path is interrupted, current can still flow through other paths, allowing the circuit to remain operational.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed by the formula V = I × R. This means that the voltage across a circuit is equal to the current flowing through it multiplied by the resistance. Understanding this relationship is crucial for analyzing and designing electrical circuits.

Suppose we have a circuit with a voltage of 12 volts and a current of 3 amperes. To find the resistance, we can rearrange Ohm's Law: R = V / I. Plugging in the values, we get R = 12V / 3A = 4 ohms. This means the resistance in the circuit is 4 ohms.

Consider a series circuit with two resistors: R1 = 2 ohms and R2 = 3 ohms. The total resistance in a series circuit is the sum of the individual resistances: R_total = R1 + R2 = 2Ω + 3Ω = 5Ω. If the circuit is powered by a 10V battery, we can find the current using Ohm's Law: I = V / R_total = 10V / 5Ω = 2A.

Let's analyze a parallel circuit with two resistors: R1 = 6 ohms and R2 = 3 ohms. The formula for total resistance in a parallel circuit is 1/R_total = 1/R1 + 1/R2. First, calculate 1/R_total = 1/6 + 1/3. Finding a common denominator, we get 1/R_total = 1/6 + 2/6 = 3/6. Thus, R_total = 6/3 = 2 ohms. Now, if the circuit is connected to a 12V battery, calculate the total current using I = V / R_total.

Now it's your turn! Solve the following problems: 1) A circuit has a voltage of 24V and a resistance of 8 ohms. Calculate the current. 2) In a series circuit with three resistors (R1 = 4 ohms, R2 = 6 ohms, R3 = 10 ohms), find the total resistance. 3) A parallel circuit has two resistors (R1 = 12 ohms, R2 = 4 ohms). Calculate the total resistance and the current if connected to a 20V battery.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

Resistance is measured in ohms, which quantifies how much a material opposes the flow of electric current.

• It continues to work
• It stops working
• Only the failed component stops
• The voltage increases

Answer: It stops working

In a series circuit, all components are connected in a single path, so if one fails, the entire circuit is interrupted.

Answer: V = I × R

Ohm's Law states that the voltage across a conductor is directly proportional to the current flowing through it, with resistance as the proportionality constant.

• 2 ohms
• 4 ohms
• 8 ohms
• 16 ohms

Answer: 2 ohms

For resistors in parallel, the total resistance is calculated using 1/R_total = 1/R1 + 1/R2, resulting in 2 ohms.

Answer: The current decreases.

According to Ohm's Law, if resistance increases while voltage remains constant, the current must decrease.

• Battery
• Resistor
• Capacitor
• Magnet

Answer: Magnet

While magnets can be used in some electrical applications, they are not standard components of an electrical circuit.

• 5 ohms
• 10 ohms
• 20 ohms