Two resistors of 8 Ω and 12 Ω are connected in series with a 1... | General Science MCQ | Examoogle

General SciencePhysics: Electricity

Two resistors of 8 Ω and 12 Ω are connected in series with a 10 V battery. What is the current flowing through the circuit?

0.5 A

1.0 A

2.0 A

0.2 A

Correct Answer

⚙️ TE • Technical Concept & PrincipleGeneral SciencePhysics: Electricity

Option A

0.5 A

Quick Summary:

The correct answer is 0.5 A. In a series circuit, the total resistance is the sum of individual resistances, and the current remains constant throughout the path, determined by Ohm's Law.

🔬SCScience SolutionConcept & Principle

💡 Explanation

The correct answer is 0.5 A. In a series circuit, the total resistance is the sum of individual resistances, and the current remains constant throughout the path, determined by Ohm's Law.

💡 Everyday Analogy (Real-World Intuition)

Think of resistors in series as a series of narrow pipes in a single water line; the water (current) experiences total resistance by passing through each constriction sequentially.

🧠 Memory Mnemonic / Shortcut Aid

V-I-R (Vir): Voltage equals Current times Resistance.

🔢 Key Formulas

$R_{\text{eq}} = R_1 + R_2 +... + R_n$ — Total resistance in series

$I = \frac{V}{R_{\text{eq}}}$ — Ohm's Law for circuit current

⚙️ Working Principle

When resistors are connected in series, the total equivalent resistance ( $R_{\text{eq}}$ ) is calculated as $R_{\text{eq}} = R_1 + R_2$ . Once $R_{\text{eq}}$ is found, the current ( $I$ ) flowing through the entire circuit is calculated using Ohm's Law, which states $I = \frac{V}{R_{\text{eq}}}$ , where $V$ is the voltage of the battery.

📌 Key Points

▸
In a series circuit, current ( $I$ ) is the same through all components.
▸
Total resistance ( $R_{\text{eq}}$ ) in series is always greater than any individual resistor.
▸
Voltage ( $V$ ) is divided across resistors proportional to their resistance values.

✅ Advantages

▸
Simple circuit construction
▸
Current remains consistent regardless of resistor placement

❌ Disadvantages / Limitations

▸
If one component fails, the entire circuit is broken
▸
Voltage drops across each resistor reduce the potential available to others

🛠️ Applications / Uses

▸
String lights (traditional types)
▸
Voltage dividers in electronic circuits

📄 Additional Information

▸
Total resistance = $8 \, \Omega + 12 \, \Omega = 20 \, \Omega$ .
▸
Current = $\frac{10 \, \text{V}}{20 \, \Omega} = 0.5 \, \text{A}$ .
▸
Option B (1.0 A) is incorrect as it assumes $R = 10 \, \Omega$ ; Option C (2.0 A) assumes $R = 5 \, \Omega$ ; Option D (0.2 A) assumes $R = 50 \, \Omega$ .

📊 Diagram / Illustration

✅

A is correct — The total resistance of the series circuit is $20 \, \Omega$ , and applying Ohm's Law with a $10 \, \text{V}$ source yields a current of $0.5 \, \text{A}$ .

Core Concepts Used

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Ohm's Law Series resistance Electric current

💡 EXAM TIP

Always verify if the resistors are in series or parallel before calculating total resistance; series adds directly, while parallel uses the reciprocal sum rule $\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2}$ .

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