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General SciencePhysics: Electricity

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Determine the current flowing through a 10 ohm resistor when connected to a 20 V DC source.

0.5 A

2 A

200 A

1 A

Correct Answer

⚙️ TE • Technical Concept & PrincipleGeneral SciencePhysics: Electricity

Option B

2 A

Quick Summary:

The current flowing through a resistor is directly proportional to the applied voltage and inversely proportional to its resistance, as defined by Ohm's Law. Given a voltage of $20 \text{ V}$ and a resistance of $10 \text{ } \Omega$ , the current is calculated as $I = \frac{20}{10} = 2 \text{ A}$ .

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of voltage as water pressure in a pipe and resistance as the width of the pipe; a wider pipe (lower resistance) or higher pressure (higher voltage) allows more water (current) to flow through.

🧠 Memory Mnemonic / Shortcut Aid

VIR: $V = I \times R$ (Very Important Rule).

🔢 Key Formulas

$V = I \times R$ — Ohm's Law, where $V$ is voltage, $I$ is current, and $R$ is resistance

$I = \frac{V}{R}$ — Formula to calculate current when voltage and resistance are known

⚙️ Working Principle

Ohm's Law states that the current ( $I$ ) flowing through a conductor between two points is directly proportional to the potential difference ( $V$ ) across the two points and inversely proportional to the resistance ( $R$ ). The formula is derived from $V = I \times R$ , which rearranges to $I = \frac{V}{R}$ . Here, the electromotive force drives electrons through the lattice of the resistor, where collisions result in a steady flow of charge.

📌 Key Points

▸
Current is measured in Amperes ( $A$ ).
▸
Resistance is measured in Ohms ( $\Omega$ ).
▸
Voltage is measured in Volts ( $V$ ).
▸
Ohm's Law applies to ohmic conductors at a constant temperature.

✅ Advantages

▸
Provides a simple linear relationship between electrical variables.

❌ Disadvantages / Limitations

▸
Does not apply to non-ohmic components like diodes or transistors where resistance changes with voltage.

🛠️ Applications / Uses

▸
Designing basic electronic circuits.
▸
Calculating power consumption in domestic appliances.

📄 Additional Information

▸
In this problem, $V = 20 \text{ V}$ and $R = 10 \text{ } \Omega$ .
▸
Option A ( $0.5 \text{ A}$ ) results from incorrectly calculating $\frac{10}{20}$ .
▸
Option C ( $200 \text{ A}$ ) results from incorrectly calculating $20 \times 10$ .
▸
Option D ( $1 \text{ A}$ ) results from incorrect arithmetic or interpretation of the values.

📊 Diagram / Illustration

✅

B is correct — Using Ohm's Law, $I = \frac{V}{R} = \frac{20 \text{ V}}{10 \text{ } \Omega} = 2 \text{ A}$ .

Core Concepts Used

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Ohm's Law Electrical Resistance Electric Current

💡 EXAM TIP

Always ensure units are in SI units (Volts, Ohms, Amperes) before plugging values into $I = \frac{V}{R}$ to avoid calculation errors.

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