A resistor has a potential difference of 12 V and a current of... | General Science MCQ | Examoogle

General SciencePhysics: Electricity

A resistor has a potential difference of 12 V and a current of 3 A flowing through it. What is the resistance of the resistor?

36 ohms

4 ohms

9 ohms

0.25 ohms

Correct Answer

⚙️ TE • Technical Concept & PrincipleGeneral SciencePhysics: Electricity

Option B

4 ohms

Quick Summary:

The resistance of a conductor is determined by Ohm's Law, which states that the current flowing through a conductor is directly proportional to the potential difference across its ends, provided temperature remains constant. By rearranging the formula $V = IR$ , we find the resistance as $R = \frac{V}{I} = \frac{12 \text{ V}}{3 \text{ A}} = 4 \, \Omega$ .

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of voltage as the pressure of water in a pipe, current as the rate of water flow, and resistance as the narrowing of the pipe; a narrower pipe (higher resistance) restricts the flow even if the pressure is constant.

🧠 Memory Mnemonic / Shortcut Aid

VIR (as in 'V' is for 'I' times 'R')

🔢 Key Formulas

$V = I \times R$ — Ohm's Law relationship

$R = \frac{V}{I}$ — Calculation of resistance from voltage and current

⚙️ Working Principle

Ohm's Law describes the relationship between voltage ( $V$ ), current ( $I$ ), and resistance ( $R$ ). Resistance is the measure of opposition to the flow of electric current in a circuit. When a potential difference of $12 \text{ V}$ is applied across a resistor, it forces charge carriers to move against the material's inherent resistance, resulting in a current flow of $3 \text{ A}$ .

📌 Key Points

▸
The SI unit of resistance is the Ohm ( $\Omega$ ).
▸
Ohm's Law holds true only for ohmic conductors where resistance remains constant.
▸
Potential difference is measured in Volts (V) and current in Amperes (A).

✅ Advantages

▸
Allows for precise determination of circuit components.
▸
Fundamental for calculating power consumption in electrical devices.

❌ Disadvantages / Limitations

▸
Not applicable to non-ohmic devices like diodes or transistors where resistance changes with voltage.

🛠️ Applications / Uses

▸
Design of electronic circuits
▸
Measuring the resistivity of materials

📄 Additional Information

▸
The standard unit of resistance, the Ohm ( $\Omega$ ), is named after Georg Simon Ohm.
▸
Option A (36 ohms) is the result of multiplying voltage and current ( $12 \times 3$ ).
▸
Option C (9 ohms) is the result of subtracting current from voltage ( $12 - 3$ ).
▸
Option D (0.25 ohms) is the reciprocal calculation ( $\frac{3}{12}$ ).

📊 Diagram / Illustration

✅

B is correct — Using Ohm's Law, $R = \frac{12 \text{ V}}{3 \text{ A}} = 4 \, \Omega$ .

Core Concepts Used

Click any tag to open in AI Tutor

Ohm's Law Electrical Resistance Potential Difference

💡 EXAM TIP

Always verify units before calculation; if current was in mA, convert it to A first to keep the result in standard Ohms.

Was this solution helpful?

Discussion (0)

Loading discussion...

Prev Next

Correct Answer

Related Questions

Discussion (0)