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General SciencePrevious Year Paper 2024

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What is the relationship between current (I), power (P), and voltage (V)?

I = P2V

I = PV

I = V ÷ P

I = P ÷ V

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral SciencePrevious Year Paper 2024

Option D

I = P ÷ V

Quick Summary:

Electric power ( $P$ ) is defined as the rate at which electrical energy is transferred or consumed per unit time in an electric circuit. Mathematically, power is the product of voltage ( $V$ ) and current ( $I$ ), expressed as $P = V \times I$ . Rearranging this fundamental relation to solve for current gives $I = \frac{P}{V}$ or $I = P \div V$ .

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🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of electrical power as the total water flow rate delivered by a pipe system. Voltage is like water pressure pushing through the pipe, while current is the volume of water flowing per second. To find how much water is flowing (current), you divide the total flow rate (power) by the pressure (voltage).

🧠 Memory Mnemonic / Shortcut Aid

P-V-IPower Triangle: Place P at the top, and V and I at the bottom. To find Current (I), cover 'I' to see P over V ( $I = P \div V$ ).

🔢 Key Formulas

$P = V \times I$ — Electric Power in terms of Voltage and Current

$I = \frac{P}{V}$ — Current in terms of Power and Voltage

$V = \frac{P}{I}$ — Voltage in terms of Power and Current

$P = I^2 R = \frac{V^2}{R}$ — Power combined with Ohm's Law ( $V = I \times R$ )

⚙️ Working Principle

When an electric potential difference (voltage $V$ ) causes a charge flow (current $I$ ) across a circuit component, work is done per unit time. Electric power is given by $P = \frac{W}{t} = \frac{V \times Q}{t}$ . Since current is $I = \frac{Q}{t}$ , substituting gives $P = V \times I$ . By algebraic transposition, dividing power by voltage yields the current passing through the load.

📌 Key Points

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Electric power is measured in Watts ( $W$ ), where $1\text{ W} = 1\text{ Joule/second}$ .
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Voltage ( $V$ ) is electrical potential difference measured in Volts ( $V$ ).
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Electric current ( $I$ ) is the rate of flow of electric charge measured in Amperes ( $A$ ).
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For a fixed power rating, current is inversely proportional to voltage ( $I \propto \frac{1}{V}$ ).

🛠️ Applications / Uses

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Calculating the fuse rating required for household electric appliances (e.g., $I = \frac{P}{V}$ ).
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High-voltage electrical power transmission to reduce current and lower $I^2 R$ heat losses.

📄 Additional Information

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1 Watt is equal to 1 Volt multiplied by 1 Ampere ( $1\text{ W} = 1\text{ V} \times 1\text{ A}$ ).
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Option A ( $I = P^2 V$ ) is mathematically incorrect as power is squared.
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Option B ( $I = PV$ ) incorrectly multiplies power and voltage instead of dividing.
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Option C ( $I = V \div P$ ) is the inverse formula, which actually represents $\frac{1}{I}$ .

📊 Diagram / Illustration

✅

D is correct — Electric power is given by $P = V \times I$ , which rearranges algebraically to $I = P \div V$ .

Core Concepts Used

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Electric Power Ohm's Law Electric Current Potential Difference

💡 EXAM TIP

In competitive exams, remember that electrical transmission lines transmit power at high voltage ( $V$ ) to minimize current ( $I$ ), which drastically reduces line loss ( $P_{\text{loss}} = I^2 R$ ).

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