State Ohm's Law
Scenario
Agar aap pipe mein paani ka pressure badhate hain, toh paani aur zyada tezi se flow karta hai.
Kya wire mein bhi voltage badhane se current badh jata hai?
Mental model
Voltage aur current ek dusre ke direct friends hain. Ek badhega, toh dusra bhi badhega.
Ohm's Law kahta hai ki agar rukaawat (resistance) fix rahe, toh circuit mein jitna zyada voltage (dhakka) lagaoge, utna hi zyada current (flow) bahar aayega.
Explanation
German physicist Georg Simon Ohm ne `1827` mein current (`I`) aur potential difference (`V`) ke beech ka relation dhunda tha.
Ohm's law state karta hai: The potential difference (`V`) across the ends of a given metallic wire in an electric circuit is directly proportional to the current (`I`) flowing through it, provided its temperature remains the same. Mathematical form mein, `V ∝ I`.
Is proportionality ko hatane ke liye hum ek constant use karte hain jise Resistance (`R`) kehte hain. Toh formula banta hai `V = I * R`.
Yeh `V-I` graph hamesha origin se start hoti ek straight line hoti hai (constant temperature par). Yeh line is baat ka saboot hai ki voltage badhane se current utne hi proportion mein badhta hai.
Worked example
Problem: State Ohm's Law and write its mathematical expression.
- Law ka definition likhna hota hai constant temperature mention karke.
- Constant of proportionality `R` ka use karke equation banate hain.
Answer: `V = IR`
Problem: What is the nature of the graph between `V` and `I` for an ohmic conductor?
- Kyunki `V` aur `I` directly proportional hain, graph linear hota hai.
- Straight line jo `(0,0)` se start hoti hai.
Answer: A straight line passing through the origin.
Key points
- Statement: `V` is directly proportional to `I` at a constant temperature.
- Mathematical Form: `V = IR`, where `R` is the constant resistance.
Common mistakes
- Forgetting the 'constant temperature' condition: Ohm's Law sirf tabhi kaam karta hai jab temperature same ho, kyunki garmi se wire ka resistance badal jata hai.
Recall questions
- What is the constant of proportionality in Ohm's Law called?
- What is the shape of the `V-I` graph for a metallic wire?
- What does Ohm's law state?
Questions & answers
State Ohm's law.
Potential difference across a conductor is directly proportional to the current, provided temperature remains constant.
Approach: Write the exact statement.
Why does Ohm's law fail if the temperature of the conductor changes?
Because a change in temperature changes the resistance of the material.
Approach: Highlight that Ohm's law assumes constant physical conditions like temperature.
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