Define electric potential difference
Scenario
Agar pipe seedha zameen par pada ho toh paani khud nahi behta. Uske pichhe pressure chahiye hota hai.
Wire mein electrons ko dhakka (pressure) kaun deta hai?
Mental model
Potential difference wahi electrical pressure (dhakka) hai jo charge ko aage badhata hai.
Bina potential difference (voltage) ke, charges flow nahi karte. Battery ya cell ek pressure difference create karta hai taaki electrons wire ke andar ek point se doosre point tak flow kar sakein.
Explanation
Physics mein, electric potential difference (jise voltage bhi kehte hain) ko us work done ke roop mein define kiya jata hai, jo ek unit charge ko ek point se doosre point tak le jaane mein lagta hai.
Iska formula `V = W / Q` hota hai, jahan `V` potential difference hai, `W` kiya gaya work (`Joules` mein) hai, aur `Q` charge (`Coulombs` mein) hai.
Iska SI unit `Volt` (`V`) hai, jo Italian physicist Alessandro Volta ke naam par rakha gaya hai. `1 Volt` ka matlab hai ki `1 Coulomb` charge ko move karne ke liye `1 Joule` work karna pada.
Potential difference ko naapne ke liye hum voltmeter ka istemaal karte hain. Voltmeter ko hamesha un do points ke beech parallel mein connect kiya jata hai jinke beech ka voltage check karna ho.
Worked example
Problem: How much work is done in moving a charge of `2 C` across two points having a potential difference `12 V`?
- Charge aur voltage ki values note karte hain.
- Formula `V = W / Q` ko rearrange karte hain.
- Values put karke multiply karte hain.
- Work nikal lete hain, jiski unit `Joule` hoti hai.
Answer: 24 J
Problem: A work of `100 J` is done to move a `5 C` charge between two points. Find the potential difference.
- Work (`W`) aur Charge (`Q`) diya gaya hai.
- Potential difference ka formula use karte hain.
- Values daal kar divide karte hain.
Answer: 20 V
Key points
- Formula: `V = W / Q` (Voltage = Work / Charge).
- Voltmeter connection: Always connected in parallel across the points to be measured.
Common mistakes
- Connecting voltmeter in series: Voltmeter ka resistance bohot zyada hota hai, isliye ise series mein lagane se current block ho jata hai. Hamesha ise parallel mein connect karein.
Recall questions
- What is the SI unit of potential difference?
- Name the device used to measure potential difference.
- What is potential difference?
Questions & answers
Name a device that helps to maintain a potential difference across a conductor.
A battery or a cell.
Approach: Think of what provides the 'push' for the current.
How much work is done in moving a charge of 2 C across two points having a potential difference 12 V?
24 J
Approach: W = V × Q = 12 V × 2 C = 24 J.
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