Define electric current
Scenario
Nadi mein paani ka flow fast ya slow ho sakta hai.
Waise hi wire mein electric charge ke flow ko hum kya kehte hain?
Mental model
Electric current wire ke andar electrons ki nadi (river) jaisa hai.
Jaise paani ka flow water current hota hai, waise hi electric charges ka flow electric current hota hai. Jitne zyada charges ek second mein guzrenge, current utna hi zyada hoga.
Explanation
Electric current ka matlab hai rate of flow of electric charges. Kisi conductor, jaise copper wire, ke andar negative charges (electrons) ek direction mein bhagte hain.
Mathematical terms mein, electric current ko `I` se denote karte hain. Iska formula `I = Q / t` hota hai, jahan `Q` total charge hai aur `t` time hai.
Electric charge (`Q`) ki unit `Coulomb` (`C`) hoti hai aur time (`t`) ki unit `second` (`s`) hoti hai. Isliye, current ki SI unit `Ampere` (`A`) hai. Ek `Ampere` ka matlab hai ki `1 Coulomb` ka charge kisi cross-section se `1 second` mein flow kar raha hai.
Chhoti currents ko measure karne ke liye `milliampere` (`mA`) ya `microampere` (`uA`) ka use hota hai. Current ko measure karne wale device ko ammeter kehte hain, jise hamesha series mein connect kiya jata hai.
Worked example
Problem: A current of `0.5 A` is drawn by a filament of an electric bulb for `10 minutes`. Find the amount of electric charge that flows through the circuit.
- Pehle time ko seconds mein convert karte hain.
- Current aur time diya hai, charge `Q` nikalna hai.
- Formula `Q = I * t` use karte hain.
- Multiply karke charge find karte hain.
Answer: 300 C
Problem: If `120 C` of charge passes through a wire in `1 minute`, calculate the electric current.
- Time ko seconds mein badalte hain.
- Current ka formula `I = Q/t` use karte hain.
- Divide karke answer nikalte hain.
Answer: 2 A
Key points
- Formula: `I = Q / t` (Current = Charge / Time).
- SI Unit: The SI unit of current is `Ampere` (`A`).
Common mistakes
- Not converting time to seconds: `I = Q/t` formula mein time ko hamesha seconds mein rakho. Agar `1 minute` diya hai, toh usko `60 seconds` mein convert karna mat bhoolna.
Recall questions
- What is the SI unit of electric charge?
- Which instrument measures electric current?
- What is electric current?
Questions & answers
What does an electric circuit mean?
A continuous and closed path of an electric current is called an electric circuit.
Approach: Define circuit as a closed loop for current to flow.
A current of 0.5 A is drawn by a filament for 10 minutes. Find the amount of electric charge.
300 C
Approach: Q = I × t = 0.5 A × 600 s = 300 C.
Continue learning
Next: Define electric potential difference
Next: State Ohm's Law