Key relationship
∮B⃗·dℓ⃗=µ₀Ienc; Bsolenoid=µ₀NI/ℓ.
Physics · Class 12
Ampere wire and solenoid
Switch between a long wire and long solenoid. Ampere law yields an inverse-radius field around a wire and an approximately uniform interior field in a long solenoid.
Open the interactive experiment →Ampere wire and solenoid
ஆம்பியர் விதி மூலம் நீண்ட கம்பி மற்றும் நீண்ட சுருளின் புலம் பெறலாம். சுருளின் உள்ள்புலம் ஏறத்தாழ சீரானது.
Key notes, relationships and model limits
Remember
Switch between a long wire and long solenoid. Ampere law yields an inverse-radius field around a wire and an approximately uniform interior field in a long solenoid.
Common trap
The long-solenoid approximation applies away from its ends. A uniform interior result does not describe the end field.
Model limits
Infinite wire, long ideal solenoid away from ends; for coil selection the line-integral readout is only a Bℓ comparison, not an Ampere contour.
What you will learn
Use the controls and plotted relation to explain ampere wire and solenoid.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
N=100, I=2 A, ℓ=0.5 m gives B≈0.503 mT.
Why this matters
The model connects ampere wire and solenoid with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
For fixed N and I, doubling solenoid length gives B?
- Twice the original field.
- Half the original interior field.
- The same field because turns are fixed.
Read the explanation
Half the original interior field.
Course connection: Class XII Chapter 4. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.