Key relationship
Id=ε₀ dΦE/dt=ε₀A dE/dt; ∮B·dℓ=µ₀(Ic+Id).
Physics · Class 12
Displacement current
A charging capacitor carries conduction current in its wires and equal displacement current through its gap. No charge carriers need cross the dielectric gap.
Open the interactive experiment →Displacement current
தேக்கி இடைவெளியில் மாறும் மின்பாயம் இடப்பெயர்ச்சி மின்னோட்டத்தைத் தரும். மின்னூட்டத் துகள்கள் இடைவெளியைத் தாண்டத் தேவையில்லை.
Key notes, relationships and model limits
Remember
A charging capacitor carries conduction current in its wires and equal displacement current through its gap. No charge carriers need cross the dielectric gap.
Common trap
Displacement current accounts for changing electric flux; charge carriers do not cross the ideal capacitor’s insulating gap.
Model limits
Uniform circular-plate field with a concentric Ampere loop; the loop encloses full displacement current outside the plates and the corresponding area fraction inside. Negligible fringing.
What you will learn
Use the controls and plotted relation to explain displacement current.
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
For A=100 cm² and dE/dt=10¹⁰ V/(m s), Id≈0.000885 A.
Why this matters
The model connects displacement current with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
Displacement current in a charging capacitor gap comes from?
- Charge carriers crossing the insulating gap.
- Changing electric flux.
- A steady electric field with no change in flux.
Read the explanation
Changing electric flux.
Course connection: Class XII Chapter 8. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.