Axial field of a finite solenoidपरिमित परिनालिका का अक्षीय क्षेत्रAxial field of a finite solenoid

NCERT Fig 5.3(a) · Class 12 Physics · Chapter 5 · interactive diagram

Parts and what they mean

• Solenoid (परिनालिका) — n turns per unit length, each carrying current I. Its magnetic moment is m = n(2l)·I·πa² (total turns × I × area).
• Axis of the solenoid (परिनालिका का अक्ष) — The line through the centre O along which we find B.
• Centre O (केंद्र O) — Distances r and x are measured from here.
• A thin slice dx (पतला भाग dx) — Contains n·dx circular turns — a small current loop. Adding the axial fields of all such slices gives B at P.
• Position x of the slice (भाग की स्थिति x) — Distance of the slice from O; it runs from −l to +l.
• Point P on the axis (अक्ष पर बिंदु P) — Far away (r ≫ l and r ≫ a).
• Field at P (P पर क्षेत्र) — B = (μ₀/4π)(2m/r³) along the axis — exactly the far axial field of a bar magnet of moment m (Eq. 5.1).
• Distance r (दूरी r) — From the centre O to P.
• Length 2l (लंबाई 2l) — Total length of the solenoid.
• Radius a (त्रिज्या a) — Radius of each turn.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 5.3(a). Report a mistake