Torque on a rectangular current loop in a uniform Bएकसमान B में आयताकार धारा पाश पर बल आघूर्णTorque on a rectangular current loop in a uniform B

NCERT Fig 4.18–4.19 · Class 12 Physics · Chapter 4 · interactive diagram

Parts and what they mean

• Uniform field B (to the right) (एकसमान क्षेत्र B (दाईं ओर)) — Lies in the plane of the loop in (a).
• Rectangular loop ABCD, current I (आयताकार पाश ABCD, धारा I) — AB, CD have length b (⊥ B); BC, DA have length a (∥ B) → no force on BC, DA.
• F₁ on AB: into the page (AB पर F₁: पृष्ठ के अंदर) — F₁ = I b B. Current up × B right = into the page.
• F₂ on CD: out of the page (CD पर F₂: पृष्ठ से बाहर) — Equal and opposite to F₁: net force zero, but they form a couple.
• Magnetic moment m = IA (into the page) (चुंबकीय आघूर्ण m = IA (पृष्ठ के अंदर)) — Current is clockwise as seen → by the thumb rule A (and m) point into the page.
• Loop seen from above (edge-on) (ऊपर से दिखता पाश (किनारे से)) — AB at one end, CD at the other.
• m at angle θ to B (B से कोण θ पर m) — The couple turns m towards B.
• F₁ (on AB) (F₁ (AB पर)) — Still I b B, same direction as before.
• F₂ (on CD) (F₂ (CD पर)) — Opposite to F₁.
• Arm of the couple = a sin θ (बल-युग्म की भुजा = a sin θ) — τ = I b B × a sin θ = IAB sin θ. Zero at θ = 0° (stable) and 180° (unstable).

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 4.18–4.19. Report a mistake