This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
ScanSolve AI Answer
None of the three situations result in motional emf. Step 1: Situation (a) – A positively charged dry cloth is rubbed on a piece of paper which is cut into the shape of a loop. Rubbing produces static electric charge via friction (triboelectric effect). Placing the charged cloth near the paper loop causes electrostatic induction: opposite charges separate on the loop. No magnetic field is present. No conductor motion in a magnetic field. No change in magnetic flux. No motional emf ( = 0). Step 2: Situation (b) – A charged loop is placed in a uniform magnetic field (into the page). The loop is stationary. Magnetic field is static and uniform. Magnetic flux _B = B · A 0^ = B A is constant (no motion, no change in B). Faraday's law: induced emf = -(d_B)/(dt) = 0. Charge on loop does not produce emf. No velocity v. No motional emf ( = 0). Step 3: Situation (c) – The page (loop) on which writing is done is moving towards north. Earth's magnetic field: horizontal component B_h ≈ 0.3–0.4 gauss towards magnetic north; vertical component B_v downward. Field approximately uniform over small loop. Loop translates with velocity v towards north (parallel to B_h). For translational motion of rigid loop in uniform B, magnetic flux _B constant (area and B_ unchanged). Motional emf = (v × B) · dl = 0 (closed path, conservative field). No motional emf ( = 0). None