Tiêu đề NT 16 PAPER.pdf ✅

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11. The meter-bridge wire AB shown in figure is 50 cm long. When AD = 30 cm, no deflection occurs in the galvanometer. Find R. (A) 1  (B) 2  (C) 3  (D) 4  12. The potential gradient of a potentiometer wire is defined as (A) the fall of potential per unit length (B) the fall of potential per unit area (C) the fall in potential across the ends of wires (D) None of the above 13. A thin wire is bent to form a square loop ABCD. A battery of e.m.f 2V is connected between the points A and C. The magnetic induction due to the current in the loop at centre O will - (A) be zero (B) point away from the plane of paper (C) point along the plane of paper (D) point into the plane of paper 14. The magnetic field on the axis of a current carrying circular coil of radius a at a distance 2a from its centre will be- (A) 0 i 2  (B) 0 i 10 5a  (C) 0 i 4a  (D) 0i 15. The velocities of two identical charged particles entering a uniform magnetic field are in the ratio 1 : 3. Their path becomes circular in the magnetic field. The ratio of radii of their circular paths will be- (A) 1 : 3 (B) 3 : 1 (C) 1 : 9 (D) 9 : 1 16. A charged particle with charge q is moving in a uniform magnetic field. If this particle makes any angle with the magnetic field then its path will be - (  0o,90°, 180o) (A) circular (B) straight line (C) helical (D) parabolic 17. When a current of 1 ampere is passed in a coil lying in the magnetic meridian then a magnetic needle at its centre gives some deflection. If the current in the coil is increased to 8 ampere then at what distance from the centre of the coil will the deflection of needle remains unchanged ? (A) 2R (B) 4R (C) 8R (D) R 18. How does the magnetic susceptibility of a paramagnetic material change with absolute temperatue T ? (A)  T (B)  T –1 (C) = constant (D)  e T 19. Lenz’s law is based on the law of conservation of – (A) charge (B) momentum (C) mass (D) energy 20. A semicircular wire of radius R is rotated with constant angular velocity  about an axis passing through one end and perpendicular to the plane of the wire. There is a uniform magnetic field of strength B. The induced e.m.f. between the ends is: (A) B R 2 /2 (B) 2 B R 2 (C) is variable (D) none of these 21. An AC voltage of V = 220 2 sin 100 t 2       +   is applied across a DC voltmeter, its reading will be: (A) 220 2 V (B) 2 V (C) 220 V (D) zero C A B D
22. Displacement current flows in (A) resistance only (B) Capacitor only (C) Inductor only (D) All of these 23. If in a region there is a time varying electric field then which of the following Maxwell’s Equation will be most suitable ? (A) E 0 d B.dl dt → →  = +   I (B) B.dl 0 → → =   I (C) E 0 0 d B.dl dt → →    =  +       I (D) B 0 0 d B.dl dt → →    =  +       I 24. The correct I–H curve for paramagnetic materials is :- (A) (B) (C) (D) 25. The area of B–H loop for soft iron, as compared to that for steel is :- (A) More (B) Less (C) Equal (D) None of the above 26. A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It: (A) will stay in north-south direction only (B) will stay in east-west direction only (C) will become rigid showing no movement (D) will stay in any position 27. A magnetic needle suspended parallel to a magnetic field requires 3 J of work to turn it through 60°. The torque needed to maintain the needle in this position will be : (A) 3 J (B) 3 2 J (C) 2 3 J (D) 3J 28. Tesla is a unit of - (A) magnetic flux (B) magnetic flux density (C) electric flux (D) self inductance 29. Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon : (A) the rates at which currents are changing in the two coils (B) relative position and orientation of the two coils (C) the materials of the wires of the coils (D) the currents in the two coils 30. If the length and area of cross-section of an inductor remain same but the number of turns is doubled, its self-inductance will become - (A) Half (B) Four times (C) Double (D) One-fourth 31. In the circuit shown, X is joined to Y for a long time, and then X is joined to Z. The total heat produced in R2 is : (A) 2 2 1 LE 2R (B) 2 2 2 LE 2R (C) 2 1 2 LE 2R R (D) 2 2 2 1 LE R 2R H I H I H I H I