Physics-DPP-2-Magnetism

PHYSICS Topic: Magnetism Date: 1. A flat circular coil of n turns and radius r carries a current i. Its magnetic moment is: (a) r2 ni (b) 2rni (c) μ æç ni ö÷ (d)  r2ni 0 çè 2πr ø÷ 0 2. A long straight conductor carrying a current lies along the axis of a ring. The conductor will exert a force on the ring if the ring. (a) carries a current (b) has uniformly distributed charge (c) has nonuniformly distributed charge (d) none of the above 3. Two straight infinitely long current carrying wires are kept along 2-axis at the co-ordinates [0, a, 0] & [0, – a, 0] respectively as shown in figure. The current in each wire is equal & along negative z-axis (into the lane of the paper]. The variation of magnetic field on the x-axis will be approximately. (a) (c) (d) 4. A conductor ABCDEF, with each side of length L, is bent as shown. It is carrying a current I in a uniform magnetic induction (field) B, parallel to the positive y-direction. The force experienced by the wire is (a) BIL in the positive y-direction (b) BIL in the negative z-direction (c) 3BIL (d) zero 5. A horizontal straight conductor of mass m and length l is placed in a uniform verticle magnetic field of magnitude B. An amount of charge Q passes through the rod in a very short time such that the conductor begins to move only after all the charge has passed through it. Its initial velocity will be (a) BQlm (b) BQ lm (c) BQl Bl m (d) mQ PHYSICS Topic: Magnetism Date: 6. A conductor AB of length l, carrying a current i, is placed perpendicular to a long straight conductor XY carrying a current I, as shown. The force on AB will act (a) upward (b) downward (c) to the right (d) to the left 7. In the previous question, the force on AB has magnitude (a) 8. μ0 Ii In2 2π (b) (b) μ0 Ii In3 2π (c) (c) 3μ0 Ii 2π (d) (d) 2 μ0 Ii 3π A square loop ABCD, carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I. (a) There is no net force on the loop. (b) The loop will be attracted by the conductor only if the current in the loop flows clockwise. (c) The loop will be attracted by the conductor only if the current in the loop flows anticlockwise. (d) The loop will always be attracted by the conductor. 9. A flat coil of n turns, area A and carrying a current i is placed in a uniform magnetic field of magnitude B. The plane of the coil makes an angle  with the direction of the field. The torque acting on the coil is nAi (a) BinAsin (b) B sin θ (c) BinAcos  (d) Bin2 Acos 10. The square loop ABCD, carrying a current I, is placed in a uniform magnetic field B, as shown. The loop can rotate about the axis XX. The plane of the loop makes an angle  ( < 90º) with the direction of B. Through what angle will the loop rotate by itself before the torque on it becomes zero? (a)  (b) 90º –  (c) 90º +  (d) 180º –  PHYSICS Topic: Magnetism Answer Key Date: 1. (a) 2. (d) 3. (d) 4. (b) 5. (c) 6. (a) 7. (b) 8. (b) 9. (c) 10. (c)

Comments

Post a Comment

Popular posts from this blog

PHYSICS-15-10- 11th (PQRS) SOLUTION

XI (PQRS) PHYSICS REVIEW TEST-5 Select the correct alternative. (Only one is correct) [15 × 3 = 45] There is NEGATIVE marking. 1 mark will be deducted for each wrong answer. Q.31 Two trains, which are moving along different tracks in opposite directions towards each other, are put on the same track due to a mistake. Their drivers, on noticing the mistake, start slowing down the trains when the trains are 300 m apart. Graphs given below show their velocities as function of time as the trains slow down. The separation between the trains when both have stopped, is: (A) 120 m (B) 280 m (C) 60 m (D*) 20 m 1 [Sol: x1 = 2 1 × 10 × 40 = 200 m; x2 = – 2 × 8 × 20 = –80 m  xreletive = x1 + x2 = 280  separation = 300 – 280 = 20 m (D) ] Q.32 One end of a thin uniform rod of length L and mass M is riveted to the centre of a uniform circular disc of radius r and mass 2 M so that the rod is normal to the disc. The centre of mass of the combination from the centre of the disc is at dist
Read more

8-Circular Motion

8.1 (D) The maximum angular speed of the hoop corresponds to the situation when the bead is just about to slide upwards. The free body diagram of the bead is For the bead not to slide upwards. m2 (r sin 45°) cos 45° – mg sin 45° < N (1) where N = mg cos 45° + m2 (r sin 45º) sin 45° (2) From 1 and 2 we get.  = rad / s. 8.2 (C) Let v be the speed of particle at B, just when it is about to loose contact. From application of Newton's second law to the particle normal to the spherical surface. mv2 = mg sin  (1) r Applying conservation of energy as the block moves from A to B.. 1 mv2 = mg (r cos  – r sin ) (2) 2 Solving 1 and 2 we get 3 sin  = 2 cos  8.3 (A) As the mass is at the verge of slipping ∴ mg sin37 –  mg cos37 = m2r 6 – 8 = 4.5   = 3 16 8.4 (B) As when they collide vt  1  72v 2  2 2  25R   R = vt  t =   5R 6v Now angle covered by A =   vt R 11 Put t  angle covered by A = 6 8.5 (C) The acceleration vector s
Read more

4. THEORY-Current Electrictricity

CURRENT ELECTRICITY  1 . ELECTRIC CURRENT (a) Time rate of flow of charge through a cross sectional area is called Current. if q charge flows in time interval t then average current is given by q Iav = t and Instantaneous current i =. lim q  dq t0 t dt (b) Direction of current is along the direction of flow of positive charge or opposite to the direction of flow of negative charge. But the current is a scalar quantity. i i q+ velocity q– velocity SI unit of current is ampere and 1 Ampere = 1 coloumb/sec 1 coloumb/sec = 1A 2 . CONDUCTOR In some materials, the outer electrons of each atom or molecule are only weakly bound to it. These electrons are almost free to move throughout the body of the material and are called free electrons. They are also known as conduction electrons. When such a material is placed in an electric field, the free electrons drift in a direction opposite to the field. Such materials are called conductors. 3 . INSULATOR Another class o
Read more