CBSE Guess > Papers > Important Questions > Class XII > 2011 > Physics > Physics By Mr. Ajay Sharma
CBSE CLASS XII
Moving Charge And Magnetism
(Q.1) What is the force between two straight conductors if they carry current in opposite direction? ( 1 mark )
(Q.2) Circular loop of a wire and a long straight wire carry currents Ic and Ie, respectively as shown in figure. Assuming that these are placed in the same plane, the magnetic fields will be zero at the centre of the loop when the separation H is :
(Q.3) A current carrying loop is placed in a uniform magnetic field. The torque acting on it, does not depend upon ( 1 mark )
(a) Shape of the loop
(b) Area of the loop
(c) Value of the current
(d) Magnetic field(Q.4) If a particle is moving in a uniform magnetic field then (H) ( 1 mark )
(a) its momentum changes but total energy remains the same
(b) both momentum and total energy remains the same
(c) its total energy changes but momentum remains same
(d) both momentum and total energy will change(Q.5) In cyclotron the charged particle may be accelerated upto energies ( 1 mark )
(a) Several eV
(b) MeV
(c) BeV
(d) Kev(Q.6) Four wires, each of length 2.0 m, are bent into four loops P, Q, R and S and then suspended in a uniform magnetic field. If the same current is passed in each, then the torque will be maximum on the loop (H)
( 1 mark )
(a) P
(b) Q
(c) R
(d) S(Q.7) A galvanometer can be converted into an ammeter by using ( 1 mark )
(a) Low resistance in series
(b) Low resistance in parallel
(c) High resistance in series
(d) High resistance in parallel(Q.8) A magnetic field is present, the direction of which is perpendicular to the plane of the paper from the top to bottom. An electron is projected into the field in the plane of paper with a constant velocity. Looking in the initial direction of motion of the electron, as it enters the magnetic field, it would ( 1 mark )
(a) Move perpendicular to the plane of the paper on a circular path upwards
(b) Move perpendicular to the plane of the paper on a circular path towards right
(c) Move in the plane of the paper on a circular path towards the left
(d) Move perpendicular to the plane of the paper on a circular path downwards.(Q.9) In a mass spectrograph, an ion x of mass number 24 and charge + e and another ion y of mass 22 and charge + 2e enter in a perpendicular magnetic field with the same velocity. The ratio for the radii of their circular path in the field will be (H) ( 1 mark )
(a) 24/11
(b) 11/24
(c) 22/11
(d) 11/22(Q.10) Two parallel wires are carrying electric currents of equal magnitude and in the same direction. They exert ( 1 mark )
(a) An attractive force on each other
(b) A repulsive force on each other
(c) No force on each other
(d) Magnetic force(Q.11) A positive charged particle is moving with velocity v enters into a region of space having a constant magnetic induction B. The particle will experience the largest deflection force when the angle between the vector A and B is ( 1 mark )
(a) 0°
(b) 45°
(c) 90°
(d) 180°(Q.12) A very long straight wire carries a current I. At the instant when a charge + Q at point P has velocity v , as shown, the force on the charge is (H) ( 1 mark )
(a) Along OY
(b) Opposite to OY
(c) Along OX
(d) Opposite to OX(Q.13) Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current. The force of attraction per unit length between the two wires is ( 1 mark )
(a) 2 × 10–7 N/m
(b) 2 × 10–8 N/m
(c) 5 × 10–8 N/m
(d) 10–7 N/m(Q.14) Two circular, similar, coaxial loops carry equal current in the same direction as shown in figure. If the loops are brought nearer, what will happen? (H)
( 1 mark )
(a) Current will increase in each loop
(b) Current will decrease in each loop
(c) Current will remain same in each loop
(d) Current will increase in one and decrease in the other(Q.15) A charge particle enters a magnetic field at an angle of 45° with the magnetic field. The path of the particle will be ( 1 mark )
(a) Helical
(b) An ellipse
(c) A circle
(d) A straight line(Q.16) An infinite long straight conductor is bent in the shape shown in fig. It carries a current i amp and the radius of circular loop is r meter. Then the magnetic induction at the centre of the circular loop will be (H)
(d) same as that of the infinite long straight conductor(Q.17) A direct current flows through a solenoid, entering in an anticlockwise sense at the end A. This solenoid, made to float on still water will
(a) Have the end A point towards north
(b) Have the end A point towards south
(c) Stay in any point towards south
(d) Move in a straight line with constant velocity ( 1 mark )(Q.18) A solenoid of 1.5 metre length and 4.0 cm diameter possesses 10 turns per cm. A current of 5 ampere is flowing through it. The magnetic field at the axis inside the solenoid is : (H)
(Q.19) The work done by a magnetic field, on a moving charge is ( 1 mark )
(a) Zero because acts parallel to q
(b) Positive because acts perpendicular to q
(c) Zero because acts perpendicular to q
(d) Negative because acts parallel to q(Q.20) A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. This particle will ( 1 mark )
(a) Get deflected in vertically upward direction
(b) Move in circular path with an increased speed
(c) Move in a circular path with decreased speed
(d) Move in a circular path with uniform speed(Q.21) If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be ( 1 mark )
(a) Only inside the pipe
(b) Only outside the pipe
(c) Neither inside nor outside the pipe
(d) Both inside and outside the pipe(Q.22) A proton of mass 1.67 × 10–27 kg and charge 1.6 × 10–19 C is projected with a speed of 2 × 106ms–1 at an angle of 60º to the X-axis. If a uniform magnetic field of 0.104 tesla is applied along Y-axis, the path of proton is (H) ( 1 mark )
(a) A circle of radius = 0.2 m and time period = 2p × 10–7 s
(b) A circle of radius = 0.1 m and time period = 2p × 10–7 s
(c) A helix of radius = 0.1 m and time period = 2p × 10–7 s
(d) A helix of radius = 0.2 m and time period = 2p × 10–7 s(Q.23) A length of wire carries a steady current. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is (1mark )
(a) Quarter of its first value
(b) Unaltered
(c) Four times of its first value
(d) Half of its first value(Q.24) Which of the following graphs, shows the variation of magnetic induction B with distance r from a long wire carrying a current? (H) ( 1 mark )
(a)
(b)
(c)
(d)
(Q.25) A cell is connected between two points of a uniformly thick circular conductor. i1 and i2 are the currents flowing in two parts of the circular conductor of radius a. The magnetic field at the centre of the loop will be (H) ( 1 mark )
(Q.26) What is the resistance of an ideal ammeter? ( 1 mark ) (Q.27) Name the force
which is experienced by the moving charged particles in the magnetic field. (1 mark )
(Q.28) When will be the force experienced by a moving charge in a magnetic field maximum? ( 1 mark )
(Q.29) What happens to the speed and kinetic energy of a particle when it is projected perpendicular to the magnetic field. ( 1 mark )
(Q.30) How ammeter and voltmeter is connected in a circuit? ( 1 mark )
(Q.31) Which will experience greater torque? A circular loop or a square loop having same current and placed in a uniform magnetic field. (H) ( 1 mark )
(Q.32) On what principle does cyclotron works? ( 1 mark )
(Q.33) Astraight wire of mass 200 g and length 4.9 m carries a current of 2 A. It is suspended in mid(H) ( 1 mark )
(a) 0.3
(b) 0.2
(c) 2
(d) 0.4(Q.34) Circular loop of a wire and a long straight wire carry currents Icand Ie, respectively as shown in figure. Assuming that these are placed in the same plane, the magnetic fields will be zero at the centre of the loop when the separation H is : (H) ( 1 mark )
(Q.35) What is the conductance of a conductor of resistance 5 milli ohm? (H) ( 1 mark )
(a) 200 mho
(b) 100 mho
(c) 500 mho
(d) 300 mho(Q.36) A short bar magnet is placed with its north pole pointing south. Theneutral point is 10 cm away from the center of the magnet. If H=0.4 gauss, what is the magnetic moment of the magnet. (H) ( 1 mark )
(a) 0.2 A m2
(b) 2 A m2
(c) 20 A m2
(d) 0.02 A m2(Q.37) Define Biot-Savart Law. ( 2 Marks )
(Q.38) What is magnetic effect of current? ( 2 Marks )
(Q.39) A galvanometer has a resistance of 55 ohms. It gives full-scale deflection by a current of 10 milliamperes. What resistance must be connected across it to enable it to read 1 ampere? ( 2 Marks )
(Q.40) What is the force on a charged particles when it is moving at right angle to the applied magnetic field? ( 2 Marks )
(Q.41) What is the force between two parallel conductors carrying current? (2 Marks )
(Q.42) Why a galvanometer cannot be used as an ammeter directly? ( 2 Marks )
(Q.43) What is the magnitude of magnetic field at a distance R-from a long straight wire carrying a current I? ( 2 Marks )
(Q.44) Define Lorentz force? ( 3 Marks )
(Q.45) Define Ampere’s circuital law? ( 3 Marks )
(Q.46) What is cyclotron frequency? ( 3 Marks )
(Q.47) Two straight wires A and B of length 20 m and 32 m and carrying currents 4 A and 5 A respectively in same directions, are parallel to each other 4 m apart.Find the force on the 10 m long section of the wire B near its centre. (H)(3Marks )
(Q.48) A straight conducting rod of length .06m and mass 30g is suspended by two vertical wires at its ends. A current of 1 A is set up in the rod. Find
(a) what magnetic field should be set up normal to the conductor so that tension in the wire is zero?
(b) what will be the total tension in the wire if the direction of the current is reversed (H) ( 5 Marks )(Q.49) A very long wire carrying a current i=10 A is bent at right angles.Find the magnetic induction at a point lying on a perpendicular to the wires drawn through the point of bending, at a distance l= 30 cm from it. ( 5 Marks )
(Q.50) In an ammeter, 0.5% of main current pass through galvanometer. If resistance of galvanometer is G, what will be the resistance of ammeter? (H) ( 5 Marks )
(Q.51) The plane of a rectangular loop of wire of sides 0.05m and 0.08m is placed in a uniform magnetic field of induction 1.5 x 10-2 texla. A current of 10.0 amp flows through the loop. The plane of the coils are normal to the lines of induction. what is the torque acting on it? (H) ( 5 Marks )
(Q.52) Derive the formula for magnetic field on the axis of a circular current loop? ( 5 Marks )
(Q.53) Mention the principle and construction of moving coil galvanometer? ( 5 Marks )
(Q.54) Differentiate between a solenoid and a toroid.
Submitted By Mr. Ajay Sharma
Email Id : [email protected]
