Match the column
moving-charges-and-magnetism-class12-mcq-1.png
  • p -> ii, q -> ii, r -> i, s -> ii
  • p -> ii, q -> i, r -> i, s -> ii
  • p -> ii, q -> ii, r -> ii, s -> i
  • p -> ii, q -> ii, r -> i, s -> i
Match the column
moving-charges-and-magnetism-class12-mcq-2.png
  • p -> iii, q -> ii, r -> iv, s -> i
  • p -> ii, q -> iii, r -> iv, s -> i
  • p -> iv, q -> iii, r -> ii, s -> i
  • p -> iv, q -> ii, r -> iii, s -> i
The resistance of an ideal voltmeter is
  • zero
  • 1000 Ω
  • 5000 Ω
  • infinity
In a cyclotron, a charged particle
  • undergoes acceleration all the time
  • speeds up in a dee.
  • slows down within a dee and speeds up between dees.
  • speeds up between the dees because of the magnetic field
Two wires carrying
  • Antiparallel current attract each other
  • Antiparallel current repel each other.
  • Equal magnitudes of antiparallel current attract each other.
  • Parallel current repel each other.
A positive charge is moving upwards in a magnetic field which is towards north. The particle will be deflected towards
  • East
  • West
  • North
  • South
To convert a galvanometer into an ammeter , we connect
  • low resistance in series
  • low resistance in parallel
  • high resistance in series
  • high resistance in parallel
An electron having mass m and charge q and kinetic energy K enters a uniform magnetic field B perpendicularly. Then its frequency of rotation will be
  • $\frac {qB}{\pi m}$
  • $\frac {qB}{2\pi m}$
  • $\frac {qBE}{2\pi m}$
  • $\frac {qB}{2\pi E}$
A charged particle would continue to move with a constant velocity in a region wherein, (i) E = 0, B ≠ 0 (ii) E ≠  0 B ≠ 0 (iii) E  ≠ 0 B= 0, . (iv) E = 0, B = 0.
  • (i) and (iv)
  • (i) , (ii) and (iv)
  • (i), (iii) and (iv)
  • (iii) and (iv)
Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field $\mathbf{B}=B_0 \mathbf{k}$
  • They have equal z-components of momenta.
  • They must have equal charges
  • They necessarily represent a particle-antiparticle pair
  • The charge to mass ratio satisfy $(\frac {e}{m})_1 +(\frac {e}{m})_2=0$
(a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion : A charge whether stationary or in motion produces a magnetic field around it Reason: Moving charges produce only electric field in the surrounding space
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
(a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: Magnetic field lines are continuous and closed. Reason: Magnetic monopole does not exist.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
(a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: if a proton and an alpha particle enter a uniform magnetic field perpendicularly with the same speed, time period of alpha particle will be double that a proton Reason: The period of revolution of  charged particle is directly proportional to mass of the particle and is inversely proportional to charge of particle
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
(a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: The energy of charged particle moving in a uniform magnetic field changes. Reason: Work done by magnetic field on the charge is non zero.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
(a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: A wire bent into an irregular shape with the points P and Q fixed. If a current I passed through the wire, then the area enclosed by the irregular portion of the wire increases. Reason: Opposite currents carrying wires repel each other
moving-charges-and-magnetism-class12-mcq-3.png
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
If the current density in a linear conductor of radius a varies with r according to the relation $j= kr^2$ Where k is the constant and r is the distance from a point from the axis of the conductor . Find the magnetic field at a point distance r from the axis where r < a
  • $B= \frac {\mu _0 kr^3}{4}$
  • $B= \frac {\mu _0 kr^3}{2}$
  • $B= \frac {3\mu _0 kr^3}{4}$
  • $B= \frac {2\mu _0 kr^3}{3}$
Find the magnetic field at a point distance r from the axis where r > a
  • $B= \frac {3\mu _0 ka^4}{2r}$
  • $B= \frac {\mu _0 ka^4}{3r}$
  • $B= \frac {\mu _0 ka^4}{r}$
  • $B= \frac {\mu _0 ka^4}{4r}$
The coil of a galvanometer is .02 m x .08 m. It consists of 200 turns of fine wire and is in a magnetic field of .2 tesla. The restoring torque constant of the suspension fibre is $10^{-6} \ N m deg^{-1}$. Assuming the magnetic field to be radial. What is the maximum current can be measured by this galvanometer ,if the scale can accommodate $30^0$ deflection?
  • $4.69 \times 10^{-4} $ A
  • $1.69 \times 10^{-4} $ A
  • $4.69 \times 10^{-3} $ A
  • $5.69 \times 10^{-4} $ A
what is the smallest current that can be detected , if the maximum observable deflection is .1 degree?
  • $1.56 \times 10^{-5} \ A$
  • $3.56 \times 10^{-6} \ A$
  • $5.56 \times 10^{-6} \ A$
  • $1.56 \times 10^{-6} \ A$
Which of the following statements is not correct about the magnetic field?
  • magnetic lines of force don’t cut each other
  • tangents to the magnetic lines give the direction of the magnetic field.
  • inside the magnet the lines go from north to south pole of the magnet
  • the magnetic lines from a closed loop
0 h : 0 m : 1 s

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