MCQOPTIONS
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MCQOPTIONS
This section includes 34 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If the current is doubled, the deflection is also doubled in [Orissa JEE 2002] |
| A. | A tangent galvanometer |
| B. | A moving coil galvanometer |
| C. | \[y\] and \[B/A\] |
| D. | None of these |
| Answer» C. \[y\] and \[B/A\] | |
| 2. |
A small cylindrical soft iron piece is kept in a galvanometer so that [MP PMT 2001] |
| A. | A radial uniform magnetic field is produced |
| B. | A uniform magnetic field is produced |
| C. | \[2\pi \sqrt{\frac{ML}{\eta }}\] |
| D. | All of these |
| Answer» E. | |
| 3. |
A long wire A carries a current of 10 amp. Another long wire B, Which is parallel to A and separated by 0.1m from A, carries a current of 5 amp, in the opposite direction to that in A. what is the magnitude and nature of the force experienced per unit length of B \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}\,weber/amp\text{-}m)\] [MP PET 2000] |
| A. | Repulsive force of \[{{10}^{-4}}N/m\] |
| B. | Attractive force of \[{{10}^{-4}}N/m\] |
| C. | 36,000 |
| D. | Attractive force of \[2\pi \times {{10}^{-5}}N/m\] |
| Answer» B. Attractive force of \[{{10}^{-4}}N/m\] | |
| 4. |
In order to increase the sensitivity of a moving coil galvanometer, one should decrease [MP PMT 2000] |
| A. | The strength of its magnet |
| B. | The torsional constant of its suspension |
| C. | If assertion is true but reason is false. |
| D. | The area of its coil |
| Answer» C. If assertion is true but reason is false. | |
| 5. |
Two long parallel copper wires carry currents of 5A each in opposite directions. If the wires are separated by a distance of 0.5m, then the force between the two wires is [EAMCET (Engg.) 2000] |
| A. | \[{{10}^{-5}}N,\,\]attractive |
| B. | \[{{10}^{-5}}N,\,\]repulsive |
| C. | If assertion is true but reason is false. |
| D. | \[2\times {{10}^{-5}}N,\,\]repulsive |
| Answer» C. If assertion is true but reason is false. | |
| 6. |
Magnetic dipole moment of a rectangular loop is [RPET 2000] |
| A. | Inversely proportional to current in loop |
| B. | Inversely proportional to area of loop |
| C. | If assertion is true but reason is false. |
| D. | Perpendicular to plane of loop and proportional to area of loop |
| Answer» E. | |
| 7. |
The current sensitivity of a moving coil galvanometer can be increased by [Roorkee 1999] |
| A. | Increasing the magnetic field of the permanent magnet |
| B. | Increasing the area of the deflecting coil |
| C. | If assertion is true but reason is false. |
| D. | Increasing the restoring couple of the coil |
| Answer» C. If assertion is true but reason is false. | |
| 8. |
A triangular loop of side l carries a current I. It is placed in a magnetic field B such that the plane of the loop is in the direction of B. The torque on the loop is [MP PET 2003] |
| A. | Zero |
| B. | IBl |
| C. | OB |
| D. | \[\frac{\sqrt{3}}{4}IB{{l}^{2}}\] |
| Answer» E. | |
| 9. |
Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is [CPMT 1991; IIT 1986; Bihar MEE 1995; RPMT 1997; MP PET 1996; MP PMT 1994, 96, 99; UPSEAT 2001, 03] |
| A. | \[\frac{{{\mu }_{0}}{{i}^{2}}}{{{b}^{2}}}\] |
| B. | \[\frac{{{\mu }_{0}}{{i}^{2}}}{2\pi b}\] |
| C. | \[\cos e{{c}^{-1}}\left( \frac{H}{{{H}_{0}}} \right)\] |
| D. | \[\frac{{{\mu }_{0}}i}{2\pi {{b}^{2}}}\] |
| Answer» C. \[\cos e{{c}^{-1}}\left( \frac{H}{{{H}_{0}}} \right)\] | |
| 10. |
The coil of a galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is \[{{10}^{-8}}\,N-m/radian\]. The magnetic field between the pole pieces is 5 T. The current sensitivity of this galvanometer will be [MP PMT 1997] |
| A. | \[5\times {{10}^{4}}\,rad/\mu \,amp\] |
| B. | \[5\times {{10}^{-6}}\,per\,amp\] |
| C. | \[H\sqrt{2}\] |
| D. | \[5\,rad/\mu \,amp\] |
| Answer» E. | |
| 11. |
The pole pieces of the magnet used in a pivoted coil galvanometer are [MP PET 1996] |
| A. | Plane surfaces of a bar magnet |
| B. | Plane surfaces of a horse-shoe magnet |
| C. | Can never reach the equator |
| D. | Cylindrical surfaces of a horse-shoe magnet |
| Answer» E. | |
| 12. |
A current carrying circular loop is freely suspended by a long thread. The plane of the loop will point in the direction [MP PMT 1995] |
| A. | Wherever left free |
| B. | North-south |
| C. | In any direction |
| D. | At \[45{}^\circ \] with the east-west direction |
| Answer» D. At \[45{}^\circ \] with the east-west direction | |
| 13. |
A current of 10 ampere is flowing in a wire of length 1.5 m. A force of 15 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is [MP PMT 1994] |
| A. | \[30{}^\circ \] |
| B. | \[45{}^\circ \] |
| C. | Maximum, maximum |
| D. | \[90{}^\circ \] |
| Answer» B. \[45{}^\circ \] | |
| 14. |
Two straight parallel wires, both carrying 10 ampere in the same direction attract each other with a force of\[1\times {{10}^{-3}}N\]. If both currents are doubled, the force of attraction will be [MP PET 1994] |
| A. | \[1\times {{10}^{-3}}\,N\] |
| B. | \[2\times {{10}^{-3}}\,N\] |
| C. | Isogonic line |
| D. | \[0.25\times {{10}^{-3}}\,N\] |
| Answer» D. \[0.25\times {{10}^{-3}}\,N\] | |
| 15. |
An infinitely long conductor PQR is bent to form a right angle as shown. A current I flows through PQR The magnetic field due to this current at the point M is H1. Now another infinitely long straight conductor QS is connected at Q so that the current is I/2 in QR as well as in QS, The current in PQ remaining unchanged. The magnetic field at M is now \[{{H}_{2.}}\]The ratio \[{{H}_{1}}/{{H}_{2}}\] is given by [IIT-JEE (Screening) 2000] |
| A. | \[\frac{1}{2}\] |
| B. | 1 |
| C. | Magnetic line |
| D. | 2 |
| Answer» D. 2 | |
| 16. |
A and B are two conductors carrying a current i in the same direction. x and y are two electron beams moving in the same direction [Karnataka CET (Engg./Med.) 2002] |
| A. | There will be repulsion between A and B attraction between x and y |
| B. | There will be attraction between A and B, repulsion between x and y |
| C. | \[5\times {{10}^{-5}}tesla\] |
| D. | There will be attraction between A and B and also x and y |
| Answer» C. \[5\times {{10}^{-5}}tesla\] | |
| 17. |
A particle of mass m and charge q moves with a constant velocity v along the positive x direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from x = a to x = b. The minimum value of v required so that the particle can just enter the region \[x>b\] is [IIT-JEE (Screening) 2002] |
| A. | \[qb\,B/m\] |
| B. | \[q(b-a)B/m\] |
| C. | kg?1 m3 |
| D. | \[q(b+a)B/2m\] |
| Answer» C. kg?1 m3 | |
| 18. |
A long straight wire along the z-axis carries a current I in the negative z direction. The magnetic vector field \[\overset{\to }{\mathop{B}}\,\] at a point having coordinates (x, y) in the z = 0 plane is [IIT-JEE (Screening) 2002] |
| A. | \[\frac{{{\mu }_{o}}I\,(y\hat{i}-x\hat{j})}{2\pi ({{x}^{2}}+{{y}^{2}})}\] |
| B. | \[\frac{{{\mu }_{o}}I\,(x\hat{i}+y\hat{j})}{2\pi ({{x}^{2}}+{{y}^{2}})}\] |
| C. | \[20\,\,A{{m}^{2}}\] |
| D. | \[\frac{{{\mu }_{o}}I\,(x\hat{i}-y\hat{j})}{2\pi ({{x}^{2}}+{{y}^{2}})}\] |
| Answer» B. \[\frac{{{\mu }_{o}}I\,(x\hat{i}+y\hat{j})}{2\pi ({{x}^{2}}+{{y}^{2}})}\] | |
| 19. |
On connecting a battery to the two corners of a diagonal of a square conductor frame of side \[a\] the magnitude of the magnetic field at the centre will be [MP PET 2002] |
| A. | Zero |
| B. | \[\frac{{{\mu }_{o}}}{\pi a}\] |
| C. | \[\frac{{{\mu }_{0}}}{4\pi }\frac{2\sqrt{2}M}{{{d}^{3}}}\] |
| D. | \[\frac{4{{\mu }_{o}}i}{\pi a}\] |
| Answer» B. \[\frac{{{\mu }_{o}}}{\pi a}\] | |
| 20. |
A long solenoid has n turns per meter and current I A is flowing through it. The magnetic field at the ends of the solenoid is [MP PMT 2001; MP PET 2002] |
| A. | \[\frac{{{\mu }_{0}}nI}{2}\] |
| B. | \[{{\mu }_{0}}nI\] |
| C. | If assertion is true but reason is false. |
| D. | \[2{{\mu }_{0}}nI\] |
| Answer» B. \[{{\mu }_{0}}nI\] | |
| 21. |
Two infinitely long parallel wires carry equal current in same direction. The magnetic field at a mid point in between the two wires is [MP PMT 2001] |
| A. | Twice the magnetic field produced due to each of the wires |
| B. | Half of the magnetic field produced due to each of the wires |
| C. | If assertion is true but reason is false. |
| D. | Zero |
| Answer» E. | |
| 22. |
PQRS is a square loop made of uniform conducting wire the current enters the loop at P and leaves at S. Then the magnetic field will be [KCET 2000] |
| A. | Maximum at the centre of the loop |
| B. | Zero at the centre of loop |
| C. | If assertion is true but reason is false. |
| D. | Zero at all points outside of the loop |
| Answer» C. If assertion is true but reason is false. | |
| 23. |
A straight wire carrying a current 10 A is bent into a semicircular arc of radius 5 cm. The magnitude of magnetic field at the center is [CPMT 2000] |
| A. | \[1.5\times {{10}^{-5}}\,T\] |
| B. | \[3.14\times {{10}^{-5}}\,T\] |
| C. | If assertion is true but reason is false. |
| D. | \[19.6\times {{10}^{-5}}T\] |
| Answer» D. \[19.6\times {{10}^{-5}}T\] | |
| 24. |
Magnetic field due to a ring having n turns at a distance x on its axis is proportional to (if r = radius of ring) [RPET 2000] |
| A. | \[\frac{r}{({{x}^{2}}+{{r}^{2}})}\] |
| B. | \[\frac{{{r}^{2}}}{{{({{x}^{2}}+{{r}^{2}})}^{3/2}}}\] |
| C. | If assertion is true but reason is false. |
| D. | \[\frac{{{n}^{2}}{{r}^{2}}}{{{({{x}^{2}}+{{r}^{2}})}^{3/2}}}\] |
| Answer» D. \[\frac{{{n}^{2}}{{r}^{2}}}{{{({{x}^{2}}+{{r}^{2}})}^{3/2}}}\] | |
| 25. |
Tesla is the unit of [AIIMS 1999] |
| A. | Electric flux |
| B. | Magnetic flux |
| C. | Both (a) and (b) |
| D. | Magnetic field |
| Answer» E. | |
| 26. |
A circular coil ?A? has a radius R and the current flowing through it is I. Another circular coil ?B? has a radius 2R and if 2I is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of (i.e.\[{{B}_{A}}\] to \[{{B}_{B}}\]) [CBSE PMT1993; AIEEE 2002] |
| A. | 4 : 1 |
| B. | 2 : 1 |
| C. | There is a steady deflection of the coil |
| D. | 1 : 1 |
| Answer» E. | |
| 27. |
The expression for magnetic induction inside a solenoid of length L carrying a current I and having N number of turns is [MP PMT/PET 1998] |
| A. | \[\frac{{{\mu }_{0}}}{4\pi }\frac{N}{LI}\] |
| B. | \[{{\mu }_{0}}NI\] |
| C. | Repulsive force of \[2\pi \times {{10}^{-5}}N/m\] |
| D. | \[{{\mu }_{0}}\frac{N}{L}I\] |
| Answer» E. | |
| 28. |
The magnetic field \[d\overrightarrow{B}\] due to a small current element \[d\overrightarrow{l\,}\] at a distance \[\overrightarrow{r\,}\] and element carrying current i is, or Vector form of Biot-savart's law is [CBSE PMT 1996; MP PET 2002; MP PMT 2000] |
| A. | \[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }i\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{r} \right)\] |
| B. | \[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }{{i}^{2}}\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{r} \right)\] |
| C. | The number of turns in its coil |
| D. | \[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }i\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{{{r}^{3}}} \right)\] |
| Answer» E. | |
| 29. |
A solenoid is 1.0 metre long and it has 4250 turns. If a current of 5.0 ampere is flowing through it, what is the magnetic field at its centre \[[{{\mu }_{0}}=4\pi \times {{10}^{-7}}\,weber/amp-m]\] [MP PMT 1996] |
| A. | \[5.4\times {{10}^{-2}}\,weber/{{m}^{2}}\] |
| B. | \[2.7\times {{10}^{-2}}\,weber/{{m}^{2}}\] |
| C. | \[2\times {{10}^{-5}}N,\,\]attractive |
| D. | \[0.675\times {{10}^{-2}}\,weber/{{m}^{2}}\] |
| Answer» C. \[2\times {{10}^{-5}}N,\,\]attractive | |
| 30. |
The magnetic field B with in the solenoid having n turns per metre length and carrying a current of i ampere is given by [MP PET 1993] |
| A. | \[\frac{{{\mu }_{0}}ni}{e}\] |
| B. | \[{{\mu }_{0}}ni\] |
| C. | Parallel to plane of loop and proportional to area of loop |
| D. | ni |
| Answer» C. Parallel to plane of loop and proportional to area of loop | |
| 31. |
Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moment is [DCE 2002] |
| A. | 2 : p |
| B. | p : 2 |
| C. | Increasing the number of turns in the coil |
| D. | 4 : p |
| Answer» D. 4 : p | |
| 32. |
Two similar coils are kept mutually perpendicular such that their centres coincide. At the centre, find the ratio of the magnetic field due to one coil and the resultant magnetic field by both coils, if the same current is flown [BHU 2003; CPMT 2004] |
| A. | 1: \[\sqrt{2}\] |
| B. | 1 : 2 |
| C. | \[\frac{\sqrt{3}}{2}I{{l}^{2}}{{B}^{2}}\] |
| D. | \[\sqrt{3}\,\,:\,\,1\] |
| Answer» B. 1 : 2 | |
| 33. |
A wire in the form of a circular loop of one turn carrying a current produces a magnetic field B at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is [CBSE 2002; KCET 2003] |
| A. | \[5B\] |
| B. | \[3B\] |
| C. | \[\frac{{{\mu }_{0}}i}{2\pi b}\] |
| D. | \[4B\] |
| Answer» E. | |
| 34. |
Assertion : The coil is bound over the metallic frame in moving coil galvanometer. Reason : The metallic frame help in making steady deflection without any oscillation. |
| A. | If both assertion and reason are true and the reason is the correct explanation of the assertion. |
| B. | If both assertion and reason are true but reason is not the correct explanation of the assertion. |
| C. | \[2\times {{10}^{-7}}\,per\,amp\] |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion. | |