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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 5651. |
A long magnet is cut in two parts in such a way that the ratio of their lengths is 2 : 1. The ratio of pole strengths of both the section is [CPMT 1986] |
| A. | Equal |
| B. | In the ratio of 2 : 1 |
| C. | In the ratio of 1 : 2 |
| D. | In the ratio of 4 : 1 |
| Answer» B. In the ratio of 2 : 1 | |
| 5652. |
A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180o will be [MP PMT 1985; MP PET 1997] |
| A. | \[-MB\] |
| B. | \[+MB\] |
| C. | 0 |
| D. | \[+2MB\] |
| Answer» E. | |
| 5653. |
Two small bar magnets are placed in a line with like poles facing each other at a certain distance d apart. If the length of each magnet is negligible as compared to d, the force between them will be inversely proportional to [CPMT 1971; NCERT 1971; MP PMT 1992] |
| A. | \[d\] |
| B. | \[{{d}^{2}}\] |
| C. | \[\frac{1}{{{d}^{2}}}\] |
| D. | \[{{d}^{4}}\] |
| Answer» E. | |
| 5654. |
If a bar magnet of magnetic moment M is freely suspended in a uniform magnetic field of strength B, the work done in rotating the magnet through an angle\[\theta \] is [AFMC 1997; MNR 1998; RPET 1999; MP PMT 1989, 96, 99; MP PET 1984, 89, 2000; UPSEAT 1999, 2000, 05] |
| A. | \[MB(1-\sin \theta )\] |
| B. | \[MB\sin \theta \] |
| C. | \[MB\cos \theta \] |
| D. | \[MB(1-\cos \theta )\] |
| Answer» E. | |
| 5655. |
Two short magnets with their axes horizontal and perpendicular to the magnetic meridian are placed with their centres 40 cm east and 50 cm west of magnetic needle. If the needle remains undeflected, the ratio of their magnetic moments \[{{M}_{1}}:{{M}_{2}}\] is [MP PET 1990] |
| A. | 4 : 5 |
| B. | 16 : 25 |
| C. | 64 : 125 |
| D. | \[2:\sqrt{5}\] |
| Answer» D. \[2:\sqrt{5}\] | |
| 5656. |
Points A and B are situated perpendicular to the axis of a 2cm long bar magnet at large distances X and 3X from its centre on opposite sides. The ratio of the magnetic fields at A and B will be approximately equal to [CPMT 1988] |
| A. | 1 : 9 |
| B. | 2 : 9 |
| C. | 27 : 1 |
| D. | 9 : 1 |
| Answer» D. 9 : 1 | |
| 5657. |
The figure below shows the north and south poles of a permanent magnet in which n turn coil of area of cross-section A is resting, such that for a current i passed through the coil, the plane of the coil makes an angle \[\theta \]with respect to the direction of magnetic field B. If the plane of the magnetic field and the coil are horizontal and vertical respectively, the torque on the coil will be [CPMT 1986, 88; DPMT 2002] |
| A. | \[\tau =niAB\cos \theta \] |
| B. | \[\tau =niAB\sin \theta \] |
| C. | \[\tau =niAB\] |
| D. | None of the above, since the magnetic field is radial |
| Answer» B. \[\tau =niAB\sin \theta \] | |
| 5658. |
A uniform magnetic field, parallel to the plane of the paper existed in space initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by [CPMT 1986, 88] |
| A. | Figure |
| B. | Figure |
| C. | Figure |
| D. | Figure |
| Answer» C. Figure | |
| 5659. |
Unit of magnetic flux density (or magnetic induction) is [DPMT 1988;CPMT 1984, 78, 90; MP PMT 1992; MH CET 2004] |
| A. | Tesla |
| B. | Weber/metre2 |
| C. | Newton/ampere-metre |
| D. | All of the above |
| Answer» E. | |
| 5660. |
The field due to a magnet at a distance R from the centre of the magnet is proportional to [MP PET 1996] |
| A. | \[{{R}^{2}}\] |
| B. | \[{{R}^{3}}\] |
| C. | \[1/{{R}^{2}}\] |
| D. | \[1/{{R}^{3}}\] |
| Answer» E. | |
| 5661. |
A sensitive magnetic instrument can be shielded very effectively from outside magnetic fields by placing it inside a box of [CPMT 1974] |
| A. | Teak wood |
| B. | Plastic material |
| C. | Soft iron of high permeability |
| D. | A metal of high conductivity |
| Answer» D. A metal of high conductivity | |
| 5662. |
Which of the following, the most suitable material for making permanent magnet is |
| A. | Steel |
| B. | Soft iron |
| C. | Copper |
| D. | Nickel |
| Answer» B. Soft iron | |
| 5663. |
The magnetic field due to a short magnet at a point on its axis at distance X cm from the middle point of the magnet is 200 Gauss. The magnetic field at a point on the neutral axis at a distance X cm from the middle of the magnet is [CPMT 1971, 88; MP PET 1985] |
| A. | 100 Gauss |
| B. | 400 Gauss |
| C. | 50 Gauss |
| D. | 200 Gauss |
| Answer» B. 400 Gauss | |
| 5664. |
A bar magnet having centre O has a length of 4 cm. Point P1 is in the broad side-on and P2 is in the end side-on position with OP1 = OP2 = 10 metres. The ratio of magnetic intensities H at P1 and P2 is [MP PET 1990] |
| A. | \[{{H}_{1}}:{{H}_{2}}=16:100\] |
| B. | \[{{H}_{1}}:{{H}_{2}}=1:2\] |
| C. | \[{{H}_{1}}:{{H}_{2}}=2:1\] |
| D. | \[{{H}_{1}}:{{H}_{2}}=100:16\] |
| Answer» C. \[{{H}_{1}}:{{H}_{2}}=2:1\] | |
| 5665. |
A magnet of magnetic moment 20 C.G.S. units is freely suspended in a uniform magnetic field of intensity 0.3 C.G.S. units. The amount of work done in deflecting it by an angle of 30o in C.G.S. units is [MP PET 1991] |
| A. | 6 |
| B. | \[3\sqrt{3}\] |
| C. | \[3(2-\sqrt{3)}\] |
| D. | \[3\] |
| Answer» D. \[3\] | |
| 5666. |
The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the centre of the magnet is [MP PMT 1990] |
| A. | \[{{2}^{-3}}\] |
| B. | \[{{2}^{-1/3}}\] |
| C. | \[{{2}^{3}}\] |
| D. | \[{{2}^{1/3}}\] |
| Answer» E. | |
| 5667. |
The pole strength of a bar magnet is 48 ampere-metre and the distance between its poles is 25 cm. The moment of the couple by which it can be placed at an angle of 30o with the uniform magnetic intensity of flux density 0.15 Newton /ampere-metre will be |
| A. | 12 Newton × metre |
| B. | 18 Newton × metre |
| C. | 0.9 Newton × metre |
| D. | None of the above |
| Answer» D. None of the above | |
| 5668. |
The magnetism of magnet is due to [JIPMER 1997] |
| A. | The spin motion of electron |
| B. | Earth |
| C. | Pressure of big magnet inside the earth |
| D. | Cosmic rays |
| Answer» B. Earth | |
| 5669. |
An iron rod of length L and magnetic moment M is bent in the form of a semicircle. Now its magnetic moment will be [CPMT 1984; MP Board 1986; NCERT 1975; MP PET/PMT 1988; EAMCET (Med.) 1995; Manipal MEE 1995;RPMT 1996; BHU 1995; MP PET 2002] |
| A. | \[M\] |
| B. | \[\frac{2M}{\pi }\] |
| C. | \[\frac{M}{\pi }\] |
| D. | \[M\pi \] |
| Answer» C. \[\frac{M}{\pi }\] | |
| 5670. |
How many minimum number of non-zero vectors in different planes can be added to give zero resultant |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» D. 5 | |
| 5671. |
If a body is in equilibrium under a set of non-collinear forces, then the minimum number of forces has to be [AIIMS 2000] |
| A. | Four |
| B. | Three |
| C. | Two |
| D. | Five |
| Answer» C. Two | |
| 5672. |
A body is in equilibrium under the action of three coplanar forces P, Q and R as shown in the figure. Select the correct statement [AFMC 1994] |
| A. | \[\frac{P}{\sin \alpha }=\frac{Q}{\sin \beta }=\frac{R}{\sin \gamma }\] |
| B. | \[\frac{P}{\cos \alpha }=\frac{Q}{\cos \beta }=\frac{R}{\cos \gamma }\] |
| C. | \[\frac{P}{\tan \alpha }=\frac{Q}{\tan \beta }=\frac{R}{\tan \gamma }\] |
| D. | \[\frac{P}{\sin \beta }=\frac{Q}{\sin \gamma }=\frac{R}{\sin \alpha }\] |
| Answer» B. \[\frac{P}{\cos \alpha }=\frac{Q}{\cos \beta }=\frac{R}{\cos \gamma }\] | |
| 5673. |
P, Q and R are three coplanar forces acting at a point and are in equilibrium. Given P = 1.9318 kg wt, \[\sin {{\theta }_{1}}=\]0.9659, the value of R is ( in kg wt) [CET 1998] |
| A. | 0.9659 |
| B. | 2 |
| C. | 1 |
| D. | \[\frac{1}{2}\] |
| Answer» D. \[\frac{1}{2}\] | |
| 5674. |
Kirchhoff's second law is based on the law of conservation of [RPET 2003; MH CET 2001] |
| A. | Charge |
| B. | Energy |
| C. | Momentum |
| D. | Sum of mass and energy |
| Answer» C. Momentum | |
| 5675. |
A cell of constant e.m.f. first connected to a resistance \[{{R}_{1}}\] and then connected to a resistance \[{{R}_{2}}\]. If power delivered in both cases is then the internal resistance of the cell is [Orissa JEE 2005] |
| A. | \[\sqrt{{{R}_{1}}{{R}_{2}}}\] |
| B. | \[\sqrt{\frac{{{R}_{1}}}{{{R}_{2}}}}\] |
| C. | \[\frac{{{R}_{1}}-{{R}_{2}}}{2}\] |
| D. | \[\frac{{{R}_{1}}+{{R}_{2}}}{2}\] |
| Answer» B. \[\sqrt{\frac{{{R}_{1}}}{{{R}_{2}}}}\] | |
| 5676. |
The n rows each containing m cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of 3W resistance. If the total number of cells used are 24 and internal resistance of each cell is 0.5 W then [J & K CET 2005] |
| A. | \[m=8,n=3\] |
| B. | \[m=6,n=4\] |
| C. | \[m=12,n=2\] |
| D. | \[m=2,n=12\] |
| Answer» D. \[m=2,n=12\] | |
| 5677. |
The figure shows a network of currents. The magnitude of currents is shown here. The current I will be [BCECE 2005] |
| A. | 3 A |
| B. | 9 A |
| C. | 13 A |
| D. | 19 A |
| Answer» D. 19 A | |
| 5678. |
To draw maximum current from a combination of cells, how should the cells be grouped [AFMC 2005] |
| A. | Series |
| B. | Parallel |
| C. | Mixed |
| D. | Depends upon the relative values of external and internal resistance |
| Answer» E. | |
| 5679. |
The magnitude of i in ampere unit is [KCET 2005] |
| A. | 0.1 |
| B. | 0.3 |
| C. | 0.6 |
| D. | None of these |
| Answer» B. 0.3 | |
| 5680. |
An energy source will supply a constant current into the load if its internal resistance is [AIEEE 2005] |
| A. | Zero |
| B. | Non-zero but less than the resistance of the load |
| C. | Equal to the resistance of the load |
| D. | Very large as compared to the load resistance |
| Answer» E. | |
| 5681. |
Kirchhoff's first law \[i.e.\] \[\Sigma i=0\] at a junction is based on the law of conservation of [CBSE PMT 1997; AIIMS 2000; MP PMT 2002; RPMT 2001; DPMT 2005] |
| A. | Charge |
| B. | Energy |
| C. | Momentum |
| D. | Angular momentum |
| Answer» B. Energy | |
| 5682. |
Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are \[{{R}_{1}}\] and \[{{R}_{2}}\,({{R}_{2}}>{{R}_{1}})\]. If the potential difference across the source having internal resistance \[{{R}_{2}}\] is zero, then [AIEEE 2005] |
| A. | \[R={{R}_{1}}{{R}_{2}}/({{R}_{1}}+{{R}_{2}})\] |
| B. | \[R={{R}_{1}}{{R}_{2}}/({{R}_{2}}-{{R}_{1}})\] |
| C. | \[R={{R}_{2}}\times ({{R}_{1}}+{{R}_{2}})/({{R}_{2}}-{{R}_{1}})\] |
| D. | \[R={{R}_{2}}-{{R}_{1}}\] |
| Answer» E. | |
| 5683. |
Two batteries, one of emf 18 volts and internal resistance \[2\Omega \] and the other of emf 12 volt and internal resistance \[1\Omega \], are connected as shown. The voltmeter \[V\]will record a reading of [CBSE PMT 2005] |
| A. | 15 volt |
| B. | 30 volt |
| C. | 14 volt |
| D. | 18 volt |
| Answer» D. 18 volt | |
| 5684. |
Find out the value of current through 2W resistance for the given circuit [IIT-JEE (Screening) 2005] |
| A. | 5 A |
| B. | 2 A |
| C. | Zero |
| D. | 4 A |
| Answer» D. 4 A | |
| 5685. |
The maximum power drawn out of the cell from a source is given by (where r is internal resistance) [DCE 2002] |
| A. | \[{{E}^{2}}/2r\] |
| B. | \[{{E}^{2}}/4r\] |
| C. | \[{{E}^{2}}/r\] |
| D. | \[{{E}^{2}}/3r\] |
| Answer» C. \[{{E}^{2}}/r\] | |
| 5686. |
When the resistance of 9 W is connected at the ends of a battery, its potential difference decreases from 40 volt to 30 volt. The internal resistance of the battery is [DPMT 2003] |
| A. | 6 W |
| B. | 3 W |
| C. | 9 W |
| D. | 15 W |
| Answer» C. 9 W | |
| 5687. |
A capacitor is connected to a cell of emf E having some internal resistance r. The potential difference across the [CPMT 2004; MP PMT 2005] |
| A. | Cell is < E |
| B. | Cell is E |
| C. | Capacitor is > E |
| D. | Capacitor is < E |
| Answer» C. Capacitor is > E | |
| 5688. |
In the given current distribution what is the value of I [Orissa PMT 2004] |
| A. | 3A |
| B. | 8 A |
| C. | 2A |
| D. | 5A |
| Answer» D. 5A | |
| 5689. |
A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharge is 14 V. The "Watt-hour" efficiency of the battery is [CBSE PMT 2004] |
| A. | 82.5% |
| B. | 80 % |
| C. | 90% |
| D. | 87.5% |
| Answer» E. | |
| 5690. |
Current provided by a battery is maximum when [AFMC 2004] |
| A. | Internal resistance equal to external resistance |
| B. | Internal resistance is greater than external resistance |
| C. | Internal resistance is less than external resistance |
| D. | None of these |
| Answer» B. Internal resistance is greater than external resistance | |
| 5691. |
Eels are able to generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in 100 rows, each row stretching horizontally along the body of the fish containing 5000 electroplaques. The arrangement is suggestively shown below. Each electroplaques has an emf of 0.15 V and internal resistance of 0.25 W [AIIMS 2004] The water surrounding the eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of 500 W, the current an eel can produce in water is about |
| A. | 1.5 A |
| B. | 3.0 A |
| C. | 15 A |
| D. | 30 A |
| Answer» B. 3.0 A | |
| 5692. |
Two cells, e.m.f. of each is \[E\] and internal resistance \[r\] are connected in parallel between the resistance \[R\]. The maximum energy given to the resistor will be, only when [MNR 1988; MP PET 2000; UPSEAT 2001] |
| A. | \[R=r/2\] |
| B. | \[R=r\] |
| C. | \[R=2r\] |
| D. | \[R=0\] |
| Answer» B. \[R=r\] | |
| 5693. |
In the above question, if the internal resistance of the battery is 1 ohm, then what is the reading of ammeter |
| A. | 5/3 A |
| B. | 40/29 A |
| C. | 10/9 A |
| D. | 1 A |
| Answer» C. 10/9 A | |
| 5694. |
In the circuit, the reading of the ammeter is (assume internal resistance of the battery be zero) |
| A. | \[\frac{40}{29}A\] |
| B. | \[\frac{10}{9}A\] |
| C. | \[\frac{5}{3}A\] |
| D. | 2 A |
| Answer» E. | |
| 5695. |
Kirchoff?s I law and II law of current, proves the [CBSE PMT 1993; BHU 2002; AFMC 2003] |
| A. | Conservation of charge and energy |
| B. | Conservation of current and energy |
| C. | Conservation of mass and charge |
| D. | None of these |
| Answer» B. Conservation of current and energy | |
| 5696. |
The emf of a battery is 2 V and its internal resistance is 0.5 W. The maximum power which it can deliver to any external circuit will be [AMU (Med.) 2002] |
| A. | 8 Watt |
| B. | 4 Watt |
| C. | 2 Watt |
| D. | None of the above |
| Answer» D. None of the above | |
| 5697. |
The internal resistance of a cell is the resistance of [BHU 1999, 2000; AIIMS 2001] |
| A. | Electrodes of the cell |
| B. | Vessel of the cell |
| C. | Electrolyte used in the cell |
| D. | Material used in the cell |
| Answer» D. Material used in the cell | |
| 5698. |
When a resistor of 11 W is connected in series with an electric cell, the current flowing in it is 0.5 A. Instead, when a resistor of 5 W is connected to the same electric cell in series, the current increases by 0.4 A. The internal resistance of the cell is [EAMCET 2001] |
| A. | 1.5 W |
| B. | 2 W |
| C. | 2.5 W |
| D. | 3.5 W |
| Answer» D. 3.5 W | |
| 5699. |
Two batteries A and B each of e.m.f. 2 V are connected in series to an external resistance R = 1 ohm. If the internal resistance of battery A is 1.9 ohms and that of B is 0.9 ohm, what is the potential difference between the terminals of battery A [MP PET 2001] |
| A. | 2 V |
| B. | 3.8 V |
| C. | Zero |
| D. | None of the above |
| Answer» D. None of the above | |
| 5700. |
A battery has e.m.f. 4 V and internal resistance r. When this battery is connected to an external resistance of 2 ohms, a current of 1 amp. flows in the circuit. How much current will flow if the terminals of the battery are connected directly [MP PET 2001] |
| A. | 1 amp |
| B. | 2 amp |
| C. | 4 amp |
| D. | Infinite |
| Answer» C. 4 amp | |