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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.
| 2651. |
What is the self-inductance of a coil which produces 5V when the current changes from 3 ampere to 2 ampere in one millisecond? |
| A. | 5000 henry |
| B. | 5 milli-henry |
| C. | 50 henry |
| D. | 5 henry |
| Answer» C. 50 henry | |
| 2652. |
Two inductances \[{{L}_{1}}\] and \[{{L}_{2}}\]are placed closer and in parallel. Their combined inductance is |
| A. | \[\frac{{{L}_{1}}{{L}_{2}}}{{{L}_{1}}+{{L}_{2}}}\] |
| B. | \[({{L}_{1}}+{{L}_{2}})\] |
| C. | \[({{L}_{1}}+{{L}_{2}})\,\frac{{{L}_{1}}}{{{L}_{2}}}\] |
| D. | \[({{L}_{1}}+{{L}_{2}})\,\frac{{{L}_{2}}}{{{L}_{1}}}\] |
| Answer» B. \[({{L}_{1}}+{{L}_{2}})\] | |
| 2653. |
Two coils are at fixed locations. Which coil 1 has no current and the current in coil 2 increases at the rate of \[15.0\,A\,{{s}^{-1}}\], the emf in coil 1 is 25 mV, when coil 2 has no current and coil 1 has a current of 3.6 A, the flux linkage on coil 2 is |
| A. | 16 m Wb |
| B. | 10 m Wb |
| C. | 4.00 m Wb |
| D. | 6.00 m Wb |
| Answer» E. | |
| 2654. |
A superconducting loop of radius R has self-inductance L. A uniform and constant magnetic field B is applied perpendicular to the plane of the loop. Initially current in this loop is zero. The loop is rotated by \[180{}^\circ \]. The current in the loop after rotation is equal to |
| A. | zero |
| B. | \[\frac{B\pi {{R}^{2}}}{L}\] |
| C. | \[\frac{2B\pi {{R}^{2}}}{L}\] |
| D. | \[\frac{B\pi {{R}^{2}}}{2L}\] |
| Answer» D. \[\frac{B\pi {{R}^{2}}}{2L}\] | |
| 2655. |
A bar magnet was pulled away from a hollow coil A as shown in fig. As the South Pole came out of the coil, the bar magnet next to hollow coil B experienced a magnetic force |
| A. | to the right |
| B. | to the left |
| C. | upward |
| D. | equal to zero |
| Answer» B. to the left | |
| 2656. |
The approximate formula expressing the formula of mutual inductance of two thin coaxial loops of the same radius a when their centers are separated by a distance \[l\] with \[l\] >>a is |
| A. | \[\frac{1}{2}\,\frac{{{\mu }_{0}}\pi {{a}^{4}}}{{{l}^{3}}}\] |
| B. | \[\frac{1}{2}\,\frac{{{\mu }_{0}}\pi {{a}^{4}}}{{{l}^{2}}}\] |
| C. | \[\frac{{{\mu }_{0}}}{4\pi }\frac{\pi {{a}^{4}}}{{{l}^{2}}}\] |
| D. | \[\frac{{{\mu }_{0}}}{\pi }\frac{{{a}^{4}}}{{{l}^{3}}}\] |
| Answer» B. \[\frac{1}{2}\,\frac{{{\mu }_{0}}\pi {{a}^{4}}}{{{l}^{2}}}\] | |
| 2657. |
A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across thering when its speed is v, is: |
| A. | Zero |
| B. | \[Bv\pi {{r}^{2}}/2\] and P is at higher potential |
| C. | \[\pi rBv\] and R is at higher potential |
| D. | 2rBv and R is at higher potential |
| Answer» E. | |
| 2658. |
A cylindrical region of radius 1 m has instantaneous homogenous magnetic field of 5T and it is increasing at a rate of 2T/s. A regular hexagonal loop ABCDEFA of side 1 m is being drawn in to the region with a constant speed of 1 m/s as shown in the figure. What is the magnitude of emf developed in the loop just after the shown instant when the corner A of the hexagon is coinciding with the centre of the circle? |
| A. | \[5/\sqrt{3}V\] |
| B. | \[2\pi /\sqrt{3}V\] |
| C. | \[(5\sqrt{3}+2\pi /3)\,V\] |
| D. | \[(5\sqrt{3}+\pi )\,V\] |
| Answer» D. \[(5\sqrt{3}+\pi )\,V\] | |
| 2659. |
An aluminium ring hangs vertically from a thread with its axis pointing east - west. A coil is fixed near to the ring and coaxial with it. What is the initial motion of the aluminium ring when the current in the coil is switched on? |
| A. | moves toward E |
| B. | moves toward W |
| C. | moves toward N |
| D. | moves toward S |
| Answer» B. moves toward W | |
| 2660. |
A resistance less ring has 2 bulbs A and B rated at 2V, 19 W and 2V, 29 W respectively. The ring encloses an ideal solenoid whose magnetic field is as shown. The radius of solenoid is 1 m and the number of turns/length =1000/m. The current changes at rate of 9 A/sec Find the value of P if power dissipated in bulb B is \[180{}^\circ \] watt. |
| A. | 4 |
| B. | 6 |
| C. | 8 |
| D. | 11 |
| Answer» B. 6 | |
| 2661. |
A horizontal ring of radius \[r=\frac{1}{2}m\] is kept in a vertical constant magnetic field 1 T. The ring is collapsed from maximum area to zero area in 1 s. Then the emf induced in the ring is |
| A. | 1 V |
| B. | \[(\pi /4)V\] |
| C. | \[(\pi /2)V\] |
| D. | \[\pi \,V\] |
| Answer» C. \[(\pi /2)V\] | |
| 2662. |
A rectangular loop PQRS, is pulled with constant speed into a uniform transverse magnetic field by a force F (as shown). E.m.f. induced in side PS and potential difference between points P and S respectively are (Resistance of the loop = r) |
| A. | zero, \[\frac{Fr}{B\ell }\] |
| B. | zero, zero |
| C. | zero, \[\frac{Fr}{6B\ell }\] |
| D. | \[\frac{Fr}{6B\ell },\,\frac{Fr}{6B\ell }\] |
| Answer» D. \[\frac{Fr}{6B\ell },\,\frac{Fr}{6B\ell }\] | |
| 2663. |
A rectangular coil of 20 turns and area of cross- section 25 sq. cm has a resistance of\[100\,\Omega \]. If a magnetic field which is perpendicular to the plane of coil changes at a rate of 1000 tesla per second, the current in the coil is |
| A. | 1 A |
| B. | 50 A |
| C. | 0.5 A |
| D. | 0.208333333333333 |
| Answer» D. 0.208333333333333 | |
| 2664. |
PQ is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is |
| A. | \[\frac{1}{vR}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\,\left( \frac{b}{a} \right) \right]}^{2}}\] |
| B. | \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{a}{b} \right) \right]}^{2}}\frac{1}{vR}\] |
| C. | \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{v}{R}\] |
| D. | \[\frac{v}{R}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{a}{b} \right) \right]}^{2}}\] |
| Answer» B. \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{a}{b} \right) \right]}^{2}}\frac{1}{vR}\] | |
| 2665. |
A coil of resistance 400Q is placed in a magnetic field. If the magnetic flux \[\phi \] (wb) linked with the coil varies with time t (sec) as\[\phi =50{{t}^{2}}+4\]. The current in the coil at t=2 sec is: |
| A. | 0.5 A |
| B. | 0.1 A |
| C. | 2 A |
| D. | 0.0416666666666667 |
| Answer» B. 0.1 A | |
| 2666. |
A coil having n turns and resistance \[R\Omega \]. Is connected with a galvanometer of resistance\[4R\,\Omega \]. This combination is moved in time t second from a magnetic flux \[{{\phi }_{1}}\]weber to\[{{\phi }_{2}}\] weber. The induced current in the circuit is |
| A. | \[-\frac{{{\phi }_{2}}-{{\phi }_{1}}}{5\,Rnt}\] |
| B. | \[-\frac{n({{\phi }_{2}}-{{\phi }_{1}})}{5\,Rt}\] |
| C. | \[-\frac{({{\phi }_{2}}-{{\phi }_{1}})}{\,Rnt}\] |
| D. | \[-\frac{n({{\phi }_{2}}-{{\phi }_{1}})}{\,Rt}\] |
| Answer» C. \[-\frac{({{\phi }_{2}}-{{\phi }_{1}})}{\,Rnt}\] | |
| 2667. |
A plane loop, shaped as two squares of sides a =1 m and b=0.4 m is introduced into a uniform magnetic field\[\bot \]to the plane of loop. The magnetic field varies as \[B={{10}^{-3}}\sin \](100t) T. The amplitude of the current induced in the loop if its resistance per unit length is\[r=5\,m{{\Omega }^{-1}}\]is |
| A. | 0.0833333333333333 |
| B. | 3 A |
| C. | 0.166666666666667 |
| D. | 5 A |
| Answer» C. 0.166666666666667 | |
| 2668. |
A copper rod of length 0.19 m is moving parallel to a long wire with a uniform velocity of 10 m/s. The long wire carries 5 ampere current and is perpendicular to the rod. The ends of the rod are at distances 0.01 m and 0.2 m from the wire. The emf induced in the rod will be- |
| A. | \[10\,\mu V\] |
| B. | \[20\,\mu V\] |
| C. | \[30\,\mu V\] |
| D. | \[40\,\mu V\] |
| Answer» D. \[40\,\mu V\] | |
| 2669. |
A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in the figure. An electric field is induced |
| A. | in AD, but not in BC |
| B. | in BC, but not in AD |
| C. | neither in AD nor in BC |
| D. | in both AD and BC |
| Answer» E. | |
| 2670. |
An equilateral triangular loop having a resistance R and length of each side\[\ell \]is placed in magnetic field which is varying at \[\frac{dB}{dt}=1\,T/s\]. The induced current in the loop will be |
| A. | \[\frac{\sqrt{3}}{4}\frac{{{\ell }^{2}}}{R}\] |
| B. | \[\frac{4}{\sqrt{3}}\frac{{{\ell }^{2}}}{R}\] |
| C. | \[\frac{\sqrt{3}}{4}\,\frac{R}{{{\ell }^{2}}}\] |
| D. | \[\frac{4}{\sqrt{3}}\frac{R}{{{\ell }^{2}}}\] |
| Answer» B. \[\frac{4}{\sqrt{3}}\frac{{{\ell }^{2}}}{R}\] | |
| 2671. |
A uniform magnetic field of induction B is confined to a cylindrical region of radius R. The magnetic field is increasing at a constant rate of \[\frac{dB}{dt}\] (tesla/second). An electron of charge q, placed at the point P on the periphery of the field experiences an acceleration. |
| A. | \[\frac{BR}{(\sqrt{2}+1)m}\] towards left |
| B. | \[\frac{1}{2}\,\frac{eR}{m}\,\frac{dB}{dt}\] towards left |
| C. | \[\frac{eR}{m}\frac{dB}{dt}\] towards left |
| D. | zero |
| Answer» C. \[\frac{eR}{m}\frac{dB}{dt}\] towards left | |
| 2672. |
A conducting wire xy of length\[l\]and mass m is sliding without friction on vertical conduction rails ab and cd shown in Fig. A uniform magnetic field B exists perpendicular to the plane of the rails, x moves with a constant velocity of |
| A. | \[\frac{mgR}{Bl}\] |
| B. | \[\frac{mgR}{B{{l}^{2}}}\] |
| C. | \[\frac{mgR}{{{B}^{2}}{{l}^{2}}}\] |
| D. | \[\frac{mgR}{{{B}^{2}}l}\] |
| Answer» D. \[\frac{mgR}{{{B}^{2}}l}\] | |
| 2673. |
A wire is bent to form the double loop shown in Fig. There is a uniform magnetic field directed into the plane of the loop. If the magnitude of this field is decreasing, the current will flow from |
| A. | a to b and c to d |
| B. | b to a and d to c |
| C. | a to b and d to c |
| D. | b to a and c to d |
| Answer» D. b to a and c to d | |
| 2674. |
A 0.1 m long conductor carrying a current of 50 I A is perpendicular to a magnetic field of 1.21 mT. The mechanical power to move the conductor 1 with a speed of \[1\,m{{s}^{-1}}\] is |
| A. | 0.25 m W |
| B. | 6.25 m W |
| C. | 0.625 W |
| D. | 1W |
| Answer» C. 0.625 W | |
| 2675. |
A rod PQ of length L moves with a uniform velocity v parallel to a long straight wire carrying a current i, the end P remaining at a distance r from the wire. The emf induced across the rod is |
| A. | \[\frac{{{\mu }_{0}}i{{v}^{2}}}{2\pi }ln\,\left( \frac{r+L}{R} \right)\] |
| B. | \[\vec{B}\] |
| C. | \[\frac{{{\mu }_{0}}iv}{2\pi }ln\,\left( \frac{r+L}{R} \right)\] |
| D. | \[\frac{{{\mu }_{0}}iv}{2\pi }ln\,\left( \frac{{{r}^{2}}+{{L}^{2}}}{{{L}^{2}}} \right)\] |
| Answer» D. \[\frac{{{\mu }_{0}}iv}{2\pi }ln\,\left( \frac{{{r}^{2}}+{{L}^{2}}}{{{L}^{2}}} \right)\] | |
| 2676. |
A thin circular ring of area A is perpendicular to uniform magnetic field of induction B. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of circuit is R. When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is |
| A. | \[\frac{BR}{A}\] |
| B. | \[\frac{AB}{R}\] |
| C. | ABR |
| D. | \[{{B}^{2}}\,A/{{R}^{2}}\] |
| Answer» C. ABR | |
| 2677. |
A sliding wire of length 0.25 m and having a resistance of \[0.5\Omega \] moves along conducting guiding rails AB and CD with a uniform speed of 4 m/s. A magnetic field of 0.5 T exists normal to the plane of ABCD directed into the page. The guides are short -circuited with resistances of 4 and \[2\,\Omega \] as shown. The current through the sliding wire is: |
| A. | 0.27 A |
| B. | 0.37 A |
| C. | 1.0 A |
| D. | 0.72A |
| Answer» B. 0.37 A | |
| 2678. |
An L-shaped conductor rod is moving in transverse magnetic field as shown in the figure. Potential difference between ends of the rod is maximum if the rod is moving with velocity |
| A. | \[4\hat{i}-6\hat{j}\,m/s\] |
| B. | \[-\,4\hat{i}+6\hat{j}\,m/s\] |
| C. | \[3\hat{i}+2\hat{j}\,m/s\] |
| D. | \[\sqrt{13}\hat{i}\,m/s\] |
| Answer» D. \[\sqrt{13}\hat{i}\,m/s\] | |
| 2679. |
The magnetic field in a region is given by \[B={{B}_{0}}\left( 1+\frac{x}{a} \right)\hat{k}\]. A square loop of edge-length d is placed with its edges along the x and y-axes. The loop is moved with a constant velocity\[v={{v}_{0}}\hat{i}.\]The emf induced in the loop is: |
| A. | zero |
| B. | \[{{v}_{0}}{{B}_{0}}d\] |
| C. | \[\frac{{{v}_{0}}{{B}_{0}}{{d}^{3}}}{{{a}^{2}}}\] |
| D. | \[\frac{{{v}_{0}}{{B}_{0}}{{d}^{2}}}{a}\] |
| Answer» E. | |
| 2680. |
A rectangular coil has a long straight wire passing through its centroid perpendicular to its plane as shown. If current through the wire varies as \[i={{i}_{0}}\sin \omega t\], induced current in the coil will be (Given R = Resistance of the coil) |
| A. | \[\frac{{{i}_{0}}\sin \omega t}{R}\] |
| B. | \[\frac{\pi a\sin \omega t}{bR}\] |
| C. | zero |
| D. | \[\frac{\pi a\cos \omega t}{bR}\] |
| Answer» D. \[\frac{\pi a\cos \omega t}{bR}\] | |
| 2681. |
Charge Q is uniformly distributed on a thin insulating ring of mass m which is initially at rest. To what angular velocity will the ring be accelerated when a magnetic field B, perpendicular to the plane of the ring, is switched on? |
| A. | \[\frac{QB}{2m}\] |
| B. | \[\frac{3QB}{2m}\] |
| C. | \[\frac{QB}{m}\] |
| D. | \[\frac{QB}{4m}\] |
| Answer» B. \[\frac{3QB}{2m}\] | |
| 2682. |
A flexible wire loop in the shape of a circle has radius that grown linearly with time. There is a magnetic field perpendicular to the plane of the loop that has a magnitude inversely proportional to the distance from the center of the loop, \[B(r)\propto \frac{1}{r}\].How does the emf E vary with time? |
| A. | \[E\propto {{t}^{2}}\] |
| B. | \[E\propto t\] |
| C. | \[E\propto \sqrt{t}\] |
| D. | E is constant |
| Answer» E. | |
| 2683. |
A rectangular loop is present in the magnetic field region of an infinite long wire. Now the loop is being rotated as shown in the figure. Then the induced current in side AD will be |
| A. | along DA |
| B. | along AD |
| C. | zero |
| D. | None of these |
| Answer» B. along AD | |
| 2684. |
The radius of the circular conducting loop shown in fig. is R. Magnetic field is decreasing at a constant rate a. Resistance per unit length of the loop is \[\rho \]. Then, the current in wire AB is (AB is one of the diameters) |
| A. | \[\frac{R\alpha }{2\rho }\]from A to B |
| B. | \[\frac{R\alpha }{2\rho }\] from B to A |
| C. | \[\frac{R\alpha }{2\rho }\] from A to B |
| D. | 0 |
| Answer» E. | |
| 2685. |
A coil of circular cross-section having 1000 turns and\[4\,c{{m}^{2}}\] face area is placed with its axis parallel to a magnetic field which decreases by\[{{10}^{-2}}\,Wb\,\,{{m}^{-2}}\] in 0.01 s. The e.m.f. induced in the coil is: |
| A. | 400mV |
| B. | 200mV |
| C. | 4mV |
| D. | 0.4mV |
| Answer» B. 200mV | |
| 2686. |
A square loop with 2.0 m sides is perpendicular to a uniform magnetic field, with half the area of the loop in the field is shown in figure. The loop contains a 20.0 V battery with negligible internal resistance. If the magnitude of the field varies with time according to B = 0.042-0.871, with B in tesia and t in second. The net emf of the circuit is: |
| A. | \[20.0\,V\] |
| B. | \[18.26\,V\] |
| C. | \[21.74\,V\] |
| D. | None of these |
| Answer» D. None of these | |
| 2687. |
In a uniform and constant magnetic field of induction B, two long conducting wires ab and cd are kept parallel to each other at distance \[\ell \] with their plane perpendicular to B. The ends a and c are connected together by an ideal inductor of inductance L. A conducting slider wire PQ is imparted a speed \[{{v}_{0}}\] at time t=0. The situation is shown in the figure. At time\[t=\frac{\pi \sqrt{ML}}{4\,B\ell }\], the value of current \[I\] through the wire PQ is (ignore any resistance, electrical as well as mechanical) |
| A. | \[\sqrt{\frac{mv_{0}^{2}}{L}}\] |
| B. | \[\sqrt{\frac{mv_{0}^{2}}{2L}}\] |
| C. | \[\sqrt{\frac{mv_{0}^{2}}{4L}}\] |
| D. | zero |
| Answer» C. \[\sqrt{\frac{mv_{0}^{2}}{4L}}\] | |
| 2688. |
A conducting circular loop is placed in a uniform magnetic field of 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. The induced emf in the loop when the radius is 2 cm is |
| A. | \[4.8\pi \mu \,V\] |
| B. | \[0.8\pi \mu \,V\] |
| C. | \[1.6\pi \mu \,V\] |
| D. | \[3.2\pi \mu \,V\] |
| Answer» E. | |
| 2689. |
Magnetic flux linked with a stationary loop of resistance R varies with respect to time during the time period T as follows: \[\phi =at(T-t)\] The amount of heat generated in the loop during that time (inductance of the coil is negligible) is |
| A. | \[\frac{aT}{3R}\] |
| B. | \[\frac{{{a}^{2}}{{T}^{2}}}{3R}\] |
| C. | \[\frac{{{a}^{2}}{{T}^{2}}}{R}\] |
| D. | \[\frac{{{a}^{2}}{{T}^{3}}}{3R}\] |
| Answer» E. | |
| 2690. |
A rod OA of length \[l\] is rotating (about end 0) over a conducting ring in crossed magnetic field B with constant angular velocity co as shown in figure |
| A. | Current flowing through the rod is\[\frac{B\omega \,{{l}^{2}}}{R}\] |
| B. | Magnetic force acting on the rod is \[\frac{3{{B}^{2}}\omega \,{{l}^{3}}}{4R}\] |
| C. | Torque due to magnetic force acting on the rod is\[\frac{3{{B}^{2}}\omega \,{{l}^{4}}}{8R}\] |
| D. | Magnitude of external force that acts perpendicularly at the end of the rod to maintain the constant angular speed is \[\frac{3{{B}^{2}}\omega \,{{l}^{3}}}{5R}\]. |
| Answer» D. Magnitude of external force that acts perpendicularly at the end of the rod to maintain the constant angular speed is \[\frac{3{{B}^{2}}\omega \,{{l}^{3}}}{5R}\]. | |
| 2691. |
Fig shown below represents an area \[A=0.5\,{{m}^{2}}\] situated in a uniform magnetic field \[B=2.0\,weber/{{m}^{2}}\] and making an angle of \[60{}^\circ \] with respect to magnetic field. The value of the magnetic flux through the area would be equal to |
| A. | 2.0 weber |
| B. | \[\sqrt{3}\text{ }weber~~~\] |
| C. | \[\sqrt{3}\text{/2 }weber\] |
| D. | 0.5 weber |
| Answer» E. | |
| 2692. |
The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward towards the center of the Earth. This gives the total net surface charge carried by the Earth to be: [Given \[{{\varepsilon }_{0}}=8.85\times {{10}^{-12}}{{C}^{2}}/N-{{m}^{2}},\]\[{{R}_{E}}=\]\[6.37\times {{10}^{6}}m\]] magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward |
| A. | +670kC |
| B. | -670kC |
| C. | -680kC |
| D. | +680kC |
| Answer» D. +680kC | |
| 2693. |
The surface density on the copper sphere is \[\sigma .\]The electric field strength on the surface of the sphere is |
| A. | \[\sigma \] |
| B. | \[\sigma \,/2\] |
| C. | \[\sigma \,/2{{\varepsilon }_{0}}\] |
| D. | \[Q/{{\varepsilon }_{0}}\] |
| Answer» E. | |
| 2694. |
A charge q is placed at the center of the open end of a cylindrical vessel. The flux of the electric filed through the surface of the vessel is |
| A. | zero |
| B. | \[q/{{\varepsilon }_{0}}\] |
| C. | \[q/2{{\varepsilon }_{0}}\] |
| D. | \[2q/{{\varepsilon }_{0}}\] |
| Answer» B. \[q/{{\varepsilon }_{0}}\] | |
| 2695. |
For a given surface the Gauss's law is stated as \[\oint{\vec{E}.dA=0.}\]From this we can conclude that |
| A. | E is necessarily zero on the surface |
| B. | E is perpendicular to the surface at every point |
| C. | the total flux through the surface is zero |
| D. | the flux is only going out of the surface |
| Answer» D. the flux is only going out of the surface | |
| 2696. |
Flux passing through the shaded surface of a sphere when point charge q is placed when a point charge q is placed at the center is (radius of the sphere is R) |
| A. | \[q/{{\varepsilon }_{0}}\] |
| B. | \[q/2{{\varepsilon }_{0}}\] |
| C. | \[q/4{{\varepsilon }_{0}}\] |
| D. | zero |
| Answer» D. zero | |
| 2697. |
A uniformly charged and infinitely long line having a linear charge density \[\lambda \] is placed at a normal distance y from a point O. Consider an imaginary sphere of radius R with O as center and R>y. Electric flux through the surface of the sphere is |
| A. | zero |
| B. | \[\frac{2\lambda R}{{{\varepsilon }_{0}}}\] |
| C. | \[\frac{2\lambda \sqrt{{{R}^{2}}-{{y}^{2}}}}{{{\varepsilon }_{0}}}\] |
| D. | \[\frac{\lambda \sqrt{{{R}^{2}}+{{y}^{2}}}}{{{\varepsilon }_{0}}}\] |
| Answer» D. \[\frac{\lambda \sqrt{{{R}^{2}}+{{y}^{2}}}}{{{\varepsilon }_{0}}}\] | |
| 2698. |
Figure shows a uniformly charged hemisphere of radius R. It has a volume charge density \[\rho .\] If the electric field at a point 2R, above its center is E, then what is the electric field at the point 2R below its center? |
| A. | \[\rho R/6{{\varepsilon }_{0}}+E\] |
| B. | \[\rho R/12{{\varepsilon }_{0}}-E\] |
| C. | \[-\rho R/6{{\varepsilon }_{0}}+E\] |
| D. | \[\rho R/12{{\varepsilon }_{0}}+E\] |
| Answer» C. \[-\rho R/6{{\varepsilon }_{0}}+E\] | |
| 2699. |
Three charges +q, +2q and +4q are connected by string as shown in the figure. What is ration of tension in the strings AB and BC? |
| A. | 1 : 2 |
| B. | 1 : 3 |
| C. | 2 : 1 |
| D. | 3 : 1 |
| Answer» C. 2 : 1 | |
| 2700. |
A charged particle q is placed at the center O of cube of length L (A B C D E F G H). Another same charge q is place at a distance L from O. Then the electric flux through ABCD is |
| A. | \[q/4\pi {{\in }_{0}}L\] |
| B. | zero |
| C. | \[q/2\pi {{\in }_{0}}L\] |
| D. | \[q/3\pi {{\in }_{0}}L\] |
| Answer» C. \[q/2\pi {{\in }_{0}}L\] | |