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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.
| 2551. |
If the electrostatic potential were given by \[\phi ={{\phi }_{0}}({{x}^{2}}+{{y}^{2}}+{{z}^{2}}),\]where is constant, then the charge density giving rise to the above potential would be. |
| A. | 0 |
| B. | \[-6{{\phi }_{0}}{{\varepsilon }_{0}}\] |
| C. | \[-2{{\phi }_{0}}{{\varepsilon }_{0}}\] |
| D. | \[-\frac{6{{\phi }_{0}}}{{{\varepsilon }_{0}}}\] |
| Answer» C. \[-2{{\phi }_{0}}{{\varepsilon }_{0}}\] | |
| 2552. |
Two equally charged spheres of radii a and b are connected together. What will be the ratio of electric field intensity on their surfaces? |
| A. | \[\frac{a}{b}\] |
| B. | \[\frac{{{a}^{2}}}{{{b}^{2}}}\] |
| C. | \[\frac{b}{a}\] |
| D. | \[\frac{{{b}^{2}}}{{{a}^{2}}}\] |
| Answer» D. \[\frac{{{b}^{2}}}{{{a}^{2}}}\] | |
| 2553. |
A non-conducting ring of radius 0.5 m carries a total charge of \[1.11\times {{10}^{-10}}C\]distributed non-uniformly on its circumference producing an electric field E everywhere in space. The value of the integral \[\int\limits_{\ell =\infty }^{\ell =0}{-E.dl}\] (\[\ell =0\]being center of the ring) in volts is |
| A. | 2 |
| B. | -1 |
| C. | -2 |
| D. | zero |
| Answer» B. -1 | |
| 2554. |
In moving from A to B along an electric field line, the work done by the electric field on an electron is \[6.4\times {{10}^{-19}}J.\] If \[{{\phi }_{1}}\] and \[{{\phi }_{2}}\]are equipotential surfaces, then the potential difference \[{{V}_{C}}-{{V}_{A}}\] is |
| A. | -4V |
| B. | 4V |
| C. | zero |
| D. | 6.4V |
| Answer» C. zero | |
| 2555. |
A cube of a metal is given a positive charge Q. For this system, which of the following statements is true? |
| A. | Electric potential at the surface of the cube |
| B. | Electric potential within the cube is zero |
| C. | Electric field is normal to the surface of the cube |
| D. | Electric field varies within the cube |
| Answer» E. | |
| 2556. |
A unit charge moves on an equipotential surface from a point A to point B, then |
| A. | \[{{V}_{A}}-{{V}_{B}}=+\,ve\] |
| B. | \[{{V}_{A}}-{{V}_{B}}=0\] |
| C. | \[{{V}_{A}}-{{V}_{B}}=-\,ve\] |
| D. | it is stationary |
| Answer» C. \[{{V}_{A}}-{{V}_{B}}=-\,ve\] | |
| 2557. |
A unit positive point charge of mass m is projected with a velocity V inside the tunnel as tunnel as shown. The tunnel has been made inside a uniformly charged nonconducting sphere (charge density\[\rho \]). The minimum velocity with which the point charge should be projected such that it can reach the opposite end of the tunnel is equal to |
| A. | \[{{[\rho {{R}^{2}}/4m{{\varepsilon }_{0}}]}^{1/2}}\] |
| B. | \[{{[\rho {{R}^{2}}/24m{{\varepsilon }_{0}}]}^{1/2}}\] |
| C. | \[{{[\rho {{R}^{2}}/6m{{\varepsilon }_{0}}]}^{1/2}}\] |
| D. | zero because the initial and the final points are at some potential |
| Answer» B. \[{{[\rho {{R}^{2}}/24m{{\varepsilon }_{0}}]}^{1/2}}\] | |
| 2558. |
What is the effective capacitance between points X and Y? |
| A. | \[8\mu F\] |
| B. | \[9\mu F\] |
| C. | \[10\mu F\] |
| D. | \[12\mu F\] |
| Answer» B. \[9\mu F\] | |
| 2559. |
A new system of unit is evolved in which the values of \[{{\mu }_{0}}\] and \[{{\in }_{0}}\] are 2 and 8 respectively. Then the speed of light in this system will be |
| A. | \[0.25\] |
| B. | \[0.5\] |
| C. | \[0.75\] |
| D. | \[1\] |
| Answer» B. \[0.5\] | |
| 2560. |
An electromagnetic wave of frequency \[1\times {{10}^{14}}\]hertz is propagating along z-axis. The amplitude of electric field is\[4\text{ }V/m\]. If \[{{\varepsilon }_{0}}=8.8\times {{10}^{-12}}{{C}^{2}}/N-{{m}^{2}},\] then average energy density of electric field will be: |
| A. | \[35.2\times {{10}^{-10}}J/{{m}^{3}}\] |
| B. | \[35.2\times {{10}^{-11}}J/{{m}^{3}}\] |
| C. | \[35.2\times {{10}^{-12}}J/{{m}^{3}}\] |
| D. | \[35.2\times {{10}^{-13}}J/{{m}^{3}}\] |
| Answer» D. \[35.2\times {{10}^{-13}}J/{{m}^{3}}\] | |
| 2561. |
An LC resonant circuit contains a 4 pF capacitor and a 10 mH inductor. It is set into oscillation coupled to an instrument. The wavelength of the radiated electromagnetic waves is: |
| A. | 355 cm |
| B. | 377 m |
| C. | 400 mm |
| D. | 600 mm |
| Answer» C. 400 mm | |
| 2562. |
A plane electromagnetic wave propagating in the X-direction has wavelength of\[6.0\text{ }mm\]. The electric field is in the Y-direction and its maximum magnitude is\[33\text{ }V{{m}^{-1}}\]. The equation for the electric field as a function of x and t is |
| A. | \[11\,\sin \pi \left( t-\frac{x}{c} \right)\] |
| B. | \[33\sin \left[ \pi \times {{10}^{11}}\left( t-\frac{x}{c} \right) \right]\] |
| C. | \[33\sin \,\pi \left( t-\frac{x}{c} \right)\] |
| D. | \[11\sin \,\left[ \pi \times {{10}^{11}}\left( t-\frac{x}{c} \right) \right]\] |
| Answer» C. \[33\sin \,\pi \left( t-\frac{x}{c} \right)\] | |
| 2563. |
A charged particle oscillates about its mean equilibrium position with a frequency of \[{{10}^{9}}\text{ }Hz\]. The electromagnetic waves produced |
| A. | will have frequency of \[{{10}^{6}}\text{ }Hz\] |
| B. | will have frequency of \[2\times {{10}^{3}}\ Hz\] |
| C. | will have wavelength of 0.3 m |
| D. | fall in the region of U.V. waves |
| Answer» D. fall in the region of U.V. waves | |
| 2564. |
The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is |
| A. | \[3V/m\] |
| B. | \[6V/m\] |
| C. | \[9V/m\] |
| D. | \[12V/m\] |
| Answer» C. \[9V/m\] | |
| 2565. |
Which of the following statements is and correct. |
| A. | When variable frequency a.c. Source is connected to a capacitor, displacement current increases with increase in frequency |
| B. | As frequency increases conduction current also increases |
| C. | Short wave bands are used for transmission of radio waves to a large distance |
| D. | Ultraviolet radiation are absorbed by the atmosphere and converts Ozone to Oxygen |
| Answer» E. | |
| 2566. |
During the propagation of electromagnetic waves in a medium |
| A. | electric energy density is double of the magnetic energy density. |
| B. | electric energy density is half of the magnetic energy density. |
| C. | electric energy density is equal to the magnetic energy density |
| D. | both electric and magnetic energy densities are zero. |
| Answer» D. both electric and magnetic energy densities are zero. | |
| 2567. |
Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists: Column I Column II [a] Infrared waves (i) To treat muscular strain [b] Radio waves (ii) For broadcasting [c] X-rays (iii) To detect fracture of bones [d] Ultraviolet rays (iv) Absorbed by the ozone layer of the atmosphere |
| A. | 1-(iv) 2-(iii) 3-(ii) 4-(i) |
| B. | 1-(i) 2-(ii) 3-(iv) 4-(iii) |
| C. | 1-(iii) 2-(ii) 3-(i) 4-(iv) |
| D. | 1-(i) 2-(ii) 3-(iii) 4-(iv) |
| Answer» E. | |
| 2568. |
Arrange the following electromagnetic radiations per quantum in the order of increasing energy: A: Blue light B: Yellow light C: X-ray D: Radio wave. |
| A. | C, A, B, D |
| B. | B, A, D, C |
| C. | D, B, A, C |
| D. | A, B, D, C |
| Answer» D. A, B, D, C | |
| 2569. |
The energy contained in a cylinder of cross- section\[10c{{m}^{2}}\]and length 50cm along the x-axis if electric field in an electromagnetic wave is given by \[E=50\,\sin \,\omega (t-x/c)\] is |
| A. | \[1.2\times {{10}^{-10}}\,J\] |
| B. | \[5.5\times {{10}^{-12}}\,J\] |
| C. | \[2.3\times {{10}^{-10}}\,J\] |
| D. | \[3.6\times {{10}^{-12}}\,J\] |
| Answer» C. \[2.3\times {{10}^{-10}}\,J\] | |
| 2570. |
For plane electromagnetic waves propagating in the z-direction, which one of the following combination gives the correct possible direction for \[\vec{E}\] and \[\vec{B}\] field respectively? |
| A. | \[(2\hat{i}+3\hat{j})\] and \[(\hat{i}+2\hat{j})\] |
| B. | \[(-2\hat{i}-3\hat{j})\] and \[(3\hat{i}-2\hat{j})\] |
| C. | \[(3\hat{i}+4\hat{j})\] and \[(4\hat{i}-3\hat{j})\] |
| D. | \[(\hat{i}+2\hat{j})\] and \[(2\hat{i}-\hat{j})\] |
| Answer» C. \[(3\hat{i}+4\hat{j})\] and \[(4\hat{i}-3\hat{j})\] | |
| 2571. |
Which of the following is the infrared ray wavelength? |
| A. | \[{{10}^{-4}}\,cm\] |
| B. | \[{{10}^{-5}}\,cm\] |
| C. | \[{{10}^{-6}}\,cm\] |
| D. | \[{{10}^{-7}}\,cm\] |
| Answer» B. \[{{10}^{-5}}\,cm\] | |
| 2572. |
The magnetic field of a beam emerging from a filter facing a floodlight is given by \[{{B}_{0}}=12\times {{10}^{-8}}\,\sin \,(1.20\times {{10}^{7}}z-3.60\times {{10}^{15}}t)T\]. What is the average intensity of the beam? |
| A. | \[1.72\times {{10}^{2}}\,W/{{m}^{2}}\] |
| B. | \[1.72\,W/{{m}^{2}}\] |
| C. | \[2.31\,W/{{m}^{2}}\] |
| D. | \[2.31\,\times {{10}^{2}}W/{{m}^{2}}\] |
| Answer» C. \[2.31\,W/{{m}^{2}}\] | |
| 2573. |
A parallel plate capacitor with a and separation d, is charged by a constant current I. Consider a plane surface of area\[\frac{a}{2}\]parallel to the plates and drawn symmetrically between the plates. What is the displacement current through this area? |
| A. | \[I/2\] |
| B. | \[I/3\] |
| C. | \[I/5\] |
| D. | \[I/7\] |
| Answer» B. \[I/3\] | |
| 2574. |
Beyond which frequency, the ionosphere bends any incident E.M. radiation but do not reflect it back towards the earth. |
| A. | 80 MHz |
| B. | 40 MHz |
| C. | 20 MHz |
| D. | 10 MHz |
| Answer» C. 20 MHz | |
| 2575. |
Radio waves and visible light in vacuum have |
| A. | same velocity but different wavelength |
| B. | continuous emission spectrum |
| C. | band absorption spectrum |
| D. | line emission spectrum |
| Answer» B. continuous emission spectrum | |
| 2576. |
If microwaves, X rays, infrared, gamma rays, ultra-violet, radio waves and visible parts of the electromagnetic spectrum are denoted by M, X, I, G, U, R and V then which of the following is the arrangement in ascending order of wavelength? |
| A. | R, M, I, V, U, X and G |
| B. | M, R, V, X, U, G and I |
| C. | G, X, U, V, I, M and R |
| D. | I, M, R, U, V, X and G |
| Answer» D. I, M, R, U, V, X and G | |
| 2577. |
Microwave oven acts on the principle of: |
| A. | giving rotational energy to water molecules |
| B. | giving translational energy to water molecules |
| C. | giving vibrational energy to water molecules |
| D. | transferring electrons from lower to higher energy levels in water molecule |
| Answer» D. transferring electrons from lower to higher energy levels in water molecule | |
| 2578. |
Which of the following waves have the maximum wavelength |
| A. | X-rays |
| B. | I.R. rays |
| C. | UV rays |
| D. | Radio waves |
| Answer» E. | |
| 2579. |
Which of the following is the correct equation for magnetic field as a function of x, and t where a plane electromagnetic wave propagating in the x-direction has a wavelength of 5.0 mm? The electric field is in the y-direction and its maximum value is \[30\,V{{m}^{-1}}\]. |
| A. | \[B={{10}^{-3}}\,\sin \,\left[ \frac{2\pi }{5\times {{10}^{-3}}}(ct-x) \right]\] |
| B. | \[B={{10}^{-7}}\,\sin \,\left[ \frac{2\pi }{5\times {{10}^{-3}}}(ct-x) \right]\] |
| C. | \[B={{10}^{-5}}\,\sin \,\left[ \frac{\pi }{1.5\times {{10}^{-3}}}(ct-x) \right]\] |
| D. | None of these |
| Answer» C. \[B={{10}^{-5}}\,\sin \,\left[ \frac{\pi }{1.5\times {{10}^{-3}}}(ct-x) \right]\] | |
| 2580. |
Find the average energy density corresponding to maximum electric field, if magnetic field in a plane electromagnetic wave is given by \[B=200\times {{10}^{-6}}\,\sin \,[(4\times {{10}^{15}})(t-x/c)]\] |
| A. | \[1.6\,J\,{{m}^{-3}}\] |
| B. | \[0.16\,J\,{{m}^{-3}}\] |
| C. | \[0.016\,J\,{{m}^{-3}}\] |
| D. | \[0.0016\,J\,{{m}^{-3}}\] |
| Answer» D. \[0.0016\,J\,{{m}^{-3}}\] | |
| 2581. |
The amplitude of the electric field if the intensity of a plane electromagnetic wave is given as \[2.0\,W{{m}^{-2}}\] is |
| A. | \[38.8\,N{{C}^{-1}}\] |
| B. | \[48.3\,N{{C}^{-1}}\] |
| C. | \[50.2\,N{{C}^{-1}}\] |
| D. | \[68.8\,N{{C}^{-1}}\] |
| Answer» B. \[48.3\,N{{C}^{-1}}\] | |
| 2582. |
A capacitor, made of two parallel plates each of plate area A and separation d, is being charged by an external ac source. If \[{{I}_{1}}\] and \[{{I}_{2}}\] be the dis- placement current inside the capacitor and the instantaneous current charging the capacitor, then |
| A. | \[{{I}_{1}}={{I}_{2}}\] |
| B. | \[{{I}_{1}}>{{I}_{2}}\] |
| C. | \[{{I}_{1}}<{{I}_{2}}\] |
| D. | None of these |
| Answer» B. \[{{I}_{1}}>{{I}_{2}}\] | |
| 2583. |
An EM wave radiates outwards from a dipole antenna, with \[{{E}_{0}}\] as the amplitude of its electric field vector. The electric field \[{{E}_{0}}\] which transports significant energy from the source falls off as [r = distance from dipole antenna] |
| A. | \[\frac{1}{{{r}^{3}}}\] |
| B. | \[\frac{1}{{{r}^{2}}}\] |
| C. | \[\frac{1}{r}\] |
| D. | remains constant |
| Answer» D. remains constant | |
| 2584. |
Which radiation in sunlight, causes heating effect? |
| A. | Ultraviolet |
| B. | Infrared |
| C. | Visible light |
| D. | All of these |
| Answer» C. Visible light | |
| 2585. |
Which of the following shows greenhouse effect? |
| A. | Ultraviolet rays |
| B. | Infrared rays |
| C. | X-rays |
| D. | None of these |
| Answer» C. X-rays | |
| 2586. |
Given below is a list of E.M spectrum and its use. Which one does not match? |
| A. | U.V. rays - finger prints detection |
| B. | I.R. rays - Secret writing on ancient walls |
| C. | X- rays - Atomic structure |
| D. | Microwaves - forged document detection |
| Answer» E. | |
| 2587. |
The range of wavelength of the visible light is |
| A. | \[10\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,100\overset{o}{\mathop{A}}\,\] |
| B. | \[4,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,\,8,000\overset{o}{\mathop{A}}\,\] |
| C. | \[8,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,10,000\overset{o}{\mathop{A}}\,\] |
| D. | \[10,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,15,000\overset{o}{\mathop{A}}\,\] |
| Answer» C. \[8,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,10,000\overset{o}{\mathop{A}}\,\] | |
| 2588. |
All components of the electromagnetic spectrum in vacuum have the same |
| A. | energy |
| B. | velocity |
| C. | wavelength |
| D. | frequency |
| Answer» C. wavelength | |
| 2589. |
A circular ring of radius r is placed in a homogeneous magnetic field perpendicular to the plane of the ring. The field B changes with time according to equation \[B=kt,\]where, k is a constant and t is the time). The electric field in the ring is: |
| A. | \[\frac{kr}{4}\] |
| B. | \[\frac{kr}{3}\] |
| C. | \[\frac{kr}{2}\] |
| D. | \[\frac{k}{2r}\] |
| Answer» D. \[\frac{k}{2r}\] | |
| 2590. |
Which of the following electromagnetic waves has minimum frequency? |
| A. | Microwaves |
| B. | Audible waves |
| C. | Ultrasonic wave |
| D. | Radio waves |
| Answer» C. Ultrasonic wave | |
| 2591. |
In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption? |
| A. | Ultraviolet |
| B. | Microwaves |
| C. | Infrared |
| D. | Radio waves |
| Answer» C. Infrared | |
| 2592. |
We consider the radiation emitted by the human body. Which of the following statements is true? |
| A. | the radiation emitted lies in the ultraviolet region and hence is not visible. |
| B. | the radiation emitted is in the infra-red region. |
| C. | the radiation is emitted only during the day. |
| D. | the radiation is emitted during the summers and absorbed during the winters. |
| Answer» C. the radiation is emitted only during the day. | |
| 2593. |
Electromagnetic radiation of highest frequency is |
| A. | infrared radiations |
| B. | visible radiation |
| C. | radio waves |
| D. | \[\gamma -rays\] |
| Answer» E. | |
| 2594. |
An electromagnetic radiation has an energy 11 keV. To which region of electromagnetic spectrum does it belong? |
| A. | X-ray region |
| B. | Ultra violet region |
| C. | Infrared region |
| D. | Visible region |
| Answer» B. Ultra violet region | |
| 2595. |
The energy density of electromagnetic wave in vacuum is given by the relation |
| A. | \[\frac{{{E}^{2}}}{2{{\varepsilon }_{0}}}+\frac{{{B}^{2}}}{2{{\mu }_{0}}}\] |
| B. | \[\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}+\frac{1}{2}{{\mu }_{0}}{{B}^{2}}\] |
| C. | \[\frac{{{E}^{2}}+{{B}^{2}}}{c}\] |
| D. | \[\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}+\frac{{{B}^{2}}}{2{{\mu }_{0}}}\] |
| Answer» E. | |
| 2596. |
Which of the following has/have zero average value in a plane electromagnetic wave? |
| A. | Both magnetic and electric fields |
| B. | Electric field only |
| C. | Magnetic field only |
| D. | Magnetic energy |
| Answer» B. Electric field only | |
| 2597. |
In an electromagnetic wave, power is |
| A. | transmitted along the magnetic field |
| B. | transmitted along the electric field equally |
| C. | transferred along the electric and magnetic fields |
| D. | transmitted in a direction perpendicular to both electric and magnetic fields |
| Answer» E. | |
| 2598. |
The electric field component of a monochromatic radiation is given by \[\vec{E}=2{{E}_{0}}\,\,\hat{i}\,\,\cos \,\,kz\,\cos \omega t\] Its magnetic field B is then given by: |
| A. | \[\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\cos \,\omega t\] |
| B. | \[-\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\sin \,\omega t\] |
| C. | \[\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\sin \,\omega t\] |
| D. | \[\frac{2{{E}_{o}}}{c}\hat{j}\,\cos \,kz\,\cos \,\omega t\] |
| Answer» D. \[\frac{2{{E}_{o}}}{c}\hat{j}\,\cos \,kz\,\cos \,\omega t\] | |
| 2599. |
In an apparatus, the electric field was found to oscillate with an amplitude of\[24\text{ }V/m\]. The magnitude of the oscillating magnetic field will be |
| A. | \[6\times {{10}^{-6}}T\] |
| B. | \[2\times {{10}^{-8}}T\] |
| C. | \[8\times {{10}^{-8}}T\] |
| D. | \[12\times {{10}^{-6}}T\] |
| Answer» D. \[12\times {{10}^{-6}}T\] | |
| 2600. |
In order to establish an instantaneous displacemet current of \[1\text{ }mA\] in the space between the plates of \[2\mu F\] parallel plate capacitor, the potential difference need to apply is |
| A. | \[100\,\,V{{s}^{-1}}\] |
| B. | \[200\,\,V{{s}^{-1}}\] |
| C. | \[300\,\,V{{s}^{-1}}\] |
| D. | \[500\,\,V{{s}^{-1}}\] |
| Answer» E. | |