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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.
| 251. |
Which impurity is doped in Si to form N-type semi-conductor? [CBSE PMT 1996; AIEEE 2002] |
| A. | Al |
| B. | B |
| C. | As |
| D. | None of these |
| Answer» D. None of these | |
| 252. |
In Young's experiment, the distance between slits is 0.28 mm and distance between slits and screen is 1.4 m. Distance between central bright fringe and third bright fringe is 0.9 cm. What is the wavelength of used light [KCET 1999] |
| A. | \[5000\,\,{AA}\] |
| B. | \[6000\,\,{AA}\] |
| C. | \[7000\,\,{AA}\] |
| D. | \[9000\,\,{AA}\] |
| Answer» C. \[7000\,\,{AA}\] | |
| 253. |
Two parallel slits 0.6 mm apart are illuminated by light source of wavelength 6000 Å. The distance between two consecutive dark fringes on a screen 1 m away from the slits is [JIPMER 1999] |
| A. | 1 mm |
| B. | 0.01 mm |
| C. | 0.1 m |
| D. | 10 m |
| Answer» B. 0.01 mm | |
| 254. |
A big drop of radius R is formed by 1000 small droplets of water, then the radius of small drop is [AFMC 1998; Pb. PMT 2000] |
| A. | R/2 |
| B. | R/5 |
| C. | R/6 |
| D. | R/10 |
| Answer» E. | |
| 255. |
When \[{{10}^{6}}\]small drops coalesce to make a new larger drop then the drop [RPMT 1999] |
| A. | Density increases |
| B. | Density decreases |
| C. | Temperature increases |
| D. | Temperature decreases |
| Answer» D. Temperature decreases | |
| 256. |
Wave nature of light is verified by [RPET 2001] |
| A. | Interference |
| B. | Photoelectric effect |
| C. | Reflection |
| D. | Refraction |
| Answer» B. Photoelectric effect | |
| 257. |
Two waves are represented by the equations \[{{y}_{1}}=a\sin \omega t\] and \[{{y}_{2}}=a\cos \omega t.\] The first wave [MP PMT 2001] |
| A. | Leads the second by p |
| B. | Lags the second by p |
| C. | Leads the second by \[\frac{\pi }{2}\] |
| D. | Lags the second by \[\frac{\pi }{2}\] |
| Answer» E. | |
| 258. |
Light waves producing interference have their amplitudes in the ratio 3 : 2. The intensity ratio of maximum and minimum of interference fringes is [EAMCET 2001] |
| A. | 36 : 1 |
| B. | 9 : 4 |
| C. | 25 : 1 |
| D. | 6 : 4 |
| Answer» D. 6 : 4 | |
| 259. |
If the differential equation for a simple harmonic motion is \[\frac{{{d}^{2}}{{y}^{2}}}{d{{t}^{2}}}+2y=0\], the time-period of the motion is |
| A. | \[\pi \sqrt{2}s\] |
| B. | \[\frac{\sqrt{2}s}{\pi }\] |
| C. | \[\frac{\pi }{\sqrt{2}}\] |
| D. | \[2\pi s\] |
| Answer» B. \[\frac{\sqrt{2}s}{\pi }\] | |
| 260. |
Masses \[{{M}_{A}}\] and \[{{M}_{B}}\] hanging from the ends of strings of lengths \[{{L}_{A}}\] and \[{{L}_{B}}\] are executing simple harmonic- motions. If their frequencies are \[{{f}_{A}}=2{{f}_{B}}\], then |
| A. | \[{{L}_{A}}=2{{L}_{B}}\,and\,{{M}_{A}}={{M}_{B}}/2\] |
| B. | \[{{L}_{A}}=4{{L}_{B}}\] regardless of masses |
| C. | \[{{L}_{A}}={{L}_{B}}/4\] regardless of masses |
| D. | \[{{L}_{A}}=2{{L}_{B}}\,\,\,and\,{{M}_{A}}=2{{M}_{B}}\] |
| Answer» D. \[{{L}_{A}}=2{{L}_{B}}\,\,\,and\,{{M}_{A}}=2{{M}_{B}}\] | |
| 261. |
A point object is kept in front of a plane mirror. The plane mirror is doing SHM of amplitude 2 cm. The plane mirror moves along the x - axis which is normal to the mirror. The amplitude of the mirror is such that the object is always in front of the mirror. The amplitude of SHM of the image is |
| A. | 0 |
| B. | 2 cm |
| C. | 4 cm |
| D. | 1 cm |
| Answer» D. 1 cm | |
| 262. |
The band gap in Germanium and silicon in eV respectively is [MP PMT 2001] |
| A. | 0.7, 1.1 |
| B. | 1.1, 0.7 |
| C. | 1.1, 0 |
| D. | 0, 1.1 |
| Answer» B. 1.1, 0.7 | |
| 263. |
The unit of self inductance of a coil is [MP PMT 1983, 92; SCRA 1986; CBSE PMT 1993; CPMT 1984, 85, 87] |
| A. | Farad |
| B. | Henry |
| C. | Weber |
| D. | Tesla |
| Answer» C. Weber | |
| 264. |
Two pieces of glass plate one upon the other with a little water in between them cannot be separated easily because of [JIPMER 1997] |
| A. | Inertia |
| B. | Pressure |
| C. | Surface tension |
| D. | Viscosity |
| Answer» D. Viscosity | |
| 265. |
A ray parallel to principal axis is incident at \[30{}^\circ \]from normal on concave mirror having radius of curvature R. The point on principal axis where rays are focused is Q such that PQ is |
| A. | \[\frac{R}{2}\] |
| B. | \[\frac{R}{\sqrt{3}}\] |
| C. | \[\frac{2\sqrt{R}-\sqrt{R}}{\sqrt{2}}\] |
| D. | \[R\left( 1-\frac{1}{\sqrt{3}} \right)\] |
| Answer» E. | |
| 266. |
Three identical rods are hinged at point A as shown. The angle made by rod AB with vertical is |
| A. | \[{{\tan }^{-1}}\left( \frac{1}{\sqrt{3}} \right)\] |
| B. | \[{{\tan }^{-1}}\left( \frac{3}{4} \right)\] |
| C. | \[{{\tan }^{-1}}\left( 1 \right)\] |
| D. | \[{{\tan }^{-1}}\left( \frac{4}{3} \right)\] |
| Answer» C. \[{{\tan }^{-1}}\left( 1 \right)\] | |
| 267. |
If a spring extends by x on loading, then the energy stored by the spring is (if T is tension in the spring and k is spring constant) [AIIMS 1997] |
| A. | \[\frac{{{T}^{2}}}{2x}\] |
| B. | \[\frac{{{T}^{2}}}{2k}\] |
| C. | \[\frac{2x}{{{T}^{2}}}\] |
| D. | \[\frac{2{{T}^{2}}}{k}\] |
| Answer» C. \[\frac{2x}{{{T}^{2}}}\] | |
| 268. |
\[[ML{{T}^{-1}}]+[ML{{T}^{-1}}]=..........\] |
| A. | \[[{{M}^{o}}{{L}^{o}}{{T}^{o}}]\] |
| B. | \[[ML{{T}^{-1}}]\] |
| C. | \[2[ML{{T}^{-1}}]\] |
| D. | None of these |
| Answer» C. \[2[ML{{T}^{-1}}]\] | |
| 269. |
Assertion : The size of the mirror affect the nature of the image. Reason : Small mirrors always forms a virtual image. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» E. If assertion is false but reason is true. | |
| 270. |
Assertion : Just before setting, the sun may appear to be elliptical. This happens due to refraction. Reason : Refraction of light ray through the atmosphere may cause different magnification in mutually perpendicular directions. |
| 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. | If assertion is true but reason is false. |
| 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. | |
| 271. |
Assertion : Critical angle of light passing from glass to air is minimum for violet colour. Reason : The wavelength of blue light is greater than the light of other colours. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» D. If the assertion and reason both are false. | |
| 272. |
In the Young's double slit experiment, the spacing between two slits is 0.1 mm. If the screen is kept at a distance of 1.0 m from the slits and the wavelength of light is 5000 Å, then the fringe width is [MP PMT 1993; RPET 1996] |
| A. | 1.0 cm |
| B. | 1.5 cm |
| C. | 0.5 cm |
| D. | 2.0 cm |
| Answer» D. 2.0 cm | |
| 273. |
In Young's double slit experiment, if L is the distance between the slits and the screen upon which interference pattern is observed, x is the average distance between the adjacent fringes and d being the slit separation. The wavelength of light is given by [MP PET 1993] |
| A. | \[\frac{xd}{L}\] |
| B. | \[\frac{xL}{d}\] |
| C. | \[\frac{Ld}{x}\] |
| D. | \[\frac{1}{Ldx}\] |
| Answer» B. \[\frac{xL}{d}\] | |
| 274. |
In a Young's double slit experiment, the central point on the screen is [MP PMT 1996] |
| A. | Bright |
| B. | Dark |
| C. | First bright and then dark |
| D. | First dark and then bright |
| Answer» B. Dark | |
| 275. |
The kinetic energy of a body of mass 2 kg and momentum of 2 Ns is [AFMC 1998; DPMT 2000] |
| A. | 1 J |
| B. | 2 J |
| C. | 3 J |
| D. | 4 J |
| Answer» B. 2 J | |
| 276. |
If the nucleus \[_{13}^{27}Al\] has nuclear radius of about 3.6 fm, then \[_{32}^{125}Te\] would have its radius approximately as |
| A. | 9.6 fm |
| B. | 12.0 fm |
| C. | 4.8 fm |
| D. | 6.0 fm. |
| Answer» E. | |
| 277. |
The capacitance of a parallel plate capacitor is \[12\,\mu \,F\]. If the distance between the plates is doubled and area is halved, then new capacitance will be [MH CET 2002] |
| A. | \[8\,\mu \,F\] |
| B. | \[6\,\mu \,F\] |
| C. | \[4\,\mu \,F\] |
| D. | \[3\,\mu \,F\] |
| Answer» E. | |
| 278. |
A toroid has number of turns per unit length n, current i, then the magnetic field is [RPET 2000] |
| A. | \[{{\mu }_{0}}ni\] |
| B. | \[{{\mu }_{0}}{{n}^{2}}i\] |
| C. | \[{{\mu }_{0}}i/n\] |
| D. | None of these |
| Answer» B. \[{{\mu }_{0}}{{n}^{2}}i\] | |
| 279. |
In an atom for the electron to revolve around the nucleus, the necessary centripetal force is obtained from the following force exerted by the nucleus on the electron [MP PET 2002] |
| A. | Nuclear force |
| B. | Gravitational force |
| C. | Magnetic force |
| D. | Electrostatic force |
| Answer» E. | |
| 280. |
The absolute zero is the temperature at which [AIIMS 1998] |
| A. | Water freezes |
| B. | All substances exist in solid state |
| C. | Molecular motion ceases |
| D. | None of the above |
| Answer» D. None of the above | |
| 281. |
Assertion : To empty an oil tank, two holes are made. Reason : Oil will come out two holes so it will emptied faster. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» D. If the assertion and reason both are false. | |
| 282. |
Assertion : Tiny drops of liquid resist deforming forces better than bigger drops. Reason : Excess pressure inside a drop is directly proportional to surface tension. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» C. If assertion is true but reason is false. | |
| 283. |
The moment of inertia of a circular disc of mass and radius R about an axis passing through the centre of mass is\[{{I}_{0}}\]. The moment of inertia of another circular disc of same mass and thickness but half the density about the same axis is |
| A. | \[\frac{{{I}_{0}}}{8}\] |
| B. | \[\frac{{{I}_{0}}}{4}\] |
| C. | \[8{{I}_{0}}\] |
| D. | \[2{{I}_{0}}\] |
| Answer» E. | |
| 284. |
A wire is suspended by one end. At the other end a weight equivalent to 20 N force is applied. If the increase in length is 1.0 mm, the increase in energy of the wire will be |
| A. | 0.01 J |
| B. | 0.02 J |
| C. | 0.04 J |
| D. | 1.00 J |
| Answer» B. 0.02 J | |
| 285. |
Assertion : If a plane glass slab is placed on the letters of different colours all the letters appear to be raised up to the same height. Reason : Different colours have different wavelengths. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» F. | |
| 286. |
A force \[F\] acts between sodium and chlorine ions of salt (sodium chloride) when put \[1\,cm\] apart in air. The permittivity of air and dielectric constant of water are \[{{\varepsilon }_{0}}\] and \[K\] respectively. When a piece of salt is put in water electrical force acting between sodium and chlorine ions \[1\,cm\] apart is [MP PET 1995] |
| A. | \[\frac{F}{K}\] |
| B. | \[\frac{FK}{{{\varepsilon }_{0}}}\] |
| C. | \[\frac{F}{K{{\varepsilon }_{0}}}\] |
| D. | \[\frac{F{{\varepsilon }_{0}}}{K}\] |
| Answer» B. \[\frac{FK}{{{\varepsilon }_{0}}}\] | |
| 287. |
A simple pendulum hangs from the ceiling of a car. If the car accelerates with a uniform acceleration, the frequency of the simple pendulum will [Pb. PMT 2000] |
| A. | Increase |
| B. | Decrease |
| C. | Become infinite |
| D. | Remain constant |
| Answer» B. Decrease | |
| 288. |
Assertion : A physical quantity cannot be called as a vector if its magnitude is zero. Reason : A vector has both, magnitude and direction. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» F. | |
| 289. |
The count rate from a radioactive sample falls from \[4.0\times {{10}^{6}}\] per second to \[1\times {{10}^{6}}\]per second in 20 hour. What will be the count rate, 100 hour after the beginning? |
| A. | \[3.91\times {{10}^{3}}\text{ }se{{c}^{-1}}\] |
| B. | \[5.81\times {{10}^{4}}\text{ }se{{c}^{-1}}\] |
| C. | \[6.22\times {{10}^{5}}\text{ }se{{c}^{-1}}\] |
| D. | None of these |
| Answer» B. \[5.81\times {{10}^{4}}\text{ }se{{c}^{-1}}\] | |
| 290. |
Thermoelectric thermometer is based on [CPMT 1993, 95; AFMC 1998] |
| A. | Photoelectric effect |
| B. | Seeback effect |
| C. | Compton effect |
| D. | Joule effect |
| Answer» C. Compton effect | |
| 291. |
The moment of inertia of the rectangular plate \[ABCD,(AB=2\text{ }BC)\]is minimum along the axis |
| A. | GH |
| B. | EF |
| C. | BC |
| D. | AC |
| Answer» C. BC | |
| 292. |
Stationary waves [Kerala (Med.) 2002] |
| A. | Transport energy |
| B. | Does not transport energy |
| C. | Have nodes and antinodes |
| D. | Both (b) and (c) |
| Answer» E. | |
| 293. |
A cart of mass M has a block of mass m attached to it as shown in fig. The coefficient of friction between the block and the cart is u. What is the minimum acceleration of the cart so that the block m does not fall? |
| A. | \[\mu g\] |
| B. | \[g/\mu \] |
| C. | \[\mu /g\] |
| D. | \[M\mu g\text{/}m\] |
| Answer» C. \[\mu /g\] | |
| 294. |
Assertion : Penetrating power of X-rays increases with the increasing the wavelength. Reason : The penetrating power of X-rays increases with the frequency of X-rays. |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» F. | |
| 295. |
During the nuclear fusion reaction |
| A. | A heavy nucleus breaks into two fragments by itself |
| B. | A light nucleus bombarded by thermal neutrons breaks up |
| C. | A heavy nucleus bombarded by thermal neutrons breaks up |
| D. | Two light nuclei combine to give a heavier nucleus and possibly other products |
| Answer» E. | |
| 296. |
Assertion : Temperatures near the sea coast are moderate. Reason : Water has a high thermal conductivity. [AIIMS 2003] |
| 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. | If assertion is true but reason is false. |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» C. If assertion is true but reason is false. | |
| 297. |
Frequency of a sonometer wire is n. Now its tension is increased 4 times and its length is doubled then new frequency will be [RPET 2000] |
| A. | n/2 |
| B. | 4n |
| C. | 2n |
| D. | n |
| Answer» E. | |
| 298. |
A standing wave having 3 nodes and 2 antinodes is formed between two atoms having a distance 1.21 Å between them. The wavelength of the standing wave is [CBSE PMT 1998; MH CET 2002; AIIMS 2000; BHU 2001] |
| A. | 1.21 Å |
| B. | 2.42 Å |
| C. | 6.05 Å |
| D. | 3.63 Å |
| Answer» B. 2.42 Å | |
| 299. |
If the length of a stretched string is shortened by 40% and the tension increased by 44% then the ratio of the final and initial fundamental frequencies is |
| A. | 3 : 4 |
| B. | 4 : 3 |
| C. | 0.04375 |
| D. | 0.0840277777777778 |
| Answer» E. | |
| 300. |
Given a point source of light, which of the following can produce a parallel beam of light [CPMT 1974; KCET 2005] |
| A. | Convex mirror |
| B. | Concave mirror |
| C. | Concave lens |
| D. | Two plane mirrors inclined at an angle of \[90{}^\circ \] |
| Answer» C. Concave lens | |