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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.
| 1. |
Find the equivalent thermal resistance of combination of rods as shown in figure. Every rod has same length I and cross-sectional area A. Thermal conductivities are mentioned in figure. |
| A. | \[\frac{1}{4KA}\] |
| B. | \[\frac{7l}{4KA}\] |
| C. | \[\frac{7l}{12KA}\] |
| D. | \[\frac{l}{12KA}\] |
| Answer» D. \[\frac{l}{12KA}\] | |
| 2. |
The ripple factor in a half wave rectifier is [RPMT 2002] |
| A. | 1.21 |
| B. | 0.48 |
| C. | 0.6 |
| D. | None of these |
| Answer» B. 0.48 | |
| 3. |
Assertion : Two persons on the surface of moon cannot talk to each other. Reason : There is no atmosphere on moon. |
| 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. | |
| 4. |
A potential barrier of 0.50 V exists across a P-N junction. If the depletion region is \[5.0\times {{10}^{-7}}\]m wide, the intensity of the electric field in this region is [UPSEAT 2002] |
| A. | \[1.0\times {{10}^{6}}\,V/m\] |
| B. | \[1.0\times {{10}^{5}}\,V/m\] |
| C. | \[2.0\times {{10}^{5}}\,V/m\] |
| D. | \[2.0\times {{10}^{6}}\,V/m\] |
| Answer» B. \[1.0\times {{10}^{5}}\,V/m\] | |
| 5. |
The laptop PC?s modern electronic watches and calculators use the following for display |
| A. | Single crystal |
| B. | Poly crystal |
| C. | Liquid crystal |
| D. | Semiconductors |
| Answer» D. Semiconductors | |
| 6. |
The reason of current flow in P-N junction in forward bias is [RPMT 2000] |
| A. | Drifting of charge carriers |
| B. | Minority charge carriers |
| C. | Diffusion of charge carriers |
| D. | All of these |
| Answer» D. All of these | |
| 7. |
The period of a simple pendulum is doubled, when [CPMT 1974; MNR 1980; AFMC 1995; Pb. PET/PMT 2002] |
| A. | Its length is doubled |
| B. | The mass of the bob is doubled |
| C. | Its length is made four times |
| D. | The mass of the bob and the length of the pendulum are doubled |
| Answer» D. The mass of the bob and the length of the pendulum are doubled | |
| 8. |
The period of oscillation of a simple pendulum of constant length at earth surface is T. Its period inside a mine is [CPMT 1973; DPMT 2001] |
| A. | Greater than T |
| B. | Less than T |
| C. | Equal to T |
| D. | Cannot be compared |
| Answer» B. Less than T | |
| 9. |
Assertion : To protect any instrument from external magnetic field, it is put inside an iron body. Reason : Iron is a magnetic substance. |
| 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. | |
| 10. |
Two travelling waves \[{{y}_{1}}=A\sin [k(x-ct)]\] and\[{{y}_{2}}=A\sin [k(x+ct)]\]are superimposed on string. The distance between adjacent nodes is |
| A. | \[ct/\pi \] |
| B. | \[ct/2\pi \] |
| C. | \[\pi /2k\] |
| D. | \[\pi /k\] |
| Answer» E. | |
| 11. |
A hot body will radiate heat most rapidly if its surface is |
| A. | White & polished |
| B. | White & rough |
| C. | Black & polished |
| D. | Black & rough |
| Answer» E. | |
| 12. |
In which of the following process, convection does not take place primarily |
| A. | Sea and land breeze |
| B. | Boiling of water |
| C. | Warming of glass of bulb due to filament |
| D. | Heating air around a furnace |
| Answer» D. Heating air around a furnace | |
| 13. |
A hot and a cold body are kept in vacuum separated from each other. Which of the following cause decrease in temperature of the hot body |
| A. | Radiation |
| B. | Convection |
| C. | Conduction |
| D. | Temperature remains unchanged |
| Answer» B. Convection | |
| 14. |
In a p-n junction having depletion layer of thickness \[{{10}^{-6}}m\] the potential across it is \[0.1\text{ }V\]. The electric field is |
| A. | \[{{10}^{7}}V/m\] |
| B. | \[{{10}^{-6}}V/m\] |
| C. | \[{{10}^{5}}V/m\] |
| D. | \[{{10}^{-5}}V/m\] |
| Answer» D. \[{{10}^{-5}}V/m\] | |
| 15. |
Two vibrating strings of the same material but lengths L and 2L have radii 2r and r respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length L with frequency n1 and the other with frequency n2. The ratio n1/n2 is given by [IIT-JEE (Screening) 2000] |
| A. | 2 |
| B. | 4 |
| C. | 8 |
| D. | 1 |
| Answer» E. | |
| 16. |
Expansion during heating [CBSE PMT 1994] |
| A. | Occurs only in solids |
| B. | Increases the weight of a material |
| C. | Decreases the density of a material |
| D. | Occurs at the same rate for all liquids and solids |
| Answer» D. Occurs at the same rate for all liquids and solids | |
| 17. |
If the length of simple pendulum is increased by 300%, then the time period will be increased by [RPMT 1999] |
| A. | 100% |
| B. | 200% |
| C. | 300% |
| D. | 400% |
| Answer» B. 200% | |
| 18. |
Select the correct statement [RPMT 2003] |
| A. | In a full wave rectifier, two diodes work alternately |
| B. | In a full wave rectifier, two diodes work simultaneously |
| C. | The efficiency of full wave and half wave rectifiers is same |
| D. | The full wave rectifier is bi-directional. |
| Answer» B. In a full wave rectifier, two diodes work simultaneously | |
| 19. |
It \[{{\operatorname{H}}_{K}}, {{H}_{C}}\]and \[{{H}_{F}}\]are heat required to raise the temperature of one gram of water by one degree in Celsius, Kelvin and Fahrenheit temperature scales respectively then |
| A. | \[{{\operatorname{H}}_{K}}>{{H}_{C}}>{{H}_{F}}\] |
| B. | \[{{\operatorname{H}}_{F}}>{{H}_{C}}>{{H}_{K}}\] |
| C. | \[{{\operatorname{H}}_{K}}={{H}_{C}}>{{H}_{F}}\] |
| D. | \[{{\operatorname{H}}_{K}}={{H}_{C}}>{{H}_{F}}\] |
| Answer» D. \[{{\operatorname{H}}_{K}}={{H}_{C}}>{{H}_{F}}\] | |
| 20. |
A vector having magnitude 30 unit makes equal angles with each of X, Y and Z axes. The components of vector along each of X, Y and Z axes are |
| A. | \[10\sqrt{3}\] unit |
| B. | \[\frac{10}{\sqrt{3}}\] unit |
| C. | \[15\sqrt{3}\] unit |
| D. | 10 unit |
| Answer» B. \[\frac{10}{\sqrt{3}}\] unit | |
| 21. |
X-rays of \[\lambda =1\,{AA}\] have frequency [DCE 1998] |
| A. | \[3\times {{10}^{8}}\,Hz\] |
| B. | \[3\times {{10}^{18}}\,Hz\] |
| C. | \[3\times {{10}^{10}}\,Hz\] |
| D. | \[3\times {{10}^{15}}\,Hz\] |
| Answer» C. \[3\times {{10}^{10}}\,Hz\] | |
| 22. |
If the length of second's pendulum is decreased by 2%, how many seconds it will lose per day [CPMT 1992] |
| A. | 3927 sec |
| B. | 3727 sec |
| C. | 3427 sec |
| D. | 864 sec |
| Answer» E. | |
| 23. |
A tube shaped like a parallelogram is filled with liquid is kept in a vertical plane. Tube is heated at mid-point of ad. The heat flows only by convection. Then |
| A. | \[{{\operatorname{T}}_{d}}={{T}_{a}}>{{T}_{b}}={{T}_{c}}\] |
| B. | \[{{\operatorname{T}}_{a}}>{{T}_{b}}>{{T}_{c}}>{{T}_{d}}\] |
| C. | \[{{\operatorname{T}}_{a}}>{{T}_{b}}>{{T}_{d}}={{T}_{c}}\] |
| D. | \[{{\operatorname{T}}_{d}}>{{T}_{a}}>{{T}_{b}}>{{T}_{c}}\] |
| Answer» B. \[{{\operatorname{T}}_{a}}>{{T}_{b}}>{{T}_{c}}>{{T}_{d}}\] | |
| 24. |
The volume of a metal ball increases by 0.18% when its temperature is increased by \[{{30}^{o}}C\] What is the coefficient of linear expansion of metal? |
| A. | \[2\times {{10}^{-5}}{{l}^{0}}C\] |
| B. | \[3\times {{10}^{-5}}{{l}^{0}}C\] |
| C. | \[6\times {{10}^{-5}}{{l}^{0}}C\] |
| D. | \[1.8\times {{10}^{-4}}{{l}^{0}}C\] |
| Answer» B. \[3\times {{10}^{-5}}{{l}^{0}}C\] | |
| 25. |
Steam at \[1\,\,\text{atm}\,\,and\,\,100{}^\circ C\] enters a radiator & leaves as water at \[1\,\,\text{atm}\,\,and\,\,80{}^\circ C,\] take \[{{L}_{y}}=540\text{ cal/cm}\] and \[{{s}_{water}}=11\text{ }cal/gm/{}^\circ C.\] If the total energy given off as heat, the % age arises from the cooling of water is |
| A. | 100 |
| B. | 54 |
| C. | 3.6 |
| D. | 8.2 |
| Answer» D. 8.2 | |
| 26. |
A constant volume gas thermometer shows pressure reading of 50 cm and 90 cm of mercury at \[0{}^\circ C\] and \[100{}^\circ C\] respectively. When the pressure reading is 60 cm of mercury, the temperature is |
| A. | \[25{}^\circ C\] |
| B. | \[40{}^\circ C~\] |
| C. | \[15{}^\circ C\] |
| D. | \[{{12.5}^{o}}C\] |
| Answer» B. \[40{}^\circ C~\] | |
| 27. |
Figure shows two coherent sources \[{{S}_{1}}-{{S}_{2}}\] vibrating in same phase. AB is an irregular wire lying at a far distance from the sources \[{{S}_{1}}\] and \[{{S}_{2}}\].Let\[\frac{\lambda }{d}={{10}^{-3}}\].\[\angle BOA={{0.12}^{o}}\] . How many bright spots will be seen on the wire, including points A and B. |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | more than 4 |
| Answer» B. 3 | |
| 28. |
If the sodium light in Young?s double slit experiment is replaced by red light, the fringe width will [MP PMT 2002] |
| A. | Decrease |
| B. | Increase |
| C. | Remain unaffected |
| D. | First increase, then decrease |
| Answer» C. Remain unaffected | |
| 29. |
In Young?s double slit experiment the wavelength of light was changed from 7000 Å to 3500 Å. While doubling the separation between the slits which of the following is not true for this experiment [Orissa JEE 2002] |
| A. | The width of the fringes changes |
| B. | The colour of bright fringes changes |
| C. | The separation between successive bright fringes changes |
| D. | The separation between successive dark fringes remains unchanged |
| Answer» E. | |
| 30. |
Two identical coherent sources are placed on a diameter of a circle of radius R at separation x (<< R) symmetrical about the center of the circle. The sources emit identical wavelength\[\lambda \] each. The number of points on the circle of maximum intersity is\[(x=5\lambda )\] |
| A. | 20 |
| B. | 22 |
| C. | 24 |
| D. | 26 |
| Answer» B. 22 | |
| 31. |
Two waves of intensity I undergo Interference. The maximum intensity obtained is [BHU 2005] |
| A. | I / 2 |
| B. | I |
| C. | 2I |
| D. | 4I |
| Answer» E. | |
| 32. |
The energy of a hydrogen atom in its ground state is \[-13.6\ eV\]. The energy of the level corresponding to the quantum number n = 2 (first excited state) in the hydrogen atom is [CBSE PMT 1996; CBSE PMT 1997, 2001; MP PET 2000; AFMC 2000, 01, 02; BCECE 2003] |
| A. | ? 2.72 eV |
| B. | ? 0.85 eV |
| C. | ? 0.54 eV |
| D. | ? 3.4 eV |
| Answer» E. | |
| 33. |
If the length of a stretched string is shortened by 40% and the tension is increased by 44%, then the ratio of the final and initial fundamental frequencies is [EAMCET 2003] |
| A. | 2 : 1 |
| B. | 3 : 2 |
| C. | 3 : 4 |
| D. | 1 : 3 |
| Answer» B. 3 : 2 | |
| 34. |
(Radius of the earth R = 6400 kilometers) Choose the correct statement from the following : Weightlessness of an astronaut moving in a satellite is a situation of [MP PMT 1995] |
| A. | Zero g |
| B. | No gravity |
| C. | Zero mass |
| D. | Free fall |
| Answer» E. | |
| 35. |
Two rods are joined between fixed supports as shown in the figure. Condition for no change in the lengths of individual rods with the increase of temperature will be (\[{{\alpha }_{1}},{{\alpha }_{2}}\]= linear expansion co-efficient \[{{\text{A}}_{\text{1}}}\text{,}{{\text{A}}_{\text{2}}}\] =Area of rods \[{{\text{Y}}_{\text{1}}}\text{,}{{\text{Y}}_{\text{2}}}\]= Young modulus) |
| A. | \[\frac{{{\text{A}}_{\text{1}}}}{{{\text{A}}_{\text{2}}}}\text{=}\frac{{{\text{ }\!\!\alpha\!\!\text{ }}_{\text{1}}}{{\text{Y}}_{\text{1}}}}{{{\text{ }\!\!\alpha\!\!\text{ }}_{\text{2}}}{{\text{Y}}_{\text{2}}}}\] |
| B. | \[\frac{{{\text{A}}_{\text{1}}}}{{{\text{A}}_{\text{2}}}}\text{=}\frac{{{\text{L}}_{1}}{{\text{ }\!\!\alpha\!\!\text{ }}_{\text{1}}}{{\text{Y}}_{\text{1}}}}{{{\text{L}}_{2}}{{\text{ }\!\!\alpha\!\!\text{ }}_{\text{2}}}{{\text{Y}}_{\text{2}}}}\] |
| C. | \[\frac{{{\text{A}}_{\text{1}}}}{{{\text{A}}_{\text{2}}}}\text{=}\frac{{{\text{L}}_{2}}{{\text{ }\!\!\alpha\!\!\text{ }}_{2}}{{\text{Y}}_{2}}}{{{\text{L}}_{1}}{{\text{ }\!\!\alpha\!\!\text{ }}_{1}}{{\text{Y}}_{1}}}\] |
| D. | \[\frac{{{\text{A}}_{\text{1}}}}{{{\text{A}}_{\text{2}}}}\text{=}\frac{{{\text{ }\!\!\alpha\!\!\text{ }}_{2}}{{\text{Y}}_{2}}}{{{\text{ }\!\!\alpha\!\!\text{ }}_{1}}{{\text{Y}}_{1}}}\] |
| Answer» E. | |
| 36. |
The kinetic energy of an electron revolving around a nucleus will be [BCECE 2004] |
| A. | Four times of P.E. |
| B. | Double of P.E. |
| C. | Equal to P.E. |
| D. | Half of its P.E. |
| Answer» E. | |
| 37. |
A tuning fork of frequency 512 Hz makes 4 beats per second with the vibrating string of a piano. The beat frequency decreases to 2 beats per sec when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was |
| A. | \[510\,Hz\] |
| B. | \[514\,Hz\] |
| C. | \[516\,Hz\] |
| D. | \[508\,Hz\] |
| Answer» E. | |
| 38. |
SI unit of pressure is [EAMCET 1980; DPMT 1984; CBSE PMT 1988; NCERT 1976; AFMC 1991; USSR MEE 1991] |
| A. | Pascal |
| B. | \[Dynes/c{{m}^{2}}\] |
| C. | \[cm\,\] of \[Hg\] |
| D. | Atmosphere |
| Answer» B. \[Dynes/c{{m}^{2}}\] | |
| 39. |
A potential barrier of \[0.3\] Volt exists across a p-n junction. The depletion region is 1 pm wide. The intensity of electric field in this region is E. If electron with speed \[5\times {{10}^{5}}m/s\] approaches this p-n junction from n-side, what will be its speed V on entering the p-side? |
| A. | \[V=12\times {{10}^{5}}m/s\] |
| B. | \[V=1\times {{10}^{4}}m/s\] |
| C. | \[V=3.8\times {{10}^{5}}m/s\] |
| D. | \[V=1.6\times {{10}^{4}}m/s\] |
| Answer» D. \[V=1.6\times {{10}^{4}}m/s\] | |
| 40. |
A mass m attached to a spring oscillates every 2 sec. If the mass is increased by 2 kg, then time-period increases by 1 sec. The initial mass is [CBSE PMT 2000; AIIMS 2000; MP PET 2000; DPMT 2001; Pb. PMT 2003] |
| A. | 1.6 kg |
| B. | 3.9 kg |
| C. | 9.6 kg |
| D. | 12.6 kg |
| Answer» B. 3.9 kg | |
| 41. |
One quality of a thermometer is that its heat capacity should be small. If P is a mercury thermometer, Q is a resistance thermometer and R thermocouple type then [CPMT 1997] |
| A. | P is best, R worst |
| B. | R is best, P worst |
| C. | R is best, Q worst |
| D. | P is best, Q worst |
| Answer» D. P is best, Q worst | |
| 42. |
Two springs with spring constants \[{{K}_{1}}=1500\,N/m\] and \[{{K}_{2}}=3000\,N/m\] are stretched by the same force. The ratio of potential energy stored in spring will be [RPET 2001] |
| A. | 2 : 1 |
| B. | 1 : 2 |
| C. | 4 : 1 |
| D. | 1 : 4 |
| Answer» B. 1 : 2 | |
| 43. |
In case of a forced vibration, the resonance wave becomes very sharp when the |
| A. | quality factor is small |
| B. | damping force is small |
| C. | restoring force is small |
| D. | applied periodic force is small |
| Answer» C. restoring force is small | |
| 44. |
A rod of mass M and length L is hinged at its centre of mass so that it can rotate in a vertical plane. Two springs each of stiffness k are connected at its ends, as shown in the figure. The time period of SHM is |
| A. | \[2\pi \sqrt{\frac{M}{6k}}\] |
| B. | \[2\pi \sqrt{\frac{M}{3k}}\] |
| C. | \[2\pi \sqrt{\frac{ML}{k}}\] |
| D. | \[\pi \sqrt{\frac{M}{6k}}\] |
| Answer» B. \[2\pi \sqrt{\frac{M}{3k}}\] | |
| 45. |
The work done in stretching an elastic wire per unit volume is or strain energy in a stretched string is [NCERT 1981; EAMCET (Med.) 1995; MNR 1981; MP PET 1984; RPMT 1999; DCE 2003] |
| A. | Stress \[\times \] Strain |
| B. | \[\frac{1}{2}\times \]Stress \[\times \]Strain |
| C. | \[2\times \text{strain}\times \text{stress}\] |
| D. | Stress/Strain |
| Answer» C. \[2\times \text{strain}\times \text{stress}\] | |
| 46. |
At what temperature velocity of sound is double than that of at 0°C [RPMT 1999] |
| A. | 819 K |
| B. | 819°C |
| C. | 600°C |
| D. | 600 K |
| Answer» C. 600°C | |
| 47. |
If velocity of sound in a gas is 360 m/s and the distance between a compression and the nearest rarefaction is 1m, then the frequency of sound is [KCET 1999] |
| A. | 90 Hz |
| B. | 180 Hz |
| C. | 360 Hz |
| D. | 720 Hz |
| Answer» C. 360 Hz | |
| 48. |
The radius of the first (lowest) orbit of the hydrogen atom is \[{{a}_{0}}.\] The radius of the second (next higher) orbit will be [MP PET 2002; MP PMT 2004] |
| A. | \[4{{a}_{0}}\] |
| B. | \[6{{a}_{0}}\] |
| C. | \[8{{a}_{0}}\] |
| D. | \[10{{a}_{0}}\] |
| Answer» B. \[6{{a}_{0}}\] | |
| 49. |
Intensity of X-rays depends upon the number of [SCRA 1998; DPMT 2000; AFMC 2001] |
| A. | Electrons |
| B. | Protons |
| C. | Neutrons |
| D. | Positrons |
| Answer» B. Protons | |
| 50. |
X-rays are [CPMT 1975; EAMCET 1995; RPET 2000; SCRA 1994] |
| A. | Stream of electrons |
| B. | Stream of positively charged particles |
| C. | Electromagnetic radiations of high frequency |
| D. | Stream of uncharged particles |
| Answer» D. Stream of uncharged particles | |