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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.
| 4151. |
4 eV is the energy of the incident photon and the work function in \[2eV.\] What is the stopping potential [DCE 2000; AIIMS 2004] |
| A. | 2V |
| B. | 4V |
| C. | 6V |
| D. | \[2\sqrt{2}V\] |
| Answer» B. 4V | |
| 4152. |
When a metal surface is illuminated by light of wavelengths 400 nm and 250 nm, the maximum velocities of the photoelectrons ejected are \[v\] and \[2v\] respectively. The work function of the metal is (h = Planck?s constant, c = velocity of light in air) [EAMCET (Engg.) 2000] |
| A. | \[2\,hc\,\times {{10}^{6}}\,J\] |
| B. | \[1.5\,hc\,\times {{10}^{6}}\,J\] |
| C. | \[hc\,\times {{10}^{6}}\,J\] |
| D. | \[0.5\,\,hc\,\times {{10}^{6}}\,J\] |
| Answer» B. \[1.5\,hc\,\times {{10}^{6}}\,J\] | |
| 4153. |
Quantam nature of light is explained by which of the following phenomenon [RPET 2000] |
| A. | Huygen wave theory |
| B. | Photoelectric effect |
| C. | Maxwell electromagnetic theory |
| D. | de-Broglie theory |
| Answer» C. Maxwell electromagnetic theory | |
| 4154. |
If work function of metal is 3\[eV\] then threshold wavelength will be [RPMT 2000] |
| A. | 4125 Å |
| B. | 4000 Å |
| C. | 4500 Å |
| D. | 5000 Å |
| Answer» B. 4000 Å | |
| 4155. |
When wavelength of incident photon is decreased then [RPET 2000] |
| A. | Velocity of emitted photo-electron decreases |
| B. | Velocity of emitted photoelectron increases |
| C. | Velocity of photoelectron do not charge |
| D. | Photo electric current increases |
| Answer» C. Velocity of photoelectron do not charge | |
| 4156. |
The stopping potential \[({{V}_{0}})\] [BHU 2000] |
| A. | Depends upon the angle of incident light |
| B. | Depends upon the intensity of incident light |
| C. | Depends upon the surface nature of the substance |
| D. | Is independent of the intensity of the incident light |
| Answer» E. | |
| 4157. |
Light of frequency n is incident on a substance of threshold frequency n0(n0 < n). The energy of the emitted photo-electron will be [MP PET 2000; 03] |
| A. | \[h(\nu -{{\nu }_{0}})\] |
| B. | \[h/\nu \] |
| C. | \[he\,(\nu -{{\nu }_{0}})\] |
| D. | \[h/{{\nu }_{0}}\] |
| Answer» B. \[h/\nu \] | |
| 4158. |
The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies \[f\] and \[2f\] are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B) [EAMCET (Med.) 2000] |
| A. | 1 : 1 |
| B. | 1 : 2 |
| C. | 1 : 3 |
| D. | 1 : 4 |
| Answer» C. 1 : 3 | |
| 4159. |
The energy of a photon is \[E=hv\] and the momentum of photon \[p=\frac{h}{\lambda }\], then the velocity of photon will be [CPMT 1991] |
| A. | E/p |
| B. | Ep |
| C. | \[{{\left( \frac{E}{p} \right)}^{2}}\] |
| D. | \[3\times {{10}^{8}}m/s\] |
| Answer» B. Ep | |
| 4160. |
The momentum of a photon is\[3.3\times {{10}^{-29}}kg-\]m/sec. Its frequency will be [CPMT 1980; MP PET 1992; DPMT 1999] |
| A. | \[3\times {{10}^{3}}Hz\] |
| B. | \[6\times {{10}^{3}}Hz\] |
| C. | \[7.5\times {{10}^{12}}Hz\] |
| D. | \[1.5\times {{10}^{13}}Hz\] |
| Answer» E. | |
| 4161. |
"Lux" is a unit of [Kerala PMT 2001] |
| A. | Luminous intensity of a source |
| B. | Illuminance on a surface |
| C. | Transmission coefficient of a surface |
| D. | Luminous efficiency of source of light |
| Answer» C. Transmission coefficient of a surface | |
| 4162. |
A 60 watt bulb is hung over the center of a table 4 m ´ 4 m at a height of 3 m. The ratio of the intensities of illumination at a point on the centre of the edge and on the corner of the table is [CPMT 1976, 84] |
| A. | \[{{(17/13)}^{3/2}}\] |
| B. | 2 / 1 |
| C. | 17 / 13 |
| D. | 5 / 4 |
| Answer» B. 2 / 1 | |
| 4163. |
A movie projector forms an image 3.5m long of an object 35 mm. Supposing there is negligible absorption of light by aperture then illuminance on slide and screen will be in the ratio of [CPMT 1982] |
| A. | 100 : 1 |
| B. | 104 : 1 |
| C. | 1 : 100 |
| D. | 1 : 104 |
| Answer» C. 1 : 100 | |
| 4164. |
A bulb of 100 watt is hanging at a height of one meter above the centre of a circular table of diameter 4 m. If the intensity at a point on its rim is \[{{I}_{0}}\], then the intensity at the centre of the table will be [CPMT 1996] |
| A. | \[{{I}_{0}}\] |
| B. | \[2\sqrt{5}{{I}_{0}}\] |
| C. | \[2{{I}_{0}}\] |
| D. | \[5\sqrt{5}{{I}_{0}}\] |
| Answer» E. | |
| 4165. |
A lamp is hanging at a height of 4m above a table. The lamp is lowered by 1m. The percentage increase in illuminace will be |
| A. | 40 % |
| B. | 64% |
| C. | 78% |
| D. | 92% |
| Answer» D. 92% | |
| 4166. |
A point source of light moves in a straight line parallel to a plane table. Consider a small portion of the table directly below the line of movement of the source. The illuminance at this portion varies with its distance r from the source as |
| A. | \[E\propto \frac{1}{r}\] |
| B. | \[E\propto \frac{1}{{{r}^{2}}}\] |
| C. | \[E\propto \frac{1}{{{r}^{3}}}\] |
| D. | \[E\propto \frac{1}{{{r}^{4}}}\] |
| Answer» D. \[E\propto \frac{1}{{{r}^{4}}}\] | |
| 4167. |
Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of 60o, by what fraction will the illuminance change |
| A. | It will be doubled |
| B. | It will be halved |
| C. | It will not change |
| D. | It will become one-fourth |
| Answer» D. It will become one-fourth | |
| 4168. |
When sunlight falls normally on earth, a luminous flux of \[1.57\times {{10}^{5}}\ lumen/{{m}^{2}}\] is produced on earth. The distance of earth from sun is \[1.5\times {{10}^{8}}Km\]. The luminous intensity of sun in candela will be |
| A. | \[3.53\times {{10}^{27}}\] |
| B. | \[3.53\times {{10}^{25}}\] |
| C. | \[3.53\times {{10}^{29}}\] |
| D. | \[3.53\times {{10}^{21}}\] |
| Answer» B. \[3.53\times {{10}^{25}}\] | |
| 4169. |
An electric lamp is fixed at the ceiling of a circular tunnel as shown is figure. What is the ratio the intensities of light at base A and a point B on the wall |
| A. | 1 : 2 |
| B. | \[2:\sqrt{3}\] |
| C. | \[\sqrt{3}:1\] |
| D. | \[1:\sqrt{2}\] |
| Answer» E. | |
| 4170. |
Correct exposure for a photographic print is 10 seconds at a distance of one metre from a point source of 20 candela. For an equal fogging of the print placed at a distance of 2 m from a 16 candela source, the necessary time for exposure is |
| A. | 100 sec |
| B. | 25 sec |
| C. | 50 sec |
| D. | 75 sec |
| Answer» D. 75 sec | |
| 4171. |
Which has more luminous efficiency |
| A. | A 40 W bulb |
| B. | A 40 W fluorescent tube |
| C. | Both have same |
| D. | Cannot say |
| Answer» C. Both have same | |
| 4172. |
A lamp is hanging at a height 40 cm from the centre of a table. If its height is increased by 10 cm the illuminance on the table will decrease by |
| A. | 10 % |
| B. | 20% |
| C. | 27% |
| D. | 36% |
| Answer» E. | |
| 4173. |
A point source of 100 candela is held 5m above a sheet of blotting paper which reflects 75% of light incident upon it. The illuminance of blotting paper is |
| A. | 4 phot |
| B. | 4 lux |
| C. | 3 phot |
| D. | 3 lux |
| Answer» C. 3 phot | |
| 4174. |
A lamp is hanging along the axis of a circular table of radius r. At what height should the lamp be placed above the table, so that the illuminance at the edge of the table is \[\frac{1}{8}\] of that at its center [MP PET 2005] |
| A. | \[\frac{r}{2}\] |
| B. | \[\frac{r}{\sqrt{2}}\] |
| C. | \[\frac{r}{3}\] |
| D. | \[\frac{r}{\sqrt{3}}\] |
| Answer» E. | |
| 4175. |
1% of light of a source with luminous intensity 50 candela is incident on a circular surface of radius 10 cm. The average illuminance of surface is |
| A. | 100 lux |
| B. | 200 lux |
| C. | 300 lux |
| D. | 400 lux |
| Answer» C. 300 lux | |
| 4176. |
Inverse square law for illuminance is valid for [CPMT 1978] |
| A. | Isotropic point source |
| B. | Cylindrical source |
| C. | Search light |
| D. | All types of sources |
| Answer» B. Cylindrical source | |
| 4177. |
The intensity of direct sunlight on a surface normal to the rays is \[{{I}_{0}}\]. What is the intensity of direct sunlight on a surface, whose normal makes an angle of 60o with the rays of the sun [CPMT 1981] |
| A. | \[{{I}_{0}}\] |
| B. | \[{{I}_{0}}\left( \frac{\sqrt{3}}{2} \right)\] |
| C. | \[\frac{{{I}_{0}}}{2}\] |
| D. | \[2{{I}_{0}}\] |
| Answer» D. \[2{{I}_{0}}\] | |
| 4178. |
In a movie hall, the distance between the projector and the screen is increased by 1% illumination on the screen is [CPMT 1990] |
| A. | Increased by 1% |
| B. | Decreased by 1% |
| C. | Increased by 2% |
| D. | Decreased by 2% |
| Answer» E. | |
| 4179. |
A lamp is hanging 1 m above the centre of a circular table of diameter 1m. The ratio of illuminaces at the centre and the edge is [NCERT 1982] |
| A. | \[\frac{1}{2}\] |
| B. | \[{{\left( \frac{5}{4} \right)}^{\frac{3}{2}}}\] |
| C. | \[\frac{4}{3}\] |
| D. | \[\frac{4}{5}\] |
| Answer» C. \[\frac{4}{3}\] | |
| 4180. |
The distance between a point source of light and a screen which is 60 cm is increased to 180 cm. The intensity on the screen as compared with the original intensity will be [CPMT 1888] |
| A. | (1 / 9) times |
| B. | (1 / 3) times |
| C. | 3 times |
| D. | 9 times |
| Answer» B. (1 / 3) times | |
| 4181. |
A lamp rated at 100 cd hangs over the middle of a round table with diameter 3 m at a height of 2 m. It is replaced by a lamp of 25 cd and the distance to the table is changed so that the illumination at the centre of the table remains as before. The illumination at edge of the table becomes X times the original. Then X is [CPMT 1989] |
| A. | \[\frac{1}{3}\] |
| B. | \[\frac{16}{27}\] |
| C. | \[\frac{1}{4}\] |
| D. | \[\frac{1}{9}\] |
| Answer» B. \[\frac{16}{27}\] | |
| 4182. |
Lux is equal to [CPMT 1993] |
| A. | 1 lumen/m2 |
| B. | 1 lumen/cm2 |
| C. | 1 candela/m2 |
| D. | 1 candela/cm2 |
| Answer» D. 1 candela/cm2 | |
| 4183. |
A small lamp is hung at a height of 8 feet above the centre of a round table of diameter 16 feet. The ratio of intensities of illumination at the centre and at points on the circumference of the table will be [CPMT 1984, 1996] |
| A. | 1 : 1 |
| B. | 2 : 1 |
| C. | \[2\sqrt{2}:1\] |
| D. | 3 : 2 |
| Answer» D. 3 : 2 | |
| 4184. |
The maximum illumination on a screen at a distance of 2 m from a lamp is 25 lux. The value of total luminous flux emitted by the lamp is [JIMPER 1997] |
| A. | 1256 lumen |
| B. | 1600 lumen |
| C. | 100 candela |
| D. | 400 lumen |
| Answer» B. 1600 lumen | |
| 4185. |
If the luminous intensity of a 100 W unidirectional bulb is 100 candela, then total luminous flux emitted from the bulb is [AIIMS 1998] |
| A. | 861 lumen |
| B. | 986 lumen |
| C. | 1256 lumen |
| D. | 1561 lumen |
| Answer» D. 1561 lumen | |
| 4186. |
An electric bulb illuminates a plane surface. The intensity of illumination on the surface at a point 2m away from the bulb is \[5\times {{10}^{-4}}\] phot (lumen/cm2). The line joining the bulb to the point makes an angle of 60o with the normal to the surface. The intensity of the bulb in candela is [IIT-JEE 1980; CPMT 1991] |
| A. | \[40\sqrt{3}\] |
| B. | 40 |
| C. | 20 |
| D. | \[40\times {{10}^{-4}}\] |
| Answer» C. 20 | |
| 4187. |
Total flux produced by a source of 1 cd is [CPMT 2001] |
| A. | \[\frac{1}{4\pi }\] |
| B. | \[8\pi \] |
| C. | \[4\pi \] |
| D. | \[\frac{1}{8\pi }\] |
| Answer» D. \[\frac{1}{8\pi }\] | |
| 4188. |
If luminous efficiency of a lamp is 2 lumen/watt and its luminous intensity is 42 candela, then power of the lamp is [AFMC 1998] |
| A. | 62 W |
| B. | 76 W |
| C. | 138 W |
| D. | 264 W |
| Answer» E. | |
| 4189. |
A body of mass 2 kg moving with a velocity of 3 m/sec collides head on with a body of mass 1 kg moving in opposite direction with a velocity of 4 m/sec. After collision, two bodies stick together and move with a common velocity which in m/sec is equal to [NCERT 1984; MNR 1995, 98; UPSEAT 2000] |
| A. | 1/4 |
| B. | 1/3 |
| C. | 2/3 |
| D. | ¾ |
| Answer» D. ¾ | |
| 4190. |
A bullet hits and gets embedded in a solid block resting on a horizontal frictionless table. What is conserved? [NCERT 1973; CPMT 1970; AFMC 1996; BHU 2001] |
| A. | Momentum and kinetic energy |
| B. | Kinetic energy alone |
| C. | Momentum alone |
| D. | Neither momentum nor kinetic energy |
| Answer» D. Neither momentum nor kinetic energy | |
| 4191. |
A completely inelastic collision is one in which the two colliding particles |
| A. | Are separated after collision |
| B. | Remain together after collision |
| C. | Split into small fragments flying in all directions |
| D. | None of the above |
| Answer» C. Split into small fragments flying in all directions | |
| 4192. |
A mass of 10 gm moving with a velocity of 100 cm/s strikes a pendulum bob of mass 10 gm. The two masses stick together. The maximum height reached by the system now is \[(g=10\,m/{{s}^{2}})\] [MP PET 1993] |
| A. | Zero |
| B. | 5 cm |
| C. | 2.5 cm |
| D. | 1.25 cm |
| Answer» E. | |
| 4193. |
A bullet of mass a and velocity b is fired into a large block of mass c. The final velocity of the system is [AFMC 1981, 94, 2000; NCERT 1971; MNR 1998] |
| A. | \[\frac{c}{a+b}\cdot b\] |
| B. | \[\frac{a}{a+c}\cdot b\] |
| C. | \[\frac{a+b}{c}.a\] |
| D. | \[\frac{a+c}{a}\cdot b\] |
| Answer» C. \[\frac{a+b}{c}.a\] | |
| 4194. |
Which of the following is not an example of perfectly inelastic collision [AFMC 2005] |
| A. | A bullet fired into a block if bullet gets embedded into block |
| B. | Capture of electrons by an atom |
| C. | A man jumping on to a moving boat |
| D. | A ball bearing striking another ball bearing |
| Answer» E. | |
| 4195. |
When two bodies stick together after collision, the collision is said to be |
| A. | Partially elastic |
| B. | Total elastic |
| C. | Total inelastic |
| D. | None of the above |
| Answer» D. None of the above | |
| 4196. |
A body of mass 4 kg moving with velocity 12 m/s collides with another body of mass 6 kg at rest. If two bodies stick together after collision, then the loss of kinetic energy of system is [J&K CET 2005] |
| A. | Zero |
| B. | 288 J |
| C. | 172.8 J |
| D. | 144 J |
| Answer» D. 144 J | |
| 4197. |
Two bodies of masses 0.1 kg and 0.4 kg move towards each other with the velocities 1 m/s and 0.1 m/s respectively, After collision they stick together. In 10 sec the combined mass travels [Pb. PET 2003] |
| A. | 120 m |
| B. | 0.12 m |
| C. | 12 m |
| D. | 1.2 m |
| Answer» E. | |
| 4198. |
In an inelastic collision, what is conserved [DCE 2004] |
| A. | Kinetic energy |
| B. | Momentum |
| C. | Both (a) and (b) |
| D. | Neither (a) nor (b) |
| Answer» C. Both (a) and (b) | |
| 4199. |
A bullet of mass m moving with velocity v strikes a block of mass M at rest and gets embedded into it. The kinetic energy of the composite block will be [MP PET 2002] |
| A. | \[\frac{1}{2}m{{v}^{2}}\times \frac{m}{(m+M)}\] |
| B. | \[\frac{1}{2}m{{v}^{2}}\times \frac{M}{(m+M)}\] |
| C. | \[\frac{1}{2}m{{v}^{2}}\times \frac{(M+m)}{M}\] |
| D. | \[\frac{1}{2}M{{v}^{2}}\times \frac{m}{(m+M)}\] |
| Answer» B. \[\frac{1}{2}m{{v}^{2}}\times \frac{M}{(m+M)}\] | |
| 4200. |
A body of mass 40kg having velocity 4 m/s collides with another body of mass 60kg having velocity 2 m/s. If the collision is inelastic, then loss in kinetic energy will be [Pb. PMT 2001] |
| A. | 440 J |
| B. | 392 J |
| C. | 48 J |
| D. | 144 J |
| Answer» D. 144 J | |