MCQOPTIONS
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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.
| 7951. |
An elastic material of Young's modulus Y is subjected to a stress S. The elastic energy stored per unit volume of the material is [MP PET 1991; MP PMT 1990, 96; IIT 1992; AIIMS 1997] |
| A. | \[\frac{2Y}{{{S}^{2}}}\] |
| B. | \[\frac{{{S}^{2}}}{2Y}\] |
| C. | \[\frac{S}{2Y}\] |
| D. | \[\frac{{{S}^{2}}}{Y}\] |
| Answer» C. \[\frac{S}{2Y}\] | |
| 7952. |
In order to make the effective acceleration due to gravity equal to zero at the equator, the angular velocity of rotation of the earth about its axis should be \[(g=10\,m{{s}^{-2}}\] and radius of earth is 6400 kms) [Roorkee 2000] |
| A. | \[0\,\ rad\,{{\sec }^{-1}}\] |
| B. | \[\frac{1}{800}rad\,se{{c}^{-1}}\] |
| C. | \[\frac{1}{80}rad\,se{{c}^{-1}}\] |
| D. | \[\frac{1}{8}rad\,se{{c}^{-1}}\] |
| Answer» C. \[\frac{1}{80}rad\,se{{c}^{-1}}\] | |
| 7953. |
A lorry and a car moving with the same K.E. are brought to rest by applying the same retarding force, then [IIT 1973; MP PMT 2003] |
| A. | Lorry will come to rest in a shorter distance |
| B. | Car will come to rest in a shorter distance |
| C. | Both come to rest in a same distance |
| D. | None of the above |
| Answer» D. None of the above | |
| 7954. |
The speed of light\[(c)\], gravitational constant \[(G)\] and Planck's constant \[(h)\] are taken as the fundamental units in a system. The dimension of time in this new system should be [AMU 1995] |
| A. | \[{{G}^{1/2}}{{h}^{1/2}}{{c}^{-5/2}}\] |
| B. | \[{{G}^{-1/2}}{{h}^{1/2}}{{c}^{1/2}}\] |
| C. | \[{{G}^{1/2}}{{h}^{1/2}}{{c}^{-3/2}}\] |
| D. | \[{{G}^{1/2}}{{h}^{1/2}}{{c}^{1/2}}\] |
| Answer» B. \[{{G}^{-1/2}}{{h}^{1/2}}{{c}^{1/2}}\] | |
| 7955. |
A particle \[P\] is sliding down a frictionless hemispherical bowl. It passes the point \[A\] at \[t=0\]. At this instant of time, the horizontal component of its velocity is \[v\]. A bead \[Q\] of the same mass as \[P\] is ejected from \[A\] at \[t=0\] along the horizontal string \[AB\] (see figure) with the speed \[v\]. Friction between the bead and the string may be neglected. Let \[{{t}_{P}}\] and \[{{t}_{Q}}\] be the respective time taken by \[P\] and \[Q\] to reach the point \[B\]. Then [IIT 1993] |
| A. | \[{{t}_{P}}<{{t}_{Q}}\] |
| B. | \[{{t}_{P}}={{t}_{Q}}\] |
| C. | \[{{t}_{P}}>{{t}_{Q}}\] |
| D. | All of these |
| Answer» B. \[{{t}_{P}}={{t}_{Q}}\] | |
| 7956. |
A P-type semiconductor has acceptor levels 57 meV above the valence band. The maximum wavelength of light required to create a hole is (Planck?s constant h = \[6.6\times {{10}^{-34}}\]J-s) [MP PET 1995] |
| A. | \[57\,{AA}\] |
| B. | \[57\times {{10}^{-3}}\,{AA}\] |
| C. | \[217100\,{AA}\] |
| D. | \[11.61\times {{10}^{-33}}\,{AA}\] |
| Answer» D. \[11.61\times {{10}^{-33}}\,{AA}\] | |
| 7957. |
The number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is of the order of [AMU 1995] |
| A. | \[{{10}^{20}}\] |
| B. | \[{{10}^{19}}\] |
| C. | \[{{10}^{17}}\] |
| D. | \[{{10}^{15}}\] |
| Answer» E. | |
| 7958. |
The maximum velocity of an electron emitted by light of wavelength \[\lambda \] incident on the surface of a metal of work function \[\varphi ,\] is [MP PMT/PET 1998, MP PMT 2003] |
| A. | \[{{\left[ \frac{2(hc+\lambda \varphi )}{m\lambda } \right]}^{1/2}}\] |
| B. | \[\frac{2(hc-\lambda \varphi )}{m}\] |
| C. | \[{{\left[ \frac{2(hc-\lambda \varphi )}{m\lambda } \right]}^{1/2}}\] |
| D. | \[{{\left[ \frac{2(h\lambda -\varphi )}{m} \right]}^{1/2}}\] Where h = Planck's constant, m = mass of electron and c = speed of light. |
| Answer» D. \[{{\left[ \frac{2(h\lambda -\varphi )}{m} \right]}^{1/2}}\] Where h = Planck's constant, m = mass of electron and c = speed of light. | |
| 7959. |
The voltage of an ac source varies with time according to the equation \[V=100\sin \ 100\pi t\cos 100\pi t\] where \[t\] is in seconds and V is in volts. Then [MP PMT 1996; 2000] |
| A. | The peak voltage of the source is 100 volts |
| B. | The peak voltage of the source is 50 volts |
| C. | The peak voltage of the source is \[100/\sqrt{2}\]volts |
| D. | The frequency of the source is 50 Hz |
| Answer» C. The peak voltage of the source is \[100/\sqrt{2}\]volts | |
| 7960. |
Consider the situation shown in the figure. The wire AB is sliding on the fixed rails with a constant velocity. If the wire AB is replaced by semicircular wire, the magnitude of the induced current will [MP PMT 1999] |
| A. | Increase |
| B. | Remain the same |
| C. | Decrease |
| D. | Increase or decrease depending on whether the semicircle bulges towards the resistance or away from it |
| Answer» C. Decrease | |
| 7961. |
In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be [MP PMT 1990; Pb PET 2000] |
| A. | \[3\] |
| B. | \[1/3\] |
| C. | \[\sqrt{3}\] |
| D. | \[1/\sqrt{3}\] |
| Answer» C. \[\sqrt{3}\] | |
| 7962. |
A 500 W heating unit is designed to operate from a 115 volt line. If the line voltage drops to 110 volt, the percentage drop in heat output will be [ISM Dhanbad 1994] |
| A. | 10.20% |
| B. | 8.1% |
| C. | 8.6% |
| D. | 7.6% |
| Answer» D. 7.6% | |
| 7963. |
A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current I passes through the coil, the magnetic field at the centre is [IIT-JEE (Screening) 2001] |
| A. | \[\frac{{{\mu }_{0}}NI}{b}\] |
| B. | \[\frac{2{{\mu }_{0}}NI}{a}\] |
| C. | \[\frac{{{\mu }_{0}}NI}{2(b-a)}\ln \frac{b}{a}\] |
| D. | \[\frac{{{\mu }_{0}}{{I}^{N}}}{2(b-a)}\ln \frac{b}{a}\] |
| Answer» D. \[\frac{{{\mu }_{0}}{{I}^{N}}}{2(b-a)}\ln \frac{b}{a}\] | |
| 7964. |
A gas mixture consists of 2 moles of oxygen and 4 moles argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is [IIT 1999; UPSEAT 2003] |
| A. | 4 RT |
| B. | 15 RT |
| C. | 9 RT |
| D. | 11 RT |
| Answer» E. | |
| 7965. |
Two metal strips that constitute a thermostat must necessarily differ in their [IIT-JEE 1992] |
| A. | Mass |
| B. | Length |
| C. | Resistivity |
| D. | Coefficient of linear expansion |
| Answer» E. | |
| 7966. |
A large open tank has two holes in the wall. One is a square hole of side L at a depth y from the top and the other is a circular hole of radius R at a depth 4y from the top. When the tank is completely filled with water the quantities of water flowing out per second from both the holes are the same. Then R is equal to [IIT-JEE (Screening) 2000] |
| A. | \[2\pi \,L\] |
| B. | \[\frac{L}{\sqrt{2\pi }}\] |
| C. | L |
| D. | \[\frac{L}{2\pi }\] |
| Answer» C. L | |
| 7967. |
A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The e.m.f. of the cell needed to make the bulb glow at full intensity is [MP PMT 1999] |
| A. | 4.5 V |
| B. | 1.5 V |
| C. | 2.67 V |
| D. | 13.5 V |
| Answer» E. | |
| 7968. |
The length of second's hand in watch is 1 cm. The change in velocity of its tip in 15 seconds is [MP PMT 1987] |
| A. | Zero |
| B. | \[\frac{\pi }{30\sqrt{2}}\,\,cm/\sec \] |
| C. | \[\frac{\pi }{30}\,\,cm/\sec \] |
| D. | \[\frac{\pi \sqrt{2}}{30}\,\,cm/\sec \] |
| Answer» E. | |
| 7969. |
Two infinitely long parallel wires having linear charge densities \[{{\lambda }_{1}}\] and \[{{\lambda }_{2}}\] respectively are placed at a distance of R metres. The force per unit length on either wire will be \[\left( K=\frac{1}{4\pi {{\varepsilon }_{0}}} \right)\] [MP PMT/PET 1998; DPMT 2000] |
| A. | \[K\frac{2{{\lambda }_{1}}{{\lambda }_{2}}}{{{R}^{2}}}\] |
| B. | \[K\frac{2{{\lambda }_{1}}{{\lambda }_{2}}}{R}\] |
| C. | \[K\frac{{{\lambda }_{1}}{{\lambda }_{2}}}{{{R}^{2}}}\] |
| D. | \[K\frac{{{\lambda }_{1}}{{\lambda }_{2}}}{R}\] |
| Answer» C. \[K\frac{{{\lambda }_{1}}{{\lambda }_{2}}}{{{R}^{2}}}\] | |
| 7970. |
The apparent depth of water in cylindrical water tank of diameter 2R cm is reducing at the rate of x cm/minute when water is being drained out at a constant rate. The amount of water drained in c.c. per minute is (n1 = refractive index of air, n2 = refractive index of water) [AIIMS 2005] |
| A. | x p R2 n1/n2 |
| B. | x p R2 n2/n1 |
| C. | 2 p R n1/n2 |
| D. | p R2 x |
| Answer» C. 2 p R n1/n2 | |
| 7971. |
The separation between the screen and a concave mirror is 2r. An isotropic point source of light is placed exactly midway between the mirror and the point source. Mirror has a radius of curvature r and reflects 100% of the incident light. Then the ratio of illuminances on the screen with and without the mirror is |
| A. | 10 : 1 |
| B. | 2 : 1 |
| C. | 10 : 9 |
| D. | 9 : 1 |
| Answer» C. 10 : 9 | |
| 7972. |
The separation between the screen and a plane mirror is 2r. An isotropic point source of light is placed exactly midway between the mirror and the screen. Assume that mirror reflects 100% of incident light. Then the ratio of illuminances on the screen with and without the mirror is |
| A. | 10 : 1 |
| B. | 2 : 1 |
| C. | 10 : 9 |
| D. | 9 : 1 |
| Answer» D. 9 : 1 | |
| 7973. |
If the focal length of the objective lens and the eye lens are 4 mm and 25 mm respectively in a compound microscope. The length of the tube is 16 cm. Find its magnifying power for relaxed eye position |
| A. | 32.75 |
| B. | 327.5 |
| C. | 0.3275 |
| D. | None of the above |
| Answer» C. 0.3275 | |
| 7974. |
A compound microscope is used to enlarge an object kept at a distance 0.03m from it?s objective which consists of several convex lenses in contact and has focal length 0.02m. If a lens of focal length 0.1m is removed from the objective, then by what distance the eye-piece of the microscope must be moved to refocus the image |
| A. | 2.5 cm |
| B. | 6 cm |
| C. | 15 cm |
| D. | 9 cm |
| Answer» E. | |
| 7975. |
A particle of mass m is under the influence of a force F which varies with the displacement x according to the relation \[F=-kx+{{F}_{0}}\]in which k and \[{{F}_{0}}\] are constants. The particle when disturbed will oscillate [UPSEAT 2001] |
| A. | about \[x=0,\,\text{with }\omega \ne \sqrt{k/m}\] |
| B. | about \[x=0,\,\text{with }\omega =\sqrt{k/m}\] |
| C. | about \[x={{F}_{0}}/k\,\,\text{with }\omega =\sqrt{k/m}\] |
| D. | about \[x={{F}_{0}}\text{/}k\,\text{with }\omega \ne \sqrt{k/m}\] |
| Answer» D. about \[x={{F}_{0}}\text{/}k\,\text{with }\omega \ne \sqrt{k/m}\] | |
| 7976. |
The radius and mass of earth are increased by 0.5%. Which of the following statements are true at the surface of the earth [Roorkee 2000] |
| A. | g will increase |
| B. | g will decrease |
| C. | Escape velocity will remain unchanged |
| D. | Potential energy will remain unchanged |
| Answer» C. Escape velocity will remain unchanged | |
| 7977. |
If g is the acceleration due to gravity on the earth's surface, the gain in the potential energy of an object of mass m raised from the surface of earth to a height equal to the radius of the earth R, is [IIT 1983] |
| A. | \[\frac{1}{2}mgR\] |
| B. | 2 mgR |
| C. | mgR |
| D. | \[\frac{1}{4}mgR\] |
| Answer» B. 2 mgR | |
| 7978. |
The pair(s) of physical quantities that have the same dimensions, is (are) [IIT 1995] |
| A. | Reynolds number and coefficient of friction |
| B. | Latent heat and gravitational potential |
| C. | Curie and frequency of a light wave |
| D. | Planck's constant and torque |
| Answer» B. Latent heat and gravitational potential | |
| 7979. |
In an interference arrangement similar to Young's double slit experiment, the slits S1 and S2 are illuminated with coherent microwave sources each of frequency 106 Hz. The sources are synchronized to have zero phase difference. The slits are separated by distance d = 150 m. The intensity I\[(\theta )\]is measured as a function ofq, where q is defined as shown. If I0 is maximum intensity, then \[I(\theta )\] for \[0\le \theta \le {{90}^{o}}\]is given by [IIT 1995] |
| A. | \[I(\theta )={{I}_{0}}\]for \[\theta ={{0}^{o}}\] |
| B. | \[I(\theta )={{I}_{0}}/2\]for \[\theta ={{30}^{o}}\] |
| C. | \[I(\theta )={{I}_{0}}/4\]for \[\theta ={{90}^{o}}\] |
| D. | \[I(\theta )\] is constant for all values of q |
| Answer» C. \[I(\theta )={{I}_{0}}/4\]for \[\theta ={{90}^{o}}\] | |
| 7980. |
Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of the rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence [CBSE PMT 1998] |
| A. | \[n>\sqrt{2}\] |
| B. | \[n=1\] |
| C. | \[n=1.1\] |
| D. | \[n=1.3\] |
| Answer» B. \[n=1\] | |
| 7981. |
In the circuit, if the forward voltage drop for the diode is 0.5V, the current will be [UPSEAT 2003] |
| A. | 3.4 mA |
| B. | 2 mA |
| C. | 2.5 mA |
| D. | 3 mA |
| Answer» B. 2 mA | |
| 7982. |
The total power content of an AM wave is 1500 W. For 100% modulation, the power transmitted by the carrier is |
| A. | 500 W |
| B. | 700 W |
| C. | 750 W |
| D. | 1000 W |
| Answer» E. | |
| 7983. |
Hydrogen (H), deuterium , singly ionized helium \[(H{{e}^{+}})\]and doubly ionized lithium \[(Li)\] all have one electron around the nucleus. Consider n =2 to n = 1 transition. The wavelengths of emitted radiations are \[{{\lambda }_{1}},\ {{\lambda }_{2}},\ {{\lambda }_{3}}\]and \[{{\lambda }_{4}}\] respectively. Then approximately [KCET 1994] |
| A. | \[{{\lambda }_{1}}={{\lambda }_{2}}=4{{\lambda }_{3}}=9{{\lambda }_{4}}\] |
| B. | \[4{{\lambda }_{1}}=2{{\lambda }_{2}}=2{{\lambda }_{3}}={{\lambda }_{4}}\] |
| C. | \[{{\lambda }_{1}}=2{{\lambda }_{2}}=2\sqrt{2}{{\lambda }_{3}}=3\sqrt{2}{{\lambda }_{4}}\] |
| D. | \[{{\lambda }_{1}}={{\lambda }_{2}}=2{{\lambda }_{3}}=3\sqrt{2}{{\lambda }_{4}}\] |
| Answer» B. \[4{{\lambda }_{1}}=2{{\lambda }_{2}}=2{{\lambda }_{3}}={{\lambda }_{4}}\] | |
| 7984. |
A photon of \[1.7\times {{10}^{-13}}\]Joules is absorbed by a material under special circumstances. The correct statement is [MP PET 1999; JIPMER 2000] |
| A. | Electrons of the atom of absorbed material will go the higher energy states |
| B. | Electron and positron pair will be created |
| C. | Only positron will be produced |
| D. | Photoelectric effect will occur and electron will be produced |
| Answer» C. Only positron will be produced | |
| 7985. |
An alternating e.m.f. of angular frequency \[\omega \] is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency [Roorkee 1999] |
| A. | \[\frac{\omega }{4}\] |
| B. | \[\frac{\omega }{2}\] |
| C. | \[\omega \] |
| D. | \[2\omega \] |
| Answer» E. | |
| 7986. |
At a place the value of horizontal component of the earth's magnetic field H is \[3\times {{10}^{-5}}\,Weber/{{m}^{2}}\]. A metallic rod AB of length 2 m placed in east-west direction, having the end A towards east, falls vertically downward with a constant velocity of 50 m/s. Which end of the rod becomes positively charged and what is the value of induced potential difference between the two ends [MP PET 1996] |
| A. | End A, \[3\times {{10}^{-3}}\,mV\] |
| B. | End A, 3 mV |
| C. | End B, \[3\times {{10}^{-3}}\,mV\] |
| D. | End B, 3 mV |
| Answer» C. End B, \[3\times {{10}^{-3}}\,mV\] | |
| 7987. |
A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is \[{{2}^{5/4}}\]seconds. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in seconds is [EAMCET (Med.) 2003] |
| A. | \[{{2}^{1/4}}\] |
| B. | \[{{2}^{1/2}}\] |
| C. | 2 |
| D. | \[{{2}^{3/4}}\] |
| Answer» D. \[{{2}^{3/4}}\] | |
| 7988. |
Two coaxial solenoids 1 and 2 of the same length are set so that one is inside the other. The number of turns per unit length are \[{{n}_{1}}\] and \[{{n}_{2}}\]. The currents \[{{i}_{1}}\] and \[{{i}_{2}}\] are flowing in opposite directions. The magnetic field inside the inner coil is zero. This is possible when [Roorkee 2000] |
| A. | \[{{i}_{1}}\ne {{i}_{2}}\] and \[{{n}_{1}}={{n}_{2}}\] |
| B. | \[{{i}_{1}}={{i}_{2}}\]and \[{{n}_{1}}\ne {{n}_{2}}\] |
| C. | \[{{i}_{1}}={{i}_{2}}\] and \[{{n}_{1}}={{n}_{2}}\] |
| D. | \[{{i}_{1}}{{n}_{1}}={{i}_{2}}{{n}_{2}}\] |
| Answer» D. \[{{i}_{1}}{{n}_{1}}={{i}_{2}}{{n}_{2}}\] | |
| 7989. |
The resistance of a heater coil is 110 ohm. A resistance R is connected in parallel with it and the combination is joined in series with a resistance of 11 ohm to a 220 volt main line. The heater operates with a power of 110 watt. The value of R in ohm is [ISM Dhanbad 1994] |
| A. | 12.22 |
| B. | 24.42 |
| C. | Negative |
| D. | That the given values are not correct |
| Answer» B. 24.42 | |
| 7990. |
A closed organ pipe of length L and an open organ pipe contain gases of densities \[{{\rho }_{1}}\] and \[{{\rho }_{2}}\] respectively. The compressibility of gases are equal in both the pipes. Both the pipes are vibrating in their first overtone with same frequency. The length of the open organ pipe is [IIT-JEE (Screening) 2004] |
| A. | \[\frac{L}{3}\] |
| B. | \[\frac{4L}{3}\] |
| C. | \[\frac{4L}{3}\sqrt{\frac{{{\rho }_{1}}}{{{\rho }_{2}}}}\] |
| D. | \[\frac{4L}{3}\sqrt{\frac{{{\rho }_{2}}}{{{\rho }_{1}}}}\] |
| Answer» D. \[\frac{4L}{3}\sqrt{\frac{{{\rho }_{2}}}{{{\rho }_{1}}}}\] | |
| 7991. |
The amplitude of vibration of a particle is given by \[{{a}_{m}}=({{a}_{0}})/(a{{\omega }^{2}}-b\omega +c);\] where \[{{a}_{0}},a,b\] and c are positive. The condition for a single resonant frequency is [CPMT 1982] |
| A. | \[{{b}^{2}}=4ac\] |
| B. | \[{{b}^{2}}>4ac\] |
| C. | \[{{b}^{2}}=5ac\] |
| D. | \[{{b}^{2}}=7ac\] |
| Answer» B. \[{{b}^{2}}>4ac\] | |
| 7992. |
A mono atomic gas is supplied the heat Q very slowly keeping the pressure constant. The work done by the gas will be [BHU 2003; CPMT 2004] |
| A. | \[\frac{2}{3}Q\] |
| B. | \[\frac{3}{5}Q\] |
| C. | \[\frac{2}{5}Q\] |
| D. | \[\frac{1}{5}Q\] |
| Answer» D. \[\frac{1}{5}Q\] | |
| 7993. |
A bimetallic strip is formed out of two identical strips, one of copper and other of brass. The coefficients of linear expansion of the two metals are \[{{\alpha }_{C}}\] and \[{{\alpha }_{B}}\]. On heating, the temperature of the strip goes up by DT and the strip bends to form an arc of radius of curvature R. Then R is [IIT-JEE (Screening) 1999] |
| A. | Proportional to DT |
| B. | Inversely proportional to DT |
| C. | Proportional to \[|{{\alpha }_{B}}-{{\alpha }_{C}}|\] |
| D. | Inversely proportional to \[|{{\alpha }_{B}}-{{\alpha }_{C}}|\] |
| Answer» E. | |
| 7994. |
Water is filled in a cylindrical container to a height of 3m. The ratio of the cross-sectional area of the orifice and the beaker is 0.1. The square of the speed of the liquid coming out from the orifice is (g = 10 m/s2) [IIT JEE 2004] |
| A. | 50 m2/s2 |
| B. | 50.5 m2/s2 |
| C. | 51 m2/s2 |
| D. | 52 m2/s2 |
| Answer» B. 50.5 m2/s2 | |
| 7995. |
When the key K is pressed at time \[t=0\], which of the following statements about the current I in the resistor AB of the given circuit is true [CBSE PMT 1995] |
| A. | I = 2 mA at all t |
| B. | I oscillates between 1 mA and 2mA |
| C. | I = 1 mA at all t |
| D. | At t = 0 , I = 2 mA and with time it goes to 1 mA |
| Answer» E. | |
| 7996. |
Figure shows ABCDEF as a regular hexagon. What is the value of \[\overrightarrow{AB}+\overrightarrow{AC}+\overrightarrow{AD}+\overrightarrow{AE}+\overrightarrow{AF}\] |
| A. | \[\overrightarrow{AO}\] |
| B. | \[2\overrightarrow{AO}\] |
| C. | \[4\overrightarrow{AO}\] |
| D. | \[6\overrightarrow{AO}\] |
| Answer» E. | |
| 7997. |
A point charge q is placed at a distance a/2 directly above the centre of a square of side a. The electric flux through the square is [MP PMT 1997; AMU 1999] |
| A. | \[\frac{q}{{{\varepsilon }_{0}}}\] |
| B. | \[\frac{q}{\pi {{\varepsilon }_{0}}}\] |
| C. | \[\frac{q}{4{{\varepsilon }_{0}}}\] |
| D. | \[\frac{q}{6{{\varepsilon }_{0}}}\] |
| Answer» E. | |
| 7998. |
A 4 mF capacitor, a resistance of 2.5 MW is in series with 12 V battery. Find the time after which the potential difference across the capacitor is 3 times the potential difference across the resistor. [Given ln(2)= 0.693] [IIT-JEE (Screening) 2005] |
| A. | 13.86 s |
| B. | 6.93 s |
| C. | 7 s |
| D. | 14 s |
| Answer» B. 6.93 s | |
| 7999. |
A network of four capacitors of capacity equal to \[{{C}_{1}}=C,\,\,{{C}_{2}}=2C,\,{{C}_{3}}=3C\] and \[{{C}_{4}}=4C\] are conducted in a battery as shown in the figure. The ratio of the charges on \[{{C}_{2}}\] and \[{{C}_{4}}\] is [CBSE PMT 2005] |
| A. | \[\frac{22}{3}\] |
| B. | \[\frac{3}{22}\] |
| C. | \[\frac{7}{4}\] |
| D. | \[\frac{4}{7}\] |
| Answer» C. \[\frac{7}{4}\] | |
| 8000. |
Rest mass energy of an electron is 0.54 MeV. If velocity of the electron is 0.8 c, then K.E. of the electron is |
| A. | 0.36 MeV |
| B. | 0.41 MeV |
| C. | 0.48 MeV |
| D. | 1.32 MeV |
| Answer» B. 0.41 MeV | |