Consortium of Medical, Engineering and Dental Colleges of Karnataka (COMEDK) under graduate entrance exam 60 multiple choice questions on Physics with answers.
Ques: In a mean life of a radioactive sample
(a) About 1/3 of substance disintegrates
(b) About 2/3 of the substance disintegrates
(c) About 90% of the substance disintegrates
(d) Almost all the substance disintegrates
Ques. A 2 cm high object is placed on the principal axis of a concave mirror at a distance of 12 cm from the pole. If the image is inverted, real and 5 cm high, find the focal length of mirror
(a) 7.6 cm
(b) 9.6 cm
(c) 8.6 cm
(d) 12.6 cm
Ques. The horizontal component of earth’s magnetic field at any places is 0.36 x 10–4 Weber/m2. If the angle of dip at that place is 60° then the value of vertical component of earth’s magnetic field will be (in Wb/m2)
(a) 0.12 x 10–4
(b) 0.24 x 10–4
(c) 0.40 x 10–4
(d) 0.62 x 10–4
Ques. The fringe width for red colour as compared to that for violet colour is approximately
(a) Three times
(b) Double
(c) Four times
(d) Eight times
Ques. A sound-source is having a simple harmonic motion of amplitude 17 cm. A detector is placed along the line of motion of the source. The frequency of the sound emitted from the source is 800 Hz and the velocity of sound is 340 m/s. If the band width of frequency observed by the detector is 8 Hz, then the period of the motion of source is
(a) 1 sec
(b) 0.85 sec
(c) 0.63 sec
(d) 0.45 sec
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Ques. In an experiment with sonometer a tuning fork of frequency 256 Hz resonates with a length of 25 cm and another tuning fork resonates with a length of 16 cm. Tension of the string remaining constant the frequency of the second tuning fork is :
(a) 163.84 Hz
(b) 400 Hz
(c) 320 Hz
(d) 204.8 Hz
Ques. A 10 kg mass falls through 25 m on to the ground and bounces to a height of 0.50 m. Assume that all potential energy lost is used in heating up the mass. The temperature rise will be (given specific heat of the material is 252 Joule / kg K)
(a) 0.95 K
(b) 0.095 K
(c) 0.0095 K
(d) None of these values
Ques. In an experiment of triode it is found that at a constant plate potential of 200V the value plate current becomes from 6.5 mA to 11.5 mA and the grid potential becomes from –2V and –1V The mutual conductance of triode will be
(a) 5 mho
(b) 0.5 mho
(c) 15 mho
(d) 5 x 10–3 mho
Ques. On placing a light source at a distance of 20 cm from a photoelectric cell, the stopping potential is found to be 0.6 V. If the distance of source is now changed to 40 cm, then the stopping potential will become
(a) 2.4 V
(b) 1.8 V
(c) 0.6 V
(d) 0.3 V
Ques. Monochromatic light incident on a metal surface emits electron with kinetic energy from zero to 2.6 eV. What is the least incident energy if the tightly bound electron needs 4.2 eV to remove
(a) 1.6 eV
(b) From 1.6 eV to 6.8 eV
(c) 6.8 eV
(d) > 6.8 eV
Ques. The phenomenon of production of magnetic field on passing an electric current in a straight conducting wire is based on the law of
(a) Faraday
(b) Coulomb
(c) Ampere
(d) Oersted
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Ques. A siphon in use is demonstrated in the following figure. The density of the liquid following in siphon is 1.5 gm/cc. The pressure difference between the point P and S will be
(a) 105 N / m
(b) 2 x 105 N / m
(c) Zero
(d) Infinity
Ques. Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand
(a) None
(b) 1
(c) 2
(d) 3
Ques. An aeroplane flying in the sky dives with a speed of 100m/s in a vertical circle of radius 200m. Weight of the pilot sitting in it is 75 Kg. The force with which the pilot presses his seat when aeroplane is at the highest position is
(a) 200 Kg. wt.
(b) 400 Kg. wt.
(c) 100 Kg. wt.
(d) 300 Kg. wt.
Ques. A person suffering from ‘presbyopia’ (myopia and hyper metropia both defects) should use
(a) A concave lens
(b) A convex lens
(c) A bifocal lens whose lower portion is convex
(d) A bifocal lens whose upper portion is convex
Ques. A body of mass 1 kg is projected with a velocity of 10m/s at an angle 600 w.r.t. horizontal ground. The maximum value of gravitational potential energy in its motion is
(a) 50 J
(b) 25 J
(c) 35 J
(d) 37.5 J
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Ques. X-rays are not used for radar purpose because
(a) They are not reflected by the target
(b) They are not electromagnetic waves
(c) They are completely absorbed by the air
(d) They sometimes damage the target
Ques. A light bulb is placed between two plane mirrors inclined at an angle of 60o. The number of images formed are
(a) 6
(b) 2
(c) 5
(d) 4
Ques. A watch shows time as 3 : 25 when seen through a mirror, time appeared will be
(a) 8 : 35
(b) 9 : 35
(c) 7 : 35
(d) 8 : 25
Ques. An electric tea kettle has two heating coils. When one of the coils is switched on, the kettle begins to boil in six minutes. When the other coil is switched on, the boiling begins in 8 minutes. When both the coils are switched on in series, then boiling will begin in
(a) 10 min
(b) 14 min
(c) 18 min
(d) 20 min
Ques. If two bulbs marked 100W, 250 V and 50 W, 250 V are connected in series with a 250 V source, then
(a) Both bulbs will get fused
(b) 100 W bulb will get fused
(c) 50 W bulb will get fused
(d) None of two will get fused
Ques. The extension in a string obeying Hooke’s low v is x. The speed of sound in the stretched string is v. If the extension in the string is increased to 1.5x, the speed of sound will be
(a) 1.22 v
(b) 0.61 v
(c) 1.50 v
(d) 0.75 v
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Ques. The frequency of whistle of an engine appears decreasing in the ratio 8/9 as the engine passes a stationary observer. If the velocity of the sound is 340 m/s, then the speed of the engine will be
(a) 10 m/s
(b) 20 m/s
(c) 25 m/s
(d) 30 m/s
Ques. Heat of neutralization of strong acid against strong base is constant and is equal to
(a) 13.7 kcal
(b) 57 kJ
(c) 5.7 x 104 J
(d) All of the above
Ques. A piece of copper and the other of germanium are cooled from the room temperature to 80K, then
(a) Resistance of each will increases
(b) Resistance of each will decreases
(c) The resistance of copper will increases while that of germanium decreases
(d) The resistance of copper will decreases while that of germanium increases
Ques. The thermal conductivity of a material in CGS system is 0.4. In steady state, the rate of flow of heat 10 cal/sec-cm2, then the thermal gradient will be
(a) 10o C/ cm
(b) 12o C/ cm
(c) 25o C/ cm
(d) 20o C/ cm
Ques. An e.m.f. of 5volt is produced by a self inductance, when the current changes at a steady rate from 3 to 2 ampere in 1 millisecond. The value of self inductance is
(a) Zero
(b) 5 henry
(c) 5000 henry
(d) 5 millihenry
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Ques. The electrons are emitted in a photoelectric effect from a metal surface
(a) Only if the frequency of radiation is above a certain threshold value
(b) Only if the temperature of the surface is high
(c) At a rate that is independent of the nature of metal
(d) With a maximum velocity proportional to the frequency of incident radiation
Ques. A wire bent in the form of a right angled triangle ABC as shown in fig. carries a current 1A. it is placed in the region of a uniform magnetic induction field B = 0.2 T as shown in fig. If AC = 1m the net force on the wire is
(a) 1.73 N
(b) 3.46 N
(c) 2.732 N
(d) 0
Ques. There is small hole of diameter 2 mm in the wall of a water tank at a depth of 10 m below free water surface. The velocity of efflux of water from the hole will be
(a) 0.14 m/s
(b) 1.4 m/s
(c) 0.014 m/s
(d) 14 m/s
Ques. A block of mass 100 kg is lying on the surface of a trolley. The coefficient of friction between the surface and the block is 0.7. If the truck accelerates at 6 m s–2, the force of friction will be
(a) 420 N
(b) 600 N
(c) 700 N
(d) none of these
Ques. When an air column at 15°C and a tuning fork are sounded together then 4 beats/sec are produced. The frequency of the fork is less then that of the air column. When the temperature falls to 10°C then the beat frequency decreases by one. The frequency of the fork will be
(a) 110 Hz
(b) 114 Hz
(c) 113 Hz
(d) 106 Hz
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Ques. An artificial satellite is revolving round the earth in a circular orbit. Its velocity is half the escape velocity. Its height from earth’s surface is
(a) 6400 Km
(b) 12800 Km
(c) 3200 Km
(d) 1600 Km
Ques. An object is placed 12 cm to the left of a converging lens of focal length 8 cm. Another converging lens of 6 cm focal length is placed at a distance of 30 cm to the right of the first lens. The second lens will produce
(a) No image
(b) A virtual enlarged image
(c) A real enlarged image
(d) A real smaller image
Ques. In case of a semiconductor, which of the following statement is wrong
(a) Doping increases conductivity
(b) Temperature coefficient of resistance is negative
(c) Resisitivity is in between that of a conductor and insulator
(d) At absolute zero temperature, it behaves like a conductor
Ques. Which of the following is incorrect statement regarding photon
(a) Photon exerts no pressure
(b) Photon energy is hv
(c) Photon rest mass is zero
(d) None of these
Ques. The dimensionless physical quantity is
(a) universal gravitational constant
(b) planck constant
(c) relative velocity
(d) relative density
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Ques. It is desired to photograph the image of an object placed at a distance of 3m from the plane mirror. The camera which is at a distance of 4.5m from the mirror should be focussed for a distance of
(a) 3m
(b) 4.5m
(c) 6m
(d) 7.5m
Ques. An object is placed at a distance of 5 cm from a convex lens of focal length 10 cm, then the image is
(a) real, diminished and at a distance of 10 cm from the lens
(b) real, enlarged and at a distance of 10 cm from the lens
(c) virtual, enlarged and at a distance of 10 cm from the lens
(d) virtual, diminished and at a distance of 10 cm from the lens
Ques. The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statement is true ?
(a) Its kinetic energy increases and its potential and total energy decreases
(b) Its kinetic energy decreases, potential energy increases and its total energy remains the same
(c) Its kinetic and total energy decreases and its potential energy increases
(d) Its kinetic, potential and total energy decreases
Ques. A coil, in which number of turns and the mean area 103 and 500 cm2 respectively, is lying at right angles to a magnetic field of 0.4 Gauss. If the coil is turned through 180° in 1/10 second then the average induced e.m.f. will be
(a) 0.04 V
(b) 4 V
(c) 0.4 V
(d) 40 V
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Ques. The energy required to excite an electron from n=2 to n=3 energy state is 47.2eV. The charge number of the nucleus, around which the electron is revolving, will be
(a) 5
(b) 10
(c) 15
(d) 20
Ques. A logic gate is an electronic circuit which
(a) Makes logic decisions
(b) Allows electrons to flow only in one direction
(c) Works on binary algebra
(d) Alternates between 0 and 1
Ques. A wire length 1m moves in a direction perpendicular to its length with a velocity of 100m/s in a magnetic field of 1 tesla. The magnetic field is perpendicular to the length of the wire. If the direction of motion makes an angle of 30° with the magnetic field, then emf induced in the wire will be
(a) 10 V
(b) 20 V
(c) 50 V
(d) 100 V
Ques. A fully charged capacitor is discharged through a inductor of 0.5mH. Current increases from 0 to 1.5A in 2.5 
s. The developed across the inductor is
(a) 76 V
(b) 125 V
(c) 300 V
(d) 1875 V
Ques. A train sound its whistle as it approaches and leaves an observer standing at a railroad crossing. If the frequency heard by the observer are 219 Hz and 184 Hz, respectively, and if the speed of sound is 340 m/s, then the speed of the train and frequency of its whistle, respectively, are
(a) 29.5 m/s, 200 Hz
(b) 30.5 m/s, 210 Hz
(c) 31.5 m/s, 220 Hz
(d) 32.5 m/s, 230 Hz
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Ques. The Potential difference of a solid and hollow sphere of same radii is equal, then under this condition
(a) The charge on solid sphere will be more
(b) The charge on hollow sphere will be more
(c) There will be equal charge on both
(d) The ratio of the charges on the two spheres is not constant
Ques. A water drop of radius 0.3 mm is falling through air with a velocity of 1 m/s. If the coefficient of viscosity of air 18 x 10–5 Kg/m – s, then the viscous force acting on the drop will be
(a) 1017 x 10–9 Newton
(b) 1017 x 10–4 Newton
(c) 1017 x 10–10 Newton
(d) 1017 x 10–5 Newton
Ques. An endoscope is employed by a physician to view the internal parts of a body organ. It is based on the principle of
(a) Refraction
(b) Reflection
(c) Total internal reflection
(d) Dispersion
Ques. A pulley is attached to the ceiling of a lift moving upwards. Two particles are attached to the two ends of a string passing over the pulley. The masses of the particles are in the ratio 2:1. If the acceleration of the particles is g/2, then the acceleration of the lift will be
(a) g
(b) g/2
(c) g/3
(d) g/4
Ques. A logic gate is an electronic circuit which
(a) Makes logic decisions
(b) Allows electrons flow only in one direction
(c) Works binary algebra
(d) Alternates between 0 and 1 values
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Ques. If the energy of the photon is increased by a factor of 4, then its momentum
(a) Does not change
(b) Decreases by a factor of 4
(c) Increases by a factor of 4
(d) Decreases by a factor of 2
Ques. A particle moving in one dimension with a constant acceleration of 2 m/s2 is observed to cover a distance of 5 m during a particular interval of one second. The distance covered by particle in the next one second interval is (in metres)
(a) 12
(b) 6
(c) 7
(d) 10
Ques. A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the
(a) First
(b) Second
(c) Fourth
(d) Last
Ques. A thin walled glass sphere of radius 2.5 cm is filled with water. An object is placed at 7.5 cm from the surface of the sphere. Neglecting the effect of glass wall, at what distance the image of the object, measured from the centre of sphere is formed
(a) 20 cm
(b) 15 cm
(c) 10 cm
(d) 7.5 cm
Ques. A 280 ohm electric bulb is connected to 200 V electric line. The peak value of current in the bulb will be
(a) About one ampere
(b) Zero
(c) About one ampere
(d) About four ampere
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Ques. A mass m is moving with a constant velocity along a line parallel to x–axis. Its angular momentum with respect to origin on z–axis is
(a) zero
(b) remain constant
(c) goes on increasing
(d) goes on decreasing
Ques. The surface area of a black body is 5 x 10–4 m2 and its temperature is 727°C. The amount of radiation emitted by it per minute will be
(a) 170 Joule
(b) 17 Joule
(c) 1701 Joule
(d) 0.17 Joule
Ques. The electromagnetic waves that has highest wavelength is
(a) X-rays
(b) Ultraviolet rays
(c) Infra-red rays
(d) Microwaves
Ques. Dopping materials are called impurities, because they
(a) Decrease the number of charge carriers
(b) Charge the chemical properties of semiconductors
(c) Make semiconductors less then 100 percent pure
(d) Alter the crystal structure of pure semiconductors
Ques. The self-inductance of a coil area 1cm2 and of turns 100 is 1mH. When 2A current is passed in the coil, the magnetic induction at the center of the coil will be
(a) 0.2 Wb/m2
(b) 0.4 Wb/m2
(c) 0.8 Wb/m2
(d) 1 Wb/m2
