40 multiple choice Physics questions for Vellore Institute of Technology Engineering Entrance Exam.

**Ques:** Carbon dating is best suited for determining the age of fossils if their age in years is of the order of

(a) 10^{3}

(b) 10^{4
}(c) 10^{5}

(d) 10^{6}

**Ques. **If the density of a gas at NTP is 1.3 mg/cm^{3} and velocity of sound in it is 330 m/s. The number of degree of freedom of gas molecule is

(a) 2

(b) 3

(c) 4

(d) 5

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**Ques.** A ray of light incidents on a plane mirror at an angle of 30^{o}. The deviation produced in the ray is

(a) 30^{o}

(b) 60^{ o}

(c) 90^{ o}

(d) 120^{ o
}

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**Ques. **An *X*-ray tube operating at 50 *kV* converts 1% energy in the form of *X*-ray. If the amount of heat produced is 495 watt, then the number of electrons colliding with the target per second is

(a) 6.25 x 10^{16}

(b) 4.15 x 10^{16}

(c) 3.2 x 10^{16}

(d) 1.2 x 10^{18}

**Ques.** A stream of electron of velocity 3 x 10^{7} m/s is deflected 2mm in passing 10 cm through an electric field of 1800V/m perpendicular to their path. The value of e/m for electrons will be

(a) 1.78 x 10^{11}coul/kg

(b) 2 x 10^{11} coul/kg

(c) 2.22 x 10^{11}coul/kg

(d) 3.61 x 10^{11} coul/kg

**Ques. **The aperture of a telescope is made large, because

(a) To increase the intensity of image

(b) To decrease the intensity of image

(c) To have greater magnification

(d) To have lesser resolution

**Ques. **A man standing in a swimming pool looks at a stone lying at the bottom. The depth of the swimming pool is *h*. At what distance from the surface of water is the image of the stone formed (Line of vision is normal; Refractive index of water is *n*)

(a) *h* / *n
*(b)

*n*/

*h*

(c)

*h*

(d)

*hn*

**Ques. **The average life time of an excited state of hydrogen atom is 10^{–8}. An electron is revolving in the second orbit with a velocity of 1.1 x 101^{6} m/s. What is the frequency of electron in this orbit

(a) 2.4 x 10^{14} Hz

(b) 6.18 x 10^{14} H*z
*(c) 8.2 x 10

^{14}H

*z*

(d) None of these

**Ques. **In an *X-*rays tube, the intensity of the emitted *X-*rays beam is increased by

(a) Increasing the filament current

(b) Decreasing the filament current

(c) Increasing the target potential

(d) Decreasing the target potential

**Ques.** A ray of light is incidenting normally on a plane mirror. The angle of reflection will be

(a) 0^{ o}

(b) 90^{ o}

(c) Will not be reflected

(d) None of the above

**Ques. **If R_{1 }and R_{2} are respectively the filament resistance of a 200 watt bulb and a 100 watt bulb designed to operate on the same voltage

(a) R_{1} is two times R_{2}

(b) R_{2} is two times R_{1
}(c) R_{2} is four times R_{1}

(d) R_{1} is four times R_{2}

**Ques.** When a plane mirror is placed horizontally on a level ground at a distance of 60 m from the foot of a tower, the top of the tower and its image in the mirror subtend an angle of 90^{o} at the eye. The height of the tower will be

(a) 30m

(b) 60m

(c) 90m

(d) 120m

**Ques. **Electromagnetic radiations described by the equation E = 100 [sin (2 x 10^{15}) t + sin (6.28 x 10^{15})t] V/m are incident on a photosensitive surface having work function 2 *eV*. The maximum kinetic energy of photo-electrons will be

(a) 0.125 *eV*

(b) 2.125 *eV
*(c) 4.125

*eV*

(d) 6.125

*eV*

**Ques.** The half life of radioactive Radon is 3.8 days. The time at the end of which (1/20)th of the Radon sample will remain undecayed is, [given log_{10}e = 0.4343]

(a) 13.8 days

(b) 16.5 days

(c) 53 days

(d) 76 days

**Ques. **A long solenoid contains 1000 turns/cm and an alternating current of peak value 1*A* is following in it. A search coil of area of cross-section 1 x 10^{–4} m^{2} and having 50 turns is placed inside the solenoid with its plane perpendicular to the axis of the solenoid. A peak voltage of 2p^{2} x 10^{–2} V is produced in the search coil. The frequency of current in the solenoid will be

(a) 50 *Hz*

(b) 100 *Hz
*(c) 500

*Hz*

(d) 1000

*Hz*

**Ques. **Which of the following statement is wrong**?
**(a) Infrared photon has more energy than the photon of visible light

(b) Photographic plates are sensitive to ultraviolet rays

(c) Photographic plates can be made sensitive to infrared rays

(d) Infrared rays are invisible but can cast shadows like visible light rays

**Ques. **A block of mass 2 Kg. is lying on an inclined plane, inclined to the horizontal at an angle of 30°. The magnitude of frictional force acting on the block if the coefficient of friction between the block and the plane is 0.7, will be

(a) 11.9 Newton

(b) 1.19 Newton

(c) 0.119 Newton

(d) 1119 Newton

**Ques.** If RMS velocity of molecules of a diatomic gas is increased to 1.5 times. If the process is done adiabatically. Then the ratio of initial volume to final volume will be

(a) (1.5)^{5}

(b) (1.5)^{4
}(c) (1.5)^{3}

(d) (1.5)^{2.5
}

**Ques. **The temperature coefficient of resistance of a wire is 0.00125^{o} C^{–1} At 300 *K* its resistance is one ohm. The resistance of the wire will be 2 ohm at

(a) 1154 *K*

(b) 1100 *K
*(c) 1400

*K*

(d) 1127

*K*

**Ques. **10 ampere alternating current flows through the primary coil of transformer at 230 volt. If a voltage of 23000 volt is produced in the secondary coil and half of the power is lost in it, then the current in the secondary coil will be

(a) 0.05 *A*

(b) 0.5 *A
*(c) 0.1

*A*

(d) 1

*A*

**Ques. **A layer of glycerine of thickness 1 mm is enclosed between a big plate and another plane of area 10^{–2} m^{2} If the coefficient of viscosity of glycerine is 1 kg /m – s, then the force in Newton required to move the plate with a velocity of 0.07 m/s will be

(a) 7

(b) 0.7

(c) 70

(d) 0.07

**Ques. **A copper solid cube of 60 mm side is subjected to a pressure of 2.5 x 10^{7} Pa. If the bulk modulus of copper is 1.25 x 10^{11} N/m^{2}, the change in the volume of cube is

(a) –43.2 m^{3}

(b) –43.2 mm^{3
}(c) –43.2 cm^{3}

(d) –432 mm^{3}

**Ques. **According to de-Broglie, the de-Broglie wavelength for electron in an orbit of hydrogen atom is 10^{–9} *m*. The principle quantum number for this electron is

(a) 1

(b) 2

(c) 3

(d) 4

**Ques. **A telescope with objective of focal length 60 cm and eye-piece of focal length 5 cm is focused on a far distance object such that parallel rays emerge from the eye-piece. If the object subtends an angle 2° on the objective, then angular width of image will be

(a) 10°

(b) 24°

(c) 50°

(d) 62°

**Ques.** A plane mirror makes an angle of 30^{o} with horizontal. If a vertical ray strikes the mirror, find the angle between mirror and reflected ray

(a) 30^{ o}

(b) 45^{ o}

(c) 60^{ o}

(d) 90^{ o
}

**Related:** Nuclear Chemistry Online Test

**Ques. **In Young’s double slit experiment, when a thin transparent sheet of thickness 2.5 x 10^{–3 }cm is placed on one of the slits, then the interference pattern is displaced by a distance equal to 20 times of the fringe width. If the wave length of light used is 5000Å, then the refractive index of sheet is

(a) 2.3

(b) 1.95

(c) 1.6

(d) 1.4

**Ques. **A capillary tube of radius *r* can support a liquid of weight 6.28 x 10^{–4} N. If the surface tension of the liquid is 5 x 10^{–2} N/m, the radius of the capillary tube must be

(a) 2.0 x 10^{–3} m

(b) 2.0 x 10^{–4} m

(c) 1.5 x 10^{–3} m

(d) 2.5 x 10^{–4} m

**Ques. **A small magnet is along the axis of a coil and its distance from the coil is 80cm. In this position the flux linked with the coil are 4 x 10^{–5} weber turns. If the coil is displaced 40cm towards the magnet in 0.08 second, then the induced e.m.f. produced in the coil will be

(a) 0.5 *mV*

(b) 1* mV
*(c) 7

*mV*

(d) 3.5

*mV*

**Ques. **The half-life of the isotope _{11}Na^{24} is 15 hrs. How much time does it take for 7/8th of the sample of this isotope to decay

(a) 75 hrs

(b) 65 hrs

(c) 55 hrs

(d) 45 hrs

**Ques. **A silver and a copper voltmeters are connected across a 6 volt battery of negligible resistance. In half an hour, 1 gm of copper and 2 gm of silver are deposited. The rate at which energy is supplied by the battery will approximately be (Given ECE. of copper = 3.294 x 10^{–4} g/C & ECE of silver = 1.118 x 10^{–3} g/C)

(a) 64 watt

(b) 32 watt

(c) 96 watt

(d) 16 watt

**Ques. **In a double slit experiment, when sodium light of wavelength 5890Å is used, angular position of first bright fringe with respect to centre of screen is found to be 3 x 10^{–4} radian. Using a light source of another wavelength in place of this source, the angular position of the second bright fringe is found to be 4 x 10^{–4} radian. Wavelength of this light source is

(a) 5890Å

(b) 5480Å

(c) 4275Å

(d) 3927Å

**Ques.** The wavelength of light received from a milky way is 0.4% higher than that from the same source on earth. The velocity of milky way with respect to earth will be

(a) 5 x 10^{6} m/s

(b) 1.2 x 10^{6} m/s

(c) 0.2 x 10^{6} m/s

(d) 2 x 10^{6} m/s

**Ques. **In producing chlorine through electrolysis 100 KW power at 125 volt is being consumed. If the E.C.E. of chlorine is 0.367 x 10^{–6} kg/coul, then the mass of chlorine liberated per minute will be

(a) 16.3 x 10^{–4} kg

(b) 17.61 x 10^{–3} kg

(c) 18.2 x 10^{–3} kg

(d) 10^{–4} kg

**Ques. **For the four-bar linkage shown in the figure, the angular velocity of link AB is 1 rad/s. the length of link CD is 1.5 times the length of link AB. In the configuration shown, the angular velocity of link CD in rad/s is

(a) 3

(b) 3/2

(c) 1

(d) 2/3

**Ques. **Figure shows the schematic for the measurement of velocity of air (density = 1.2 kg/m) through a constant–area duct using a pitot tube and a water-tube manometer. The differential head of water (density = 1000 kg/m ) in the two columns of the manometer is 10mm. Take acceleration due to gravity as 2 9.8m/ s . The velocity of air in m/s is

(a) 6.4

(b) 9.0

(c) 12.8**
**(d) 25.6

**Ques.** A wave has velocity v in medium P and velocity 2v in medium Q. If the wave is incident in medium P at an angle of 30^{0}, then the angle of refraction will be

(a) 30^{0}

(b) 45^{0}

(c) 60^{0}

(d) 90^{0
}

**Ques. **A mass of 1kg is attached to two identical springs each with stiffness k = 20kN/m as shown in the figure. Under frictionless condition, the natural frequency of the system in Hz is close to

(a) 32**
**(b) 23

(c) 16

(d) 11

**Ques. **A disc of mass m is attached to a spring of stiffness k as shown in the figure. The disc rolls without slipping on a horizontal surface. The natural frequency of vibration of the system is

(a) | (b) | (c) | (d) |

**Ques. **A 1 kg block is resting on a surface with coefficient of friction µ = 0.1. A force of 0.8N is applied to the block as shown in figure. The friction force is

(a) 0 N

(b) 0.8 N

(c) 0.98 N

(d) 1.2 N

**Ques. **A solid shaft of diameter, d and length L is fixed at both the ends. A torque, T0 is applied at a distance, L/4 from the left end as shown in the figure given below

The maximum shear stress in the shaft is

(a) | (b) | (c) | (d) |

**Ques. **A uniform rigid rod of mass M and length L is hinged at one end as shown in the adjacent figure. A force P is applied at a distance of 2L/3 from the hinge so that the rod swings to the right. The reaction at the hinge is

(a) -P

(b) 0**
**(c) P/3

(d) 2P/3