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Physics Questions and Answers October 04, 2022

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Two persons of masses 55 kg and 65 kg respectively, are at the opposite ends of a boat. The length of the boat is 3.0 m and weighs 100 kg. The 55 kg man walks up to the 65 kg man and sits with him. If the boat is in still water the centre of mass of the system shifts by (a) 3.0 m (c) zero (b) 2.3 m (d) 0.75 m

A particle executing S.H.M. has amplitude 0.01m and frequency 60 Hz. The maximum acceleration of the particle is (a) 144 ms (c) 80 ms (b) 120 ms (d) 60 ms

A potentiometer circuit is set up as shown. The potential gradient, across the potentiometer wire, is k voltcm and the ammeter, present in the circuit, reads 1.0 A when two way key is switched off. The balance points, when the key between the terminals (i) 1 and 2 (ii) 1 and 3, is plugged in, are found to be at lengths 7, cm and 1 cm respectively.

In the Youngs doubleslit experiment, the intensity of light at a point on the screen where the path difference is is K, ( being the wave length of light used). The intensity at a point where the path difference is 24, will be (a) K (c) K2 (b) K4 (d) Zero

A capacitor is charged by using a battery which is then disconnected. A dielectric slab is then slipped between the plates, which results in (a) Reduction of charge on the plates and increase of potential difference across the plates (b)Increase in the potential difference across the plate, reduction in stored energy, but no change in the charge

Eight drops of mercury of equal radii possessing equal charges combine to form a big drop. Then the capacitance of bigger drop compared to each individual small drop is (a) 8 times (b) 4 times (c) 2 times (d) 32 times

The input resistance of a silicon transistor is 100 W. Base current is changed by 40 4 which results in a change in collector current by 2 mA. This transistor is used as a common emitter amplifier with a load resistance of 4 KQ. The voltage gain of the amplifier is (a) 2000 (c) 4000 (b) 3000 (d) 1000

Separation between the plates of a parallel plate capacitor is a and the area of each plate is A. When a slab of material of dielectric constant and thickness t(t

a particular system, the unit of length, mass and time are chosen to be 10 cm, 10 g and 0.1 s respectively. The unit of force in this system will be equivalent to (a) 0.1 N (c) 10 N (b) 1 N (d) 100 N

A mass of 2.0 kg is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes a simple harmonic motion. The spring constant is 200 Nm. What should be the minimum amplitude of the motion so that the mass gets

The wavelength of an electron and a of a photon are of same energy E are related by 2013 (a) (0) (c) ap (d) The

The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and Care as given. The logic circuit gate is B (a) OR gate (b) NOR gate (c) AND gate (d) NAND gate 4 5 to

Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX axis is (a) 3mr (b) mr (c) 4mr (d) mr

A transverse wave is represented by y A sin (t kx). For what value of the wavelength is the wave velocity equal to the maximum particle velocity 2 (b) (c) 2 (d) A

A particle has initial velocity (21 3) and acceleration (0.31 02). The magnitude of velocity after 10 seconds will be (a) 92 units (c) 5 units (b) 52 units (d) 9 units

A solid cylinder and a hollow cylinder both of the same mass and same external diameter are released from the same height at the same time on an inclined plane. Both roll down without slipping. Which one will reach the bottom first (a) Both together (b) Solid cylinder (c) One with higher density (d) Hollow cylinder

The temperature at which the speed of sound becomes double as was at 27C is (a) 273 C (c) 927 C (b) 0 C (d) 1027C

Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current. The force of attraction per unit length between the two wires is (a) 2 x 10 Nm (c) 5 x 108 Nm (b) 2 108 Nm (d) 107 Nm

Light of wavelength 5000 falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectrons emitted will be (a) 0.58 eV (c) 1.24 eV (b) 2.48 eV (d) 1.16 eV

A boy standing at the top of a tower of 20m height drops a stone. Assuming g 10 ms2, the velocity with which it hits the ground is (a) 10.0 ms (c) 40.0 ms (b) 20.0 ms (d) 5.0 ms

For this problem, you may assume that the operational amplifier is ideal. Using the circuit below, find the unknown voltage Vx, given R R R3 2k Ohms and V 2V. R Answer Vx R VOUT Write your answer in volts.

2 ww11 Answer R A04 Vin Vout For the operational amplifier circuit shown, what value must R1 be in kilohms in order to set the voltage gain to 3.3 VV Assume that the opamp is ideal, and use R2 13.8kQ.

Two sources of sound placed close to each other are emitting progressive waves given by y, 4 sin 600 t and y 5 sin 608 t. An observer located near these two sources of sound will hear (a) 4 beats per second with intensity ratio 25 16 between waxing and waning. (b) 8 beats per second with intensity ratio 25 16 between waxing and waning (c) 8

Through repeated applications of Nortons Theorem, find the value of the Norton equivalent resistance for the circuit shown in kilohms. Use 1 15.7mA, R1 10.3k2, R2 36.5k, R3 12k and R4 16.8k.

The work done in turning a magnet of magnetic moment M by an angle of 90 from the meridian, is n times the corresponding work done to turn it through an angle of 60. The value of n is given by (a) 2 (b) 1 (c) 0.5 (d) 0.25

For the operational amplifier circuit shown, what is the output voltage if V1 3.417V, V2 3.142V and V3 3.604V Assume that the opamp is ideal, and use R1 1.6k02, R2 4.3k0, R3 1.1k0 and RF 1.1k0.

For the circuit shown, what is the value of the voltage V in volts Use V1 5.5V, V2 0.6V, R1 2.4k02, R2 1.7k2, and R3 15.2k0.

What is the voltage gain in VV from the V3 input to the output for the operational amplifier circuit shown Assume that the opamp is ideal, and use R1 3.3kQ, R2 4.7k0, R3 3.7k and RF 41.5kQ.

The angle between the two vectors A 3 4) 5k and B 3 4 5k will be 2001, 1994 (a) zero (c) 90 (b) 45 (d) 180

For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is (a) 2,(b) 2 (c) 2 (d) 2

Suppose the charge of a proton and an electron differ slightly. One of them is e, the other is (e Ae). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then Ae is of the order of Given mass of hydrogen m 1.67 10 kg (a) 10 C (c) 10 C 27 h

A conducting circular loop is placed in a uniform magnetic field, B 0.025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mm s. The induced e.m.f. when the radius is 2 cm, is (a) 2 (c) FuV (b) nuv (d) 2V

An electron changes its position from orbit n 2 to the orbit n 4 of an atom. The wavelength of the emitted radiations is (R Rydbergs constant) (a) (d) 16R16 16 16 3R 5R 7R

For angles of projection (45 0), the horizontal projectile are in the ratio of (a) 13 (c) 21 of a projectile (45 0) and ranges described by the (b) 12 (d) 11

What are the magnitudes and directions of each of the following position vectors When reporting a direction, make sure you give the amount of rotation, the direction of rotation, and the starting point for the rotation. a. Ax 15.0 m, Ay 18.0m b. Bx 75 m, By 85m c. Cx 3.58 m, Cy 2.80 m

A wind with speed 40 ms blows parallel to the roof of a house. The area of the roof is 250 m. Assuming that the pressure inside the house is atmosphere pressure, the force exterted by the wind on the roof and the direction of the force will be (p 1.2 kgm) (a) 4.8 x 10 N, upwards (c) 2.4 x 10 N, downwards air (b) 2.4 x 10 N, upwards (d) 4.8 10 N,

There is an electric field E in xdirection. If the work done on moving a charge of 0.2 C through a distance of 2 Im along a line making an angle 60 with xaxis is 4J, then what is the value of E (a) 3 NC (c) 5 NC (b) 4 NC (d) 20 NC

A small signal voltage V(t) V, sin oot is applied across an ideal capacitor C (a) Current I (t), lags voltage V(t) by 90. (b) Over a full cycle the capacitor C does not consume any energy from the voltage source. (c) Current I (t) is in phase with voltage V(t). (d) Current I (t) leads voltage V(t) by 180.

Atomic weight of Boron is 10.81 and it has two isotopes Band B Then the ratio 5B 5B in nature would be (a) 1981 (c) 15 16 (b) 1011 (d) 81 19

The force F acting on a particle of mass m is indicated by the forcetime graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is,24 Ns (a) (c) 12 Ns F(N) 63 0 2 8 (b) 20 Ns (d) 6 Ns

if the radius of a star is R and it acts as a black body, what would be the temperature of the star, in which the rate of energy production is Q 2012 (a) Q4Ro 2 (b) (Q4R0) (c) (4RQ0)4 (o stands for StefanS constant) 12 (d) (Q4R0)4

Charges q and q are placed at points A and B respectively which are a distance 2L apart, C is the midpoint between A and B. The work done in moving a charge Q along the semicircle CRD is R (a) (b) (c) (d) qQ 2 L qQ qQ qQ 4L A C B D

A capacitor has capacity C and reactance X. If capacitance and frequency become double, then reactance will be (a) 4X (c) X4 (b) X2 (d) 2X

Fission of nuclei is possible because the binding energy per nucleon in them (a) increases with mass number at low mass numbers. (b) decreases with mass number at low mass numbers. (c) increases with mass number at high mass numbers. (d) decreases with mass number at high mass numbers.

The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is (a) 4 ms upwards (b) 4 ms2 downwards (c) 14 ms upwards (d) 30 ms downwards

A parallel plate condenser with oil between the plates (dielectric constant of oil K 2) has a capacitance C. If the oil is removed, then capacitance of the capacitor becomes (a) 2c (b) 20 USUIN

A mixture consists of two radioactive materials A and A, with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A, and 160 g of A. The amount of the two in the mixture will become equal after (a) 60 s (c) 20 s (b) 80 s (d) 40 s

A ring is made of a wire having a resistance R 12 2. Find the points A and B as shown in the figure, at which a current carrying conductor should be connected so that the resistance R of the subcircuit between these 8 points is equal to (a) 112 (b) (d) 112 NIT 8 W WIT

A person is six feet tall. How tall must a vertical mirror be if he is able to see his entire length 2000 (a) 3 ft (c) 7.5 ft (b) 4.5 ft (d) 6 ft

The most penetrating radiation of the following is (a) gammarays (b) alpha particles (c) betarays (d) Xrays

An ideal carnot engine, whose efficiency is 40 receives heat at 500 K. If its efficiency is 50, then the intake temperature for the same exhaust temperature is (a) 600 K (c) 800 K (b) 700 K (d) 900 K

A student measures the terminal potentia difference (V) of a cell (of emf E and internal resistance r) as a function of the current (I) flowing through it. The slope and intercept, of the graph between V and I, then respectively, equal (a) r and E (b) rand E (c) E and r (d) E and r

A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point 15 cm from the lens on the opposite side. If the lens is removed the point where the rays meet will move 5 cm closer to the lens. The focal length of the lens is (a) 10 cm (c) 30 cm (b) 20 cm (d) 5 cm

A point 22 caliber gun fires a bullet at a speed of 1200 feet per second. If a .22 caliber gun is fired straight upward into the sky, the height of the bullet in feet is given by the equation h = - 16t 2 + 1200t, where t is the time in seconds with t = 0 corresponding to the instant the gun is fired. How long is the bullet in the air?

16 Pure Si at 500K has equal number of electron (n) and hole (n.) concentrations of 1.5 10 m. Doping by indium increases n, to 4.5 x 10 m. The doped semiconductor is of (a) ntype with electron concentration n 5 10 m (b) ptype with electron concentration n 2.510 m (c) ntype with electron concentration n 2.5 x 10 m d) ptype having electron

Two particles A and B, move with constant velocities V and V. At the initial moment their position vectors are and 2 respectively. The condition for particles A and B for their collision is (a) r. V F. V (b) r x V F X V (c) F F V V VV (d). VVl FF

The molar specific heats of an ideal gas at constant pressure and volume are denoted by C and C,,respectively. If y and R is the universal gas constant, Cy then C is equal to 2013 (a) R (y1) (y1) R (b) (c) YR (d) y 1Y

For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index (a) lies between2 and 1 (c) is less than 1 (b) lies between 2 and2 (d) is greater than 2

Two simple harmonic motions with the same frequency act on a particle at right angles i.e., along x and y axis. If the two amplitudes are equal and the phase difference is 12, the resultant motion will be (a) a circle (b) an ellipse with the major axis along yaxis (c) an ellipse with the major axis along xaxis (d) a straight line inclined at 45 to

Three resistances P, Q, R each of 20 and an unknown resistance S form the four arms of a Wheatstone bridge circuit. When a resistance of 60 is,connected in parallel to S the bridge gets balanced. What is the value of S (a) 302 (c) 1 (b) 6 (d) 20

In Youngs double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths 12000A and 2 10000. At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other 2013 (a) 6 mm (c) 3 mm (b)

A circular platform is mounted on a frictionless vertical axle. Its radius R 2 m and its moment of inertia about the axle is 200 kgm. It is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the speed of 1 ms relative to the ground. Time taken by the man to complete one revolution is (a) s 3 (b)

A particle executes simple harmonic oscillation with an amplitude a. The period of oscillation is T. The minimum time taken by the particle to travel half of the amplitude from the equilibrium position is (a) T8 (c) T2 (b) T12 (d) T4

A charged particle of charge q and mass m enters perpendicularly in a magnetic field B. Kinetic energy of the particle is E then frequency of rotation is (a) qB m qB (b) 2m qBE (c) (d) 2m qB 2E

The deBroglie wavelength of neutron in thermal equilibrium at temperature Tis 30.8 (a) A VT 3.08 T 0.308 (b) A (c) A (d) A T 0.0308

The ratio of radii of gyration of a circular ring and a circular disc, of the same mass and radius, about an axis passing through their centres and perpendicular to their planes are NEET Kar. 2013, 2008 (a) 21 (c) 32 (b) 12 (d) 21

A wave in a string has an amplitude of 2 cm. The wave travels in the ve direction of x axis with a speed of 128 msec and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is (a) y (0.02) m sin (15.7x 2010t) (b) y (0.02) m sin (15.7x 2010t) (c) y (0.02) m sin (7.85x 1005t) (d) y (0.02) m sin

If a long hollow copper pipe carries a current, then magnetic field is produced (a) inside the pipe only (b) outside the pipe only (c) both inside and outside the pipe (b) no where

Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be (a) 14 (c) 11 (b) 12 (d) 15

The motion of a particle along a straight line is described by equation x812tt where x is in metre and t in second. The retardation of the particle when its velocity becomes zero, is (b) zero (a) 24 ms 6 ms (c) (d) 12 ms

Which of the following statement is correct (a) Photocurrent increases with intensity of light (b) Photocurrent is proportional to the applied voltage (c) Current in photocell increases with increasing frequency (d) Stopping potential increases with increase of incident light

A ball is dropped from a high rise platform at t 0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with a speed v. The two balls meet at t 18s. What is the value of v (take g 10 ms) (a) 75 ms (c) 40 ms (b) 55 ms (d) 60 ms

In a rocket a seconds pendulum is mounted. Its period of oscillation decreases when the rocket 1991 (a) comes down with uniform acceleration (b) moves round the earth in a geostationary orbit (c) moves up with a uniform velocity (d) moves up with uniform acceleration

If theta1, and theta2, be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip 0 is given by (a) tan0 tan0, tan0 (c) tan0 tan0 tan0 (b) cot0 cot0,cot0 (d) cot0 cot0, cot0,

In Rutherford scattering experiment, what will be the correct angle for ascattering for an impact parameter, b0 (a) 90 (c) 0 (b) 270 (d) 180

A particle moves with a velocity v 6 4) 3k ms under the influence of a constant force F 201 15 5k N. The instantaneous power applied to the particle is 2000 (a) 45 Js (c) 25 Js (b) 35 Js (d) 195 Js

The escape velocity on the surface of earth is 11.2 kms. What would be the escape velocity on the surface of another planet of the same mass but 14 times the radius of the earth (a) 22.4 kms (c) 5.6 kms (b) 44.8 kms (d) 11.2 kms

Two identical charged spheres suspended from a common point by two massless strings of lengths I, are initially at a distance d (d ) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then v varies as a function of the

Two projectiles are fired from the same point with the same speed at angles of projection 60 and 30 respectively. Which one of the following is true (a) Their maximum height will be same (b) Their range will be same (c) Their landing velocity will be same (d) Their time of flight will be same

The electric field in a certain region is acting radially outward and is given by E Aa. A charge contained in a sphere of radius a centred at the origin of the field, will be given by (a) A a (c) Aa (b) 4 Aa (d) 4 Aa 3 2

A stone is dropped from a height h. It hits the ground with a certain momentum P. If the same stone is dropped from a height 100 more than the previous height, the momentum when it hits the ground will change by (a) 68 (c) 200 (b) 41 (d) 100

As per the diagram, a point charge q is placed at the origin O. Work done in taking another point charge. Q from the point 4 coordinates (0, a) to another point B coordinates (a, 0) along the straight path AB is (a) zero (b) (901) a 4 9Q 1 a (c) (99, )2 , (d) (1901). Za a 0 B

Certain quantity of water cools from 70C to 60C in the first 5 minutes and to 54C in the next 5 minutes. The temperature of the surroundings is (a) 45C (c) 42C (b) 20C (d) 10C

The electric and magnetic field of an electromagnetic wave are (a) in opposite phase and perpendicular to each other (b) in opposite phase and parallel to each other (c) in phase and perpendicular to each other (d) in phase and parallel to each other.

The half life of a radioactive nucleus is 50 days. The time interval (tt.) between the time when of it has decayed and the time tl when of it had decayed is (a) 30 days (b) 50 days (c) 60 days (d) 15 days

A car of mass 1000 kg negotiates a banked curve of radius 90 m on a frictionless road. If the banking angle is 45, the speed of the car is (a) 20 ms (c) 5 ms (b) 30 ms (d) 10 ms

One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 53, the final temperature of gas will be (a) (T4) K (b) (T2.4) K (c) (T2.4) K (d) (T4) K

A wire of resistance 12 ohms per meter is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite points, A and B as shown in the figure, is (a) 30 (c) 6 (b) 6 (d) 0.6 B

What is the respective number of a and Bparticles emitted in the following radioactive decay 200X, X90 168Y30 (a) 6 and 8 (c) 8 and 8 (b) 6 and 6 (d) 8 and 6

A body of mass 1 kg is thrown upwards with a velocity 20 ms. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction (g 10 ms) (a) 30 J (c) 10 J (b) 40 J (d) 20 J

Two vessels separately contain two ideal gases A and B at the same temperature. The pressure of A being twice that of B. Under such conditions, the density of A is found to be 1.5 times the density of B. The ratio of molecular weight of A and B is 3 (b) 2 (a) IHINNIM (d).

A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of d diameter in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively (a) fand 4 3f (b) and 4 (c) fand 2 31 4 (d) and 2

A zener diode, having breakdown voltage equal to 15V, is used in a voltage regulator circuit shown in figure. The current through the diode is (a) 10 mA 20V www 25092 15V (b) 15 mA 1ks2,(c) 20 mA (d) 5 mA

On a frictionless surface a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle 0 to its initial direction and has a speed. The second blocks speed after the collision is 3 (b). 3 (c) V 22 (d) 2v2 3 V

The molar specific heat at constant pressure of an ideal gas is (72) R. The ratio of specific heat at constant pressure to that at constant volume is (a) 87 (c) 97 (b) 57 (d) 75

A thin prism of angle 15 made of glass of refractive index 1.5 is combined with another prism of glass of refractive index u 1.75. The combination of the prism produces dispersion without deviation. The angle of the second prism should be (a) 7 (c) 12 (b) 10 (d) 5

A particle starts simple harmonic motion from the mean position. Its amplitude is A and time period is T.What is its displacement when its speed is half of its maximum speed (a) A (b) A (d)

In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will 40 (b) be zero (c) flow from B to A (d) flow from A to B 192 B 402 302 (a) flow in the direction which will be decided by the value of V

A common emitter amplifier has a voltage gain of 50, an input impedance of 10092 and an output impedance of 2002 The power gain of the amplifier is (a) 500 (c) 1250 (b) 1000 (d) 50

Two force vectors are drawn in the Fig.1 below. 1) Find the resultant force FR FF approximately by graphical method. 2) Find the resultant force FR FF approximately by graphical method. Fig.1 F 40 b Problem 2 (20 points) 20 F50 tb Using the component method in Problem 1 to Determine 1) the magnitude of resultant force FR F1 F. 2) Its