Basic Physics Questions and Answers

1 For the logic circuit shown in the figure the truth table is LEA B C 0 1 100 1 1 B 000 1 0 1 010 1 0 A 0 1 3 A 1 0 C 1 B C 54B 2 A B C 0 0 0 1 0 1 4 A A 0 1 O 0 1 0 1 1 B 0 0 1 0 1 1 0 C 0 0 1 1 26 Two particles of separated by a distance of COM 24 kg mass will b A 3 1 5 Consider follo A In forw depletion decreas B Barrie amou The corn 1 Onl 3 Bo 28 28 Light phot The to

The gas in vessel is subjected to a pressure of 20 atmosphere at a temperature 27 C The pressure of the gas in a vessel after one half of the gas is released from the vessel and the temperature of the remainder is raised by 50 C is CBSE 1994 Similar EAMCET Engg 2000 a 8 5 atm b 10 8 atm c 11 7 atm d 17 atm

RS 52 5 52 22 Two current carrying conductor are placed on smooth 22 at an armes a fer cuir siger face was ren surface as shown in figure where a and a are acceleration and angular acceleration en after for conductor CD respectively 1 a 0 a 0 2 a 0 0 3 a 0 0 4 a 0 a 0 la CD for 1 a 0 a 0 2 a 0 0 3 a 0 a 0 4 a 0 a 0

1 A short electric dipole has a dipole moment c 16 x 10 C m The electric potential due to th dipole at a point at a distance of 0 6 m from th centre of the dipole situated on a line making a angle of 60 with the dipole axis is 1 41 0 9x10 Nm C 1 zero 2 50 V

A water film is formed between the two straight parallel wires each of length 1 cm kept at a separation of 0 5 cm Now the separation between them increased by 1 mm without breaking the water film The work done for this is surface tension of water 7 2 x 10 Nm 7 22 x 10 6 J 5 76x10 5 J 1 44 x 10 5 J

One end of a horizontal track of gauge and negligible resistance is connected to a capacitor of capacitance C charged to voltage Vo The inductance of the assembly is negligible The system is placed in a homogenous vertical magnetic field of induction B as shown in the figure A frictionless conducting rod of mass m and resistance R is placed perpendicularly onto the track The polarity of the capacitor is such that the rod is repelled from the capacitor when the switch is turned over What is the maximum velocity of the rod S X X A C B CV m B C B CV 2m B C V X X X E R X X X XBX B D l X 2B CV m B C B CV m 2B C

3 I MR X FR 1 Force 3 Linear impulse 4 Angular momentum A force is F is applied on the centre of a uniform circular disc of mass mand radius R which is kept on a smooth surface as shown in the figure The angular acceleration of the body about the centre of mass x c I BOLVE 1th gues 4 1 mR 441 2F m O 3 Zero 2 F 2mR 2F mR 3 Zero 4 4 In the question 3 acceleration of centre of mass of the disc will be 2 FRX2 MRY 4 F 2m 4 E MR m 3 In th the 1

Two particles execute SHM of same ampli 15 3 cm with same period along the same line about the same equilibrium position If phase TL then find out the maximum distance 3 between these two difference is 1 45 cm 2 22 5 cm 3 15 3 cm sufficient 1 3

A ball of mass 0 25 kg attached to the end of a string of length 1 96 m is moving in a horizonta circle The string will break if the tension is more than 25 N What is the maximum speed with which ball can be moved A 14 ms B 3 ms C 3 92 ms D 5 ms

Loy cart is tied to the end of an unstretched string of length A When revolved the toy cart ves in horizontal circle with radius 22 and time period T If it is speeded until it moves in izontal circle of radius 32 with period T relation between T and T is Hooke s law is yed 2 T T 3 B T T 2 1 T C T D T 3 T

A box of mass m is pressed against but is not attached to an ideal spring of force constant k and negligible mass compressing the spring a distance x After it is released the box slides up a frictionless incline as shown in the figure and eventually stops If we repeat this experiment but instead compress the spring a distance of 2x k m 0000000 Smooth Smooth Select one a just as it moves free of the spring the box will have twice as much kinetic energy as before Ob just as it moves free of the spring the box will be traveling four times as fast as before O c just as it moves free of the spring the box will be traveling twice as fast as before d the box will go up the incline twice as high as before

Consider an imaginary three dimensional surface with base as a regular hexagon as shown in figure Walls are perpendicular to the base An infinite wire carrying uniform linear charge density is placed along one of the edges The flux of electric field through the rectangular face ABCD as shown in figure is A A Zero B C h 350 h 12 B D None of these h

The capacitance of the reversed biased p n junction Answer A Increases as the reversed bias is decreased B Increases as the reversed bias is increased C Depends on the reverse saturation current D None of these

Two stones one of mass m and the other of mass 2m are thrown directly upward with the same velocity at the same time from ground level and feel no air resistance Which statement about these stones is true Select one O a At its highest point the heavier stone will have twice as much gravitational potential energy as the lighter one because it is twice as heavy O b At their highest point both stones will have the same gravitational potential energy because they reach the same height c The heavier stone will go twice as high as the lighter one because it initially had twice as much kinetic energy O d Both stones will reach the same height because they initially had the same amount of kinetic energy Check

A train approaching a platform sounds a frequency 500 Hz lasting for duration of 20s If a man at the platform observes the frequency of the whistle to be 550 Hz Find the duration At for which he hears the sound of the whistle velocity of sound in air 330m s Then At is Your Answer 10 Answer 18 18 S

Six identical point charges each of charge Q are placed at vertices of hexagon of side length a The hexagon is placed in horizontal XY plane A charged particle q m is found to be at stable equilibrium at point 0 0 d Electrostatic force acting on charged particle q m is 3Qqd 4 a d 2 Qqd a 3Qqd 2 a d 2 Read Less Qqd

A solid shaft is transmitting 2 MW at 270 r p m Determine the diameter of the shaft if the maximum torque transmitted exceeds the mean torque by 20 Take the maximum allowable shear stress as 72 MPa

3 An n type Si material has a resistivity of p 0 65 0 cm i If the electron mobility is Un 1250 cm V s what is the concentration of donor atoms ii Determine the required electric field to establish a drift current density of J 160 A cm 2 2

24 A Capacitor of capacitance C is charged with a battery of potential V and then disconnected Now a charge Q is given to negative plate then potential difference between the plates is 1 V 2 V 3 V 4 V C 2Q C

Which statement about hydroelectric power plant is wrong Answer A Efficiency of hydroelectric power plant does not reduce with age B Its construction coast is very high and takes a long time for erection C It is very neat and clean plant because no smoke or ash is produced D Meeting rapidly changing load demands is not possible in hydroelectric power plant

A ball of mass m is moving with velocity v A player kicked it in direction perpendicular to initial direction maintaining same speed The impulse applied on the ball is 1 Zero 2 mv 3

Three small balls of the same mass white w green g and blue b are fixed by weightless rods at the vertices of the equilateral triangle with side 1 The system of balls is placed on a smooth horizontal surface and set in rotation about the centre of mass with period T At a certain instant the blue ball tears away from the frame Determine the distance L between the blue and the green ball after the time T 4 2 3 1 3 1 C 3 A 2 3 4 B 3 D 32 x 3 12 4

Answer A Voltage source remains the same B same Current sources remain the C Both voltage and current source remain the same

In a platinum resistance thermometer the resistances of the wire at ice point and steam point are of 42 and 4 25 2 respectively When the thermometer is kept in a hot water bath whose temperature is not known the resistance of the wire is found to be 4 5 2 The temperature of the hot water bath is A 150 C B 100 C C 300 C D 350 C E 200 C

11 Find the equivalent resistance across AB 1 10 669 2 202 3 302 4 42 Be 20 202 20 252 11 AB 1 1 2 202 3 302 4 4 2 20 201 H 20 20 Lumin 20

7 Calculate the percent efficiency of a CFL if it produces 50 J of light energy while using 75 J of electrical energy K U 4 Given 1 Statement 1 Formula s Equation s and Answer 2

The function of oil in a transformer is Answer to provide insulation and A cooling to provide protection against B lightning to provide protection against C short circuit

A bird is sitting in a wire cage hanging from the spring balance Let the reading of the spring balance be W If the bird flies about inside the cage the reading of the spring balance is W Which of the following is true Question Type Single Correct Type 1 2 3 W W2 W W2 W W2

3 An electron is accelerated from rest through a potential difference of V volt If the de Broglie wavelength of the electron is 1 227 10 nm the potential difference is a 10 V c 10 V b 10 V d 104 V NEET 2020

are The commercial sources of energy Answer A solar wind and biomass fossil fuels hydropower and B nuclear energy C wood animal wastes and agriculture wastes

B A charge Q is distributed over two concentric spheres of radii r and R R r such that th Q R r surface charge densities are equal Show that the potential at the common centre is 4 R r

An infinite number of charges each of charge 1 C are placed on x axis with co ordinates X m 1 2 4 8 If a charge 2 C is placed at origin then the net force on 2 C charge is O 18000 N O 24000 N O 48000 N O 72000 N

A motal sphere having radus is charged to potential V Sphere is enveloped by thin conducting shell of radius 4r Shell and sphere are thone connected by a conducting wire Then Electric field near the outer surface of shell is Field inside the shell szero Potential of the shell is D Potental of the shelis V 10

can t understand solution why middle resistance is not ed in charging of capacitor what is t1 when switch is clos d And how to find it and t2 when switch is open iss typ Ke other questions kaise solve karega 5 In the circuit shown when the switch is closed 5 the capacitor is charged with time constant T and when switch is open then capacitor discharge with time constant t then T T is C 1 1 2 1 2 E R AMM R AAAA S 3 20

31 The position x of a partiale ver X 6in100m 8in100 ENTERTA The Mon The particle is 1 Not simple harmonic 2 Simple harmonic with amplitude 10 ure 3 Simple harmonic with amplitude 14 unit 4 Simple harmonic with amplitude 7 una

Draw a circuit diagram with a single cell battery a switch and a lamp Connect an ammeter to the circuit to measure the current through the load 2

Blue eye colour is recessive to brown eye colour A brown eyed man whose mother was blue eyed marries a blue eyed woman The children will be B X 1 blue eyed and 1 brown eyed All brown eyed All blue eyed

A very long solenoid having n turns per unit length is shown in the figure The magnetic field at point P is f 2 3 Correct Answer 4 Your Answer 2 Status incorrect Honl Zero Honl 2 2 Honl 2 1 2 1 0 P

Two infinite linear charges have linear charge densities A and are arranged as shown They are parallel to Z axis Then 0 X At any point on Y axis field is along negative X axis Potential at all point on Y axis is zero Electric field at origin is zero 27 Electric field at origin is RE i

Hip circle lies initially in the magnetic meridian it shows an angle of dip 8 at a place The dip circle is rotated ough an angle a in the horizontal plane and then its shows an angle of dip 8 Hence tan 8 tan 8 tions cos a 1 cos a 1 tan a is

Y Two sound sources emitting plane waves separated by 12 meter vibrates according to law y 3sin 4rt and y 4sin 4rt respectively A point in the medium is at a position 8 m from first source and 4 m from second on the line joining two sources The sources send out waves of velocity 32 m s Find equation of the motion of the particles y y are in centimeter and t is in second 1 1 YR 5 sin 4 t tan 2 YR 5 sin 4 t tan 3 YR 5sin 4rt tan 4 YR 5sin 4rt tan A light 4 3 3 4 paupat 10 4 3 4

Three forces shown in figure act on a body simultaneously What will be the magnitude in newton of smallest additional force to make net force along east direction North West 3N SN 37 4N South East

Design the circuit of Fig 5 21 that is determine the values of R and R so that the transistor operates at I 0 4 mA and V 0 5 V The NMOS transistor has V 0 7 V MC 100 A V L 1 m and W 32 m Neglect the channel length modulation effect i e assume that 0 VDD 2 5 V Ip ID RD Rs VD VSS 2 5 V

0 A uniform rod AB has mass 2m and length 26 kept on a smooth horizontal plane Rod AB is orthogonaly connected to a taut string whose other end has a particle of mass m If particle is given initial velocity v perpendicular to string then just after giving velocity mark the INCORRECT options A Tension in string is 2m 90 B Acceleration of rod is A m 20 2m B SAYATHE C Angular acceleration of rod is 21 D From the frame of center of mass of rod Particle moves in a circular path

A smooth Tixed rod is inclined at an angle 30 to horizontal There is a fixed charge Q at the bottom of roc There is a bead of mass m having charge q that can slid freely on the rod At equilibrium height of bead is h 2 Time period of oscillation of bead is q O 30 70 LSI 1g O2T h O 2 2g h 2

If two coherent sources are placed at a distance 3A from each other symmetric to the centre of the circle as shown in the figure then number of fringes shown on the screen placed along the circumference is 32 Question Type Single Correct Type 1 16

Hg 25 A liquid X of density 3 36 g cm is poured in a U tube which contains Hg pH 13 6 g cm Another liquid Y is poured in left arm with height 8 cm Upper levels of X and Y are same What is density of Y 8 cm U 10 cm 1 0 8 g cc 2 1 2 g cc 3 1 4 g cc 26 Mercury is a convenient liquid to use in a barometer because 1 it is a metal 3 it expands little with temperature 4 1 6 g cc 2 it has a high boiling point 4 it has a high density

If Z is a complex number then mod Z means A None of these B Its angle between real axis and line joining the complex number with origin C Length of vector from origin to that point in a complex plane D It is a always a negative number

A parallel plate capacitor is charged to a potential difference of 50 V It is discharged through a resistance After 1 second the potential difference between plates becomes 40 V Then Question Type Single Correct Type 1 2 3 4 Fraction of stored energy after 1 second is 16 5 Potential difference between the plates after 2 seconds will be 32 V Potential difference between the plates after 2 seconds will be 20 V Fraction of stored energy after 1 second is 4 5

Consider a uniform spherical planet of mass M and radius R Two parallel tunnels are dug perpendicular distance symmetrically from centre A particle is to be thrown from the starting 3R 5 one tunnel such that it enters in another tunnel without making collision with tunnel wall and continue its motion as shown in figure Tunnels are friction less and particle just fits inside the tunnel Conside the planet to be at rest Choose the correct options R 3R 3R 5 5 A Speed with which the particle is to be thrown at starting of one tunnel is B Minimum speed of particle during entire motion is GM 9R 4R C Maximum height achieved by the particle during subsequent motion is 5 GM R