Basic Physics Questions and Answers

0 An electron in a hydrogen atom falls from an orbit with principal quantum number n 2 to n 1 What is the wavelength X of the emitted radiation where R denotes the Rydberg constant A B A C A 4 3R 4 5R 3R 4 D A 4 3R

A isothermally B adiabatically its compressibility is 1 p its compressibility is y p C at constant pressure its room mean square speed remains const D adiabatically its compressibility is 1 yP

9 A body of mass 0 5 kg travels in a straight line with velocity v kx 2 where k 5 m 1 2 s The work done by the net force during its displacement from S x 0 to x 2 m is a 20 J b 40 J c 50 J d 100 J

6 Two thin metallic strips carrying current in the direction shown cross each other perpendicularly without touching but being close to each other as shown in the figure The regions which contain some points of zero magnetic field are a I and II b I and III c I and IV d II and III I II III IV

8 A steel wire of length 1 meter is under a tension of 10 newtons The speed of the transverse wave excited in this wire is v The wire is replaced by another steel wire of the same length but half the diameter What should be the tension in the replaced wire so that the speed of the wave stays the same A 40 N B 20 N C 5 N D 2 5 N

Assume that you are sitting in a car You see a person in the rear view mirror of radius of curvature 2m running towards you at t 0 If person is running with velocity 5m s and it is at 9m distance from mirror at this instant The average velocity of the image of man in first second is 1 20 cm s 3 10 cm s 2 25 cm s 4 30 cm s

The surface of metal with work function o is illuminated by electromagnetic radiation whose electric field component is E a 1 cosot cosoot Then maximum kinetic energy of photoelectron liberated from surface is 1 3 h 2 18 h wo 2 2 4 hoo 2r h w wo 2r

Four long straight wires are parallel to each other and their cross section form corners of a square Each side of the square is 2 2 cm as shown in the figure If each wire carries a current of 8 0 A in the direction shown in the figure determine the magnitude of the total magnetic field in mT at P the center of the square 2 2 cm 2 2 cm P

Two vessels of the same volume contain the same ideal gas at same temperature If the pressu in the vessels be in the ratio of 1 2 then A the ratio of the average kinetic energy is 1 2 B the ratio of the root mean square velocity is 1 1 C the ratio of the average velocity is 1 2 D the ratio of number of molecules is 1 2

d The motion has no 54 The displacement of a particle is given by x t 2 where x is in metre and t in second The distance covered by the particle in first 4 seconds INCERT Exempl Y 4 m c 12 m 8 m f d 16 m ftor hailing out falls 50 m without tes at

A puck moving at 2 0 ms on an air hockey table collides with a stationary identical puck head on The motions of the two pucks are in the same line The total kinetic energy of the pucks is halved after the collision Find coefficient of restitution O A O OB 0 2 OC 0 5 OD 0 7

A uniform plank of mass m free to move in horizontal direction is placed on the top of a solid cylinder of mass 2m and radius R The plank is attached with one end of a mass less spring of force constant k and the other end of spring is fixed with a wall as shown in fig The plank is shiftily displaced towards spring and released There is no slipping any where then R is v is my x v m C k 88888 2m Horizontal surface A Total energy of the system when compression is spring is x and velocity of plank B Angular frequency of oscillation is 4k 7m

A block of mass 2 kg is attached to a spring of spring constant 200 Nm 1 oscillates without friction over a smooth horizontal surface The block is displaced by 10 cm from equilibrium position and released What is maximum acceleration of block 1 1 ms 3 0 5 ms NCERT Pg 348 2 2 ms 4 1 5 ms

A beam of electrons and protons are ejected parallel in the same di rection What will be the nature of force between them Repulsive Attractive Neither repulsive nor attractive Will electrostatic force act on the particles If yes what will be the individual electric and magnetic fi eld and the resultant force

Two moving coil galvanometers N number of turns in the coil 30 A area of the coil 3 6 10 m B 0 25 T N 42 M and M have the following particulars A 1 8 x 10 m B 0 50 T The spring constants are identical for the two meters Determine the ratio of current sensiti deflection per unit current of M and M

Yourself An a particle is travelling at right angles to magnetic field with a speed of 6 x 105 m s The strength of the magnetic field is 0 2 T Calculate 1 Force on the x particle ii Acceleration of the a particle

A charged particle is moving away from a uniformly charged infinite wire along a direction perpendicular to it Initially the particle is at a distance L from the wire moving with a velocity u When it is at a distance 2L its velocity is found to be 2u What will be the velocity of the particle when it is at a distance 4L from the wire A 6u B Tu C 8u D 9u

If the moment of inertia of a disc about an axi which is along its diameter is then the momen of inertia about the axis passing through its centr and perpendicular to plane is NCERT Pg 165 1 2 1 2 LA

5 A 2 0 m straight wire carrying a current of 0 60 A is oriented parallel to a uniform magnetic field of 0 50 T What is the magnitude of the magnetic force on it A zero B 0 15 N C 0 30 N D 0 60 N

A very long uniformly charged wire oriented along the axis of a circle of radius R rests on its center with one of the ends The linear charge density on the wire is 2 Evaluate the flux of vector E across the circle area 2 R

We make helium gas of 2 g to go through the thermal cycle shown in the figure The lowest temperature of the gas in the cycle is 17 C the highest is 127 C and the temperature is equal at points A and B R Universal gas constant P Por D B A the temperature of A B is 320 K B the temperature at A B is 328 K C net work done by the gas during a cycle is 32 R D net work done by the gas during a cycle is 8 R

0 A 2 0 1 resistor is in parallel with a series combination of 4 0 01 6 0 0 and 12 01 resistors What is the equivalent resistance of this system A 24 f B 4 0 f C 1 8 f Porchel D 0 7 2 7 What is the 1 E44

A body cools from 67 C to 37 C If this takes time when the surrounding temperature is 27 C t what will be the time taken if the surrounding temperature is 7 C A 21 B 1 3 C 1 2 D 1 4

A moving coil galvanometer when shunted with a resistance of 5 2 gives a full scale deflection for 250 mA and when a resistance of 1050 is 2 connected in series it gives a full scale deflection for 25 volt Find the resistance of the galvanometer and the current required to produce a full scale deflection when it is used alone

4 A particle executes SHM has maximum J speed of 20 cm s 1 and maximum acceleration of 40 cm s 2 The period of oscillation is NCERT Pg 361 1 TS 3 Is S 2 S 4 2 S 3 4

A straight wire carrying a current of 12 A is bent into a semicircular arc of radius 2 cm as shown in figure i the magnitude of B in tesla at the centre of the arc is x 10 5 tesla value of x is Figure i

5 24 A uniform rod AB of mass Mis placed in contact with a second rod BC of mass m M 2 on a horizontal smooth table at right angles to each other as shown in figure 5 141 Find the initial velocity of BC and kinetic energy generated in it if an impulse I is imparted to A ns 21 3m 51 3m1 I A Figure 5 141 B C B

c A system has three energy levels 0 E 2E The energy level E is two fold degenerate and the other two are three fold degenerate Find the partition function Helmholtz free energy and heat capacity of the system 4

A man is walking under an inclined mirror at a constant velocity 10 m s along the x axis If the plane mirror is inclined at an angle 8 with the horizontal then what is the velocity of image y TO 0 10 m s

The driver of a car moving towards a rocket launching pad with a speed of 6 m s observed that the rocket is moving with speed of 10 m s The upward speed of the rocket as seen by the stationary observer is nearly a 4 m s 1 b 6 m s 1 d 11 m s 1 c 8 m s 1

11 What is the magnetic moment in A m of a rectangular loop having 120 tur carries 6 0 A if its dimensions are 4 0 cm x 8 0 cm A 0 23 B 2 30 C 23 D 230 2 Which one of the following is not an electromagnetic wave A ultraviolet B infrared C radio waves D sound waves E gamma rays

Two spheres of same material are havi surfaces blackened and placed in spa separately Their radii are R and 2R respectiv and the most dominating wavelengths in th spectrum are observed to be in the ratio 1 Choose incorrect statement 1 The ratio of their temperatures is 2 1 2 The ratio of their emissive powers is 4 3 The ratio of their rates of heat loss is 4 4 The ratio rates of cooling is 32 1

A particle of charge q mass m moves rectilinearly under the action of an electric field E a Bx Here x is distance from the point where it was at rest a are positive constants A Motion is simple harmonic a C Mean position of particle is at B B Amplitude of particle is a B D Maximum acceleration of particle is q m

The diagram below shows a cross sectional view of a cylindrical pipe of varying diameter A B If an ideal fluid is flowing through the pipe find the true statement s A Volume flow rate is same at A B B The pressure is lower at point B than at point A C The volume flow rate is greater at point A than at point B D The flow speed is greater at point B than at point A

Find the time period of oscillation of the mass m in the figure given above All the springs have springs constant k k k vvvvvvvvvvvv k3 v vo o o o o o o o o o k4 k5 oooooooooooo A 2 2 m k 2m k m

4 1 66 19 A polyatomic gas has 3 translational rotational degrees of freedom and 2 vibrational modes What is molar specific heat ratio for the gas NCERT Pg 334 1 1 50 2 1 30 3 1 40 4 1 20 CAMERA 20 A cylinder of capitu The absolute ter increased three tin speed of gas 5 If the pressure of by drawing out pump the mean the gas is 6 Equal volu2021 07 29 21

Water is boiling in a large vessel as shown in figure If another vessel containing water is dipped in the bigger vessel as shown Choose correct option for water in smaller vessel 1 will not boil 2 will boil below 100 C 3 will boil above 100 C 4 will boil at 100 C

88 Which of the following statements is false regarding the vectors a The magnitude of a vector is always a scalar b Each component of a vector is always a scalar c Two vectors having different magnitudes cannot have their resultant zero d Vectors obey triangle law of addition The be ver launching pad with a speed of 6 m s observed that the Jok is mozing sob or the options dobb C MUSPICANIMS 2 1 rocket as seen by the

system 3 3 a A system has three different energy levels E 0 E 1 38 x 1023 J and E3 4 14x 1023 J with degeneracy 2 5 and 4 respectively What is the probability that the system is in the E level at 100K

Which of the following quantities is the same for all ideal gases at the same temperature A the total translational kinetic energy of the molecules in 1 mole gas B the kinetic energy of 1 gm C the number of molecules in 1 mole D the number of molecules in 1 gm

A copper atom consists of copper nucleus surrounded by 29 electrons The atomic weight of copper is 63 5g mol Let us now take two pieces of copper each weighing 6 35g Let us consider on electron from one piece is transferred to another for every 1200 atoms in a piece Avogadro s number 6x 1023 mol the coulomb force between the two pieces after the transfer of electrons if they W 10 N Find the are 4cm apart is value of W 1 ATE

A non conducting hollow sphere of mass m and radius R having total charge q is rotating with constant angular velocity o about a vertical axis as shown in the figure The sphere is then gently placed on the horizontal surface having a magnetic field applied in the horizontal direction as shown If there is sufficient friction to prevent any slipping then the friction force acting on the sphere at qoRB t 0 is Find the value of n m RI I 4 B

A circular disc is to be made by using iron and aluminium so that it acquires maximum moment of inertia about its geometrical axis It is possible with Question Type Single Correct Type 1 2 3 4 Iron and aluminium layers in alternate order Aluminium at interior and iron surrounding it Iron at interior and aluminium surrounding it Either 1 or 3

18 A heavenly body is observed from two diametrically opposite points and B on the earth The angle subtended at the heavenly body is 2 9 x 10 4 rad Given the diameter of Earth to be about 1 28 x 10 4 km Compute the distance of the heavenly body from the earth O 2 267 x 10 11 m 4 413 x 10 7 m 4 413 x 10 10 km 4 413 x 10 10 m

4 35 A chain is held on a frictionless table with one fifth of its length hanging over the edge If the chain has a length and a mass m how much work is required to pull the hanging part back on the table Ans Mgl 50

A stone is thrown with a velocity u making an angle with the horizontal The horizontal distance covered by its fall to ground is maximum when the angle 0 is equal to a 0 b 30 c 45 2019 d 90

Pg 247 and both a vector force 253 ains ing 6 L parabolic trajectory A manometer reads the pressure of a gas in an enclosure as shown in figure The absolute and gauge pressure of the gas in cm of mercury in the enclosure is Gas 1 76 20 2 20 76 3 96 20 4 20 96 Mercury 20 cm Take atmospheric pressure 76 cm of Hg NCERT Pg 250 9 10 s law 3 Both gases and liquids incre 4 Both gases and liquids dec The onset of turbulence which of the following figure s determined by 1 Pascal s law No correct regarding the steady fiquid 2 Avogadro number 3 Stoke s law 4 Reynold s number 2 A plane is in level flight and ea has an area 20 m If the spe upper and lower surfaces are m s respectively then the mas density of air 1 kg m NCS 1 1500 kg 2 1700 3 1650 kg 4 1750 1 3 4

An inductor of inductance L a capacitor of capacitance C and a resistor of resistance R are connected in series to an ac source of potential difference V volts as shown in figure Potential difference across L C and R is 40 V 10 V and 40 V respectively The amplitude of current flowing through LCR series circuit is 10 2 A The impedance of the circuit is T 2 3 g V 15 2 0 n 40 50 4 2 02 40 V10 V 40 V

V V b nRT where P V R T and n represent the pressure volume universal gas constant absolute temperature and number of moles of a gas respectively a and b are constants the ratio b a will have the following dimensional formula A M L 7 B M L T 1 MI T 272 D MIT

A force of 30 N acts on a body at rest of mass 10 kg for 60 seconds If the distance travelled in first 20 s is x next 20 s is x2 and the last 20 s is x3 then X X2 X3 will be equal to A 1 1 1 B 1 3 5 c 1 4 9