Basic Physics Questions and Answers

Choose the incorrect statements DIf linear momentum of system is conserved then angular momentum of system must be also conserved If angular momentum conserved then angular velocity must be also conserved about the same axis DIf net torque about any axis is zero then force must also be zero If net force on a body is zero torque about an axis through COM may be non zero

2 A particle of mass m is placed on the axis of a ring of radius R and mass M at a point P as shown in figure Gravitational force on the particle due to ring will be JK 3 1 3GMm 8R 2 FGMm M R 3 R 2 m SP GMm 4R GMm F GR

Three equal negative charges q each form the vertices of an equilateral triangle A particle of mass m and a positive charge q2 is constrained to move along a line perpendicular to the plane of triangle and through its centre which is at a distance from each of the negative charges as shown in the figure The whole system is kept in gravity free space Find the time period of vibration of the particle for small displacement from equilibrium position 9 9 A 4neomr 239192 B 2 C 2T D 2T Teomr 39192 Solution A 4 eomr 9192 3 omr 49192 Let the charge q2 is moved a distance a perpendicular to the plane of the triangle a a charge q2 from one of the vertices of triangle R 2 Let the angle between a and R is 0 Net force perpendicular to plane of triangle is 3F cos 0 Here 3kq192 x Fuet 3F cos 0 R2 R here ve sign indicates that force is opposite to displacement r a T 2TA 9 3kq192x m x 72 3 59142 4 com3 4 Mr 39192 Distance of x ma 2 as for small a i e

A small block of mass m is moving on a horizontal table surface at initial speed vo It then moves smoothly onto a sloped wedge of mass M The wedge can also move on the table surface Assume that everything moves without friction Which of the following statement s is are correct m Vo COM of the system always moves rightward COM of the system moves upwards for some time Speed of M always increases during contact with m Speed of COM of the system is always constant M

A straight wire carrying a current of 12A is bent into a semicircular loop of radius 2 0 cm What will be magnetic field at the centre of the semicircular loop 1 B 1 9 x 104 TO 2 B 1 9 x 10 TO 3 B 1 9 x 10 TO 4 B 1 9 x 10 TO

An electron moves with a speed of 2 10 m s along the x direction in a magnetic field B 1 4j 3k tesla The magnitude of the force in newton experienced by the electron is the charge on electron 1 6 10 C 1 1 18 10 13 2 1 28 x 10 13 3 1 6 10 13 4 1 72 10 13

35 A charged particle moves insides a pipe which is my bent as shown in figure If R then force qB exerted by the pipe on charged particle at P is neglect gravity A toward center C zero B away from center D none of these 9 V B

43 A particle of mass 2 x 10 kg moves horizontally between two horizontal plates of a charged parallel plate capacitor between which there is an electric field of 200 NC acting upward And magnetic induction of 2 0 T is applied at right angles to the electric field in and direction normal to both E and v If g is 9 8 ms and the charge on the particle is 10 C then find the velocity of charge particle so that it continues to move horizontally A 2 ms B 20 ms C 0 2 ms D 100 ms

44 Current of 10 ampere and 2 ampere are passed through two parallel wires A and B respectively in opposite directions If the wire A is infinitely long and the length of the wire B is 2 m the force on the conductor B which is situated at 10 cm distances from A will be A 8 x 10 N B 4 x 105 N C 8m x 107 N D 4 x 107 N

occurs in green plants Study the diagrams and answer the questions that follow SUNLIGHT SUNLIGHT 1111 Green Plant A C D Mouse Dead Mouse Alive 1 Name the physiological process occurring in the green plant that has kept the mouse alive ii Explain the physiological process mentioned above 5 18 ICSE 20 the form of a chemical equation process in v Represent the above mentioned physiologic stated in for life on earth iv What is the significance of the process a 1 Why and the mouse an in

In Bohr atomic Model regarding transition of electron for hydrogen like atom following observation were noted Column 1 Initial energy level 1 N 3 11 N 5 III N 2 IV N 4 O II ii Q O IV iv R O IV iv S Column 2 Final energy level O III iii P 1 N 2 1 N 4 iii N 1 iv N 3 Column 3 Series Kinetic energy of electron will become 4 times of initial in the transition P Lyman series Q Brackett series R Paschen series S Balmer series

A ball of radius r moving with a speed v collides elastically with another identical stationary ball The impact parameter for the collision is b see figure 2 1 1 After collision ball 1 will come to rest and ball 2 will move with velocity making an b angle sin below the x axis 2r 2 After collision ball 1 will move with some b finite velocity making an angle cos 2r above x axis and ball 2 will move with some b 27 below 2r different making an angle sin the x axis 3 For perfectly elastic head on collision b 0 and for perfectly elastic oblique collision 0 b 2r 4 The balls must scatter at right angles

41 An electron accelerated through a potential difference V passes through a uniform transverse magnetic field and experiences a force F If the accelerating potential is increased to 2V the electron in the same magnetic field will experience a force A F B F 2 C 2 F D 2F

38 Four wires each of length 2 0 metre are bent into four loops P Q R and S then suspended in uniform magnetic field Same current is passed in each loop Which statement is correct A Couple on loop P will be highest B Couple on loop Q will be highest C Couple on loop R will be highest D Couple on loop S will be highest P R S

39 A beam of well collimated cathode rays traveling with a speed of 5 x 10 m s enters a region of mutually perpendicular electric and magnetic fields and emerges undeviated from this region If B 0 02 T the magnitude of electric field is A 10 V m B 2 5 x 10 Vm C 1 25 x 10 V m D 2 x 10 Vm

In the most general form of Bernoulli s 2 V P equation W z constant 2g each term represents a energy per unit mass energy per unit weight b c energy per unit volume of the above of

The equation is based on the following assumptions regarding the flow of fluid a steady frictionless incompressible and along a streamline b steady frictionless uniform and along a streamline steady incompressible uniform and along a streamline steady frictionless incompressible and uniform 1 c d z constant w 2g

32 A charged particle moving along ve x direction with a velocity v enters a region where there is a uniform magnetic field B from x 0 to x d The particle gets deflected at an angle 9 from its initial path The specific charge of the particle is where d qB A VCOS Bd B v tan Bd C Bd D v sine Bd

5 Two polarising sheets are placed with their plane parallel so that light intensity transmitted maximum Through what angle must either shee be turned so that light intensity drops to half th maximum value 1 30 3 60 2 45 4 90

Huygens principle of secondary wavelets may not be used to 1 Find the new position of a wavefront 2 Explain Snell s law 3 Explain laws of reflection

A block of mass 1kg is placed on a roughl horizontal surface connected by a light string passing over two smooth pulleys as shown Another block 1 kg is connected to the other end of the string The acceleration of the block on table is Coefficient of friction 0 2 P O 0 8 g 1kg 0 2 1kg

a circular path with constant speed then the angle between the direction of accelera and its position vector w r t centre of circle will be 1 Zero 3 T kash Educational 2 TC IN 5 2 4 2

5 When a thin transparent plate of thickness t and refractive index u is placed in the path of one of two interfering beam of light then path between two waves at the position central is 1 1 t 1 3 2 1 t 4 ut to mee Teleg ma

Choose the correct statements Whole mass of system is assumed to be concentrated at COM for calculation of moment of inertia O Whole mass of system is assumed to be concentrated at COM for calculation of gravitational potential energ O Whole mass of system is assumed to be concentrated at COM for calculation of linear momentum Whole mass of system is assumed to be concentrated at COM for calculation of kinetic energy

SolveLancer Test 3 moles of hydrogen gas undergoes a cyclic process Assuming the gas to be ideal the heat supplied to the gas is SolveLancer Test a 20510 J b 14510 J c 13510 J d 15530 I 4 atm 2 atm P A D 400 K B C 500 K T

The number of waves in a glass plate of thickness 4 cm is same as in 5 cm of vertical column of water of refractive index 4 3 then refractive index of glass will be Question Type Single Correct Type 1 2 3 5 3 5 4 16 14

A uniform rod of mass m 7kg and length 1 m is fixed from point A which is at a distance 1 4 from one end as shown in the figure The rod is free to rotate in a vertical plane The rod is released from horizontal position Find the reaction force in N at the hinge when kinetic energy of the rod is maximum 114 A

12 Each question is followed by two statements P and Q Mark your answer using the following instructions If LCM of two numbers is 90 then what are the numbers P One of the numbers is 18 Q HCF of the numbers is 3 A Question can be answered by using both the statements together but not by either of the statement alone B the question cannot be answered even by using both the statements together C If the question can be answered by using either of the statements alone D If the question can be answered by using one of the statements alone but not by using the other statement alone

26 Two particles A and B of masses mA and ma respectively and having the same charge are moving in a plane A uniform magnetic field exists perpendicular to this plane The speeds of the particles are VA and Va respectively and the trajectories are as shown in the figure Then A MAVA MBVB C m m and v V B MAVAMVB D m mg and v VB

A particle moves from point 2m 5m 7m to 4m 7m 11m under action of a force F 21 31 7k N find work done by this force 28 J 38 J O 82 J

92 A microscope has an objective of 5 mm focal length and eye piece of 30 mm focal length and the magnification is 250 Then the length of the microscope for normal adjustment will be 1 150 mm 2 50 mm 3 100 mm 4 75 mm 3 A telescope has an obiective Telegram

3 2n Vg cose 68 Two particles each of mass m are moving in horizontal circle with same angular speed If both string are of san length then the ratio of tension in string T 1 32 3 2 is m 2 3 4 level circular track with unif 1 3 m The direction of F the re tana dvidt F vir For uniform circular m Note sider

A long U tube contains mercury and oscillates with time period T 2 s When 80 g of water is poured in one arm time period becomes T2 3 s The mass of mercury in tube in grams is PARAR

please explain it through the diagram that if a third polari zer she is placed in between the A and B then if the angle between a and b is theta then how the angle between Ba nd C is also theta Unpolarized light of intensity I is incident on a system of two polarizes A followed by B The intensity of emergent light is I 2 If a third polarizer C is placed between A and B the intensity of emergent light is reduced to I 3 The angle between the polarizers A and C is 0 Then A B C D cos 0 cos 0 1 4 cos 8 1 4 1 2 3 2 2

A ceiling fan is rotating with a frequency of 3000 rpm If we switch off the supply it stops after 30 seconds with a constant angular acceleration then The initial angular velocity is 100 rad sec 10T rad s 3 The average angular velocity is 50 rad sec The average angular acceleration is Total number of revolution made by the celing fan will be 750

if G is universal gravitational constant then ratio of have dimension F is gravitational force aft Gardie gedia Audi 8 Fra O M L M L 2 ML T 2 O IM T 21 urafat

Water flows into a container of 1000 L at a rate of 180 3t gal min for an hour where t is measured in minutes Find the amount of water that flows into the pool during the first 20 minutes 1 4000 gal 2 2800 gal 3 4200 gal

10 Figure shows graph between and V for two conductors A A Gust 1 1 1 3 3 1 30 30 B V V 2 1 3 4 1 2 tional Services Limited Regd Office Aakash Tower 8 Pusa Road New Delhi 11000

com out Ctrl Minus Tactive muta vi glass An equiconvex lens of focal length 10 cm in air and R I 3 2 is put at a small opening on a tube of length 1m fully filled with liquid of R I 4 3 A concave mirror of radius of curvature 20 cm is cut into two halves M and M and placed at the end of the tube M and M are placed such that their principal axes AB and CD respectively are separated by 1 mm each from the principal axis of the lens A slit S placed in air illuminates the lens with light of frequency 7 5 x 10 4 Hz The light reflected from M and M forms interference pattern on the left end EF of the tube O is an opaque substance to cover the hole left by M and M Width of the fringes on EF is xx 10 um Find the value ofx E a 5m b 3m c 6m a A S 20cm A C O MIB Imm Imm D M

An elastic ball of mass m is suspended from a fixed point by an inextensible string A small particle of same mass m moving towards it at an angle of 37 with the vertical hits the ball directly with the velocity vo The coefficient of restitution is The impulse due to tension in the string due to collision is 2mz 17 Find x Refag 37 at an affal I e fat an Atga ter v 2 2mz 17 31

45 If water drops are falling at regular time intervals from ceiling of height H then position of drop from the ceiling is when nth drop falling from the ceiling and rth drop is in its way 1 3 n 1 n r n r 1 In H H 2 4 n r n 1 H n 1 H n r

A bar magnet of pole strength 2A m of 4 cm length placed in uniform field of 5T in such a way that its magnetic equator makes 60 angle with field direction then torque on magnet is Question Type Single Correct Type 1 0 2 N m 20 4 3 N m 3 3 4 N m 4 2 N m

An electron is in a state with spin wave function 312 1 2 in the S representation What is t probability of finding the z component of its spin along the 2 direction a 0 75 b 0 50 c 0 35 d 0 25

Aakash Institute 103 The focal length of a convex lens is 20 cm An object is placed at a distance 30 cm from its focal point The ratio of the size of the real image to the object is 1 2 3 2 20

16 From a disc of radius R a concentric circular portion of radius r is cut out so as to leave an annular disc of mass M The moment of inertia of this annular disc about the axis perpendicular to its plane and passing through its centre of gravity is MP PET 2001 a 1 2 M R r c 1 2 M R r 4 b 1 2 M R 2 d 1 2 M R p4

01 An object and a plane mirror are approaching each other with a speed of 2m sec and 1m sec respectively The velocity of image will be 2 2m sec 1 4m sec 3 3m sec 4 6m sec

Find the magnetic field at point O due to semi infinite wire shown in figure ly 1 2 3 4 2 ol 4 R 2 oI 4 R 45 Out of plane of paper Into the plane of paper 2 1 Hol 4 R 2 1 Hol 4 R X Out of plane of paper Into the plane of paper

15 A particle of mass m and charge Q is placed in an electric field E which varies with time t ass E E sinot It will undergo simple harmonic motion of amplitude A C QE2 2 mo QE Vmo 2 B D QEo 2 mo QEo mo

Consider the electrical power is produced by using the sample of Pu in the alpha decay and the mass of the sample of 239 Pu is 10 kg Assume the electrical device works with 60 of efficiency Calculate the power produced in this process a 200 W b 600 W c 55 W d 11 6 W

A long coaxial cable carries current I Current flows down the surface of the inner cylinder of radius a and back along the surface of outer cylinder of radius 2a as shown The self inductance per unit length of the coaxial cable is yg a augu hda wa ugu fh g 21 ER AU a kc udz 92 gmiza ata am taf xzur A642 2a dy da dg jfta mua ata Zi ad amefu da c uf c at za zcca a tic A B Holn2 4 2 ln2 Holn2