Basic Physics Questions and Answers

Which of the following statements is not true A The coefficient of friction between two surfaces increases as the surface in contact are made rough T B The force of friction acts in a direction opposite to the applied force may be C Rolling friction is greater than sliding friction f D The coefficient of friction between d and wood is less than 1

20 The following circuit consist of a 5uF capacitor havin charge 50 C as shown The switch is closed a t 0 The value of current in 2 MQ resistor a t 0 is 1 1 A C 5 F HF q 50 C 2MQ S 2 2 A

A short bar magnet placed with its axis at with an external field of 600 G experienc torque of 0 024 N m Magnetic moment of magnet is NCERT Pg 1 0 4 A m 3 0 6 A m 2 0 8 A m 4 0 5 A m

A smooth wedge is kept in a chamber Chamber is suspended close to earth surface A block B is kept on top of wedge It takes time T to slip over length of wedge If block is kept on top of wedge suddenly string breaks then at this time block 1 will take more time than T to slip over wedge 2 will take less than T to slip over wedge 3 will remain on top of wedge 4 will fall away from wedge

A 50 kg mass is on an inclined plane at one end of a massless string passing through a smooth pulley of inclined plane and at other end of the string a 40 kg mass is suspended as shown in fig distance travelled by 50 kg mass in 4 sec will be angle of inclination of plane is 30 1 13 04 m 3 1 304 m 2 1 63 m 4 16 3 m 40g T mgcos mg mgsinE

On a rod of length L mass m how much tension will be at a distance y from F when two dissimilar forces F F F F are applied on the rod M 1 F 1 2 F2 2 2 F F M F y TT A F

1 I 2 11 3 III 4 In both i and III 14 The input signal given to a CE amplifier having voltage gain 100 V 20 mV cos 101 The correspond ing output signal will be NCERT P 491 1 2 V cos 10 2 2 V cos 10t 3 2 V cos 7 25 3 4 2000 V cos 101 SV 5 A common emitter amplifier is shown in the figure If 200 and VBE 0 5 V then value of le and Yes respectively will be 90 k 1 10 mA 10 V 2 10 mA 8 V 3 5 mA 8 V 4 10 mA 18 V 16 Which of the following relations is are correct Symbols have their usual meaning INCERT Pg 499 1 A B R edi JEE Foundation B 2 Ap R R 4 All of these 1 a 17 A transistor with CE configuration can be realized as INCERT Pg 502 1 NOT gate 2 AND gate 3 OR gate 4 NOR gate 18 A p n photodiode is fabricated from a semiconductor with band gap of 2 0 eV The maximum wavelength of a incident radiation that can be detected is INCERT Pg 487 1 7200 A 2 6200 A

1 Two bodies A B of mass m m are connected by a string as shown in fig If they are accelerated upwards then ratio of tension T T 2 1 m m mg 3 MA MB MA MB 2 m m mA MA MB MA MB 4 AMA AMB

Which of the following is are correct C A Speed of sound in air is the same for all wavelengths B If pressure of a gas is increased keeping the temperature constant the speed of sound wa the gas increases C In a travelling sinusoidal sound wave the phase difference between displacement wave pressure wave is TC 2 D In case of transverse waves both momentum and energy may transfer

d 0 75 m A thin uniform rod of length I and mass m is swinging freely about a horizontal axis passing through its end Its maximum angular speed is w Its centre of mass rises to a maximum height of AIEEE 2009 a c 11 w 3 g 11 w 2 g b d 1 lo 6 g 11 w 6 g

pard Competitive Exams 5 A satellite in force free space sweeps stationary interplanetary dust at a rate of dM dt av where M is mass and v is the speed of satellite and a is a constant The tangential acceleration of satellite is 1 2M 2ay 2 av gy

3 A point charge Q is located on the axis of a disc of radius R at a distance b from the plane of the disc figure Show that if one fourth of the electric flux from the 36 charge passes through the disc then R SHARE F F

temperature us temperature nted by graph aph is CERT Pg 104 among the following statements is NCERT Pg 104 correct 1 In metal number density is a independent of temperature 2 With increase in temperature relaxation time in metal decreases 3 For semiconductors and insulators number density increases with increase in temperature 4 All the above

4 6 V 12 An n p n transistor is configured in C configuration The input resistance is 2 ks and load is 10 k If 0 99 then voltag gain will be INCERT Pg 497 1 495 2 990 3 1000 4 500

Find the volume of a frustum of a pyramid with square base of side 16 square top of side 11 and heig Volume

While making up his schedule for spring semester Tom complains that he doesn t have very many choices of schedule because of the general education requirements he has to meet His advisor tells Tom that he has to take one course from each of English 4 choices History 2 choices Math Stats 6 choices Computer Science 4 choices and general Science 8 choices Does Tom have a legitimate gripe a If every possible course is available at the time he s registering how many possible schedules can he choose from disregarding when the classes meet Tom can choose from possible schedules b In an unprecedented effort to make the general education requirements more accessible the dean of Tom s college decides to triple the number of acceptable courses in each of those five areas What effect does this have on the number of possible schedules Tom can choose from are tripled The number of possible schedules is increased by a factor of possible schedules when the number of acceptable courses

z provide detailed solution to this question 4 A smooth right angled rigid triangular frame ABC made of a thin rod is fixed in a vertical plane A small bead starting from rest from corner A takes equal time t to slide down the arms AB and AC If BC 1 then A 1 t 3 t B 5 2g 21 a 16 2 t 4 t 81 5g 61 5g C

a Hull gave formulae for the cut off voltage and the cut off magnetic flux density for a magnetron Using these Hull expressions calculate the beam voltage VO if the inner radius of the magnetron is 0 05m outer radius is 0 15m and the magnetic flux density is BO 2mWb 10 Marks b Calculate the frequency for a cylindrical magnetron having the magnetic flux density of BO 150 T

80 Electric Charges and Fields 10 The incorrect statement among the following statements is NCERT Pg 25 1 Electric field lines can never cross each other 2 Electrostatic field lines do not form any closed loop 3 In charge free region electric field lines can be taken to be continuous curve 4 Field lines around a system of two positive charges is straight and parallel lines pictorially 11 A dipole consist of two charges q and q separated by a distance 2a The electric field of this dipole at distance r from centre of dipole at a point A on axis is NCERT Pg 28 2p 1 2 4 8 3 2p 4 Z P 4 12 Electric field of 4 1m 3m components 1 E 100 x2 E E 0 Calculate net electric flux though the cube placed in electric field at shown position 2pr 4x r a 12 3 3 m 3 m x axis are NCERT Pg 35 1 900 Nm C 2 1800 Nm C 1 3 600 Nm C 1 4 3600 Nm C 1 13 An infinite long straight wire has linear charge density 4 x 105 C m The electric force experienced by a proton at perpendicular distance of 10 mm from axis of wire is NCERT Pg 37 2 1 68 x 10 N 1 1 25 10 N 4 1 15 x 10 N 3 2 8 x 10 N 14 Coulomb s law of electrostatic for the force between two point charges most closely resembles NCERT Pg 12 1 Law of conservation of charges 2 Law of conservation of energy 3 Newton s second law of motion 4 Newton s law of gravitation 15 A point charge q of mass m is placed in front of a uniformly charged infinite sheet and released The surface charge density of sheet is a C m2 The kinetic energy of charge after t second is NCERT Pg 39 1 99 3 4 m 9 0 1 83m 3 2 4 9 0 1 com 9 0 1 43m 17 16 An electric dipole consists of two equal and opposite charges 0 02 C separated by 2 mm The dipole is placed is uniform 18 NCERT Maps electric field of 107 N C 1 Maximum torque exerted by field on dipole is 2 4 x 10 Nm 1 2 10 Nm 3 8 x 10 Nm 4 2 x 10 6 Nm A thin spherical shell is given a charge q 4 C uniformly distributed over its surface Consider a point P outside the shell at distance of 2 m from surface If the radius of shell is 1 m what is electric field at point P INCERT Pg 39 1 4 kN C 1 3 9 kN C 1 2 2 kN C 1 4 36 kN C 1 Figure shows track of three positive charged particles through uniform electric field E All charges are equal in value Which charge particle has more initial kinetic energy on entering horizontally between the plate INCERT Pg 47 undation INCERT Pg 31 20 3 1 Particle 1 2 Particle 2 Plate Plate 3 Particle 3 4 Both 1 and 2 have equal initial KE Office Aakash Tower 8 Pusa Road New Delhi 110005 Ph 011 47623456

4 Extension in spring is A metallic sphere is suspended on stationary wall with the help of a spring Forces as shown in the fig are acting on the sphere Which statement statements in following is true a N T W 0 c T N W 1 a b c 3 a b d b T N W d N W tane 2 b c d 4 a b c d z T VW F

6 Two cells of e m f E and E are joined in series and the balancing length of the potentiometer wire is 625 cm If the terminals of E are reversed the balancing length obtained is 125 cm Given E E the ratio E E will be 1 2 3 2 5 1 3 3 2 4 1 5 5

A resistor is marked with rings coloured as and gold The INCERT Pg 103 brown black green resistance in ohm is 1 3 x 106 5 2 X 2 1 10 105 5 2 X 3 106 5 4 8 5 10 5 2

3 300 N 1000 N A B are two particles of mass m each are kept stationary as shown in fig by applying a horizontal force F mg on B then a tan 2 tan c T 2 T 5 1 a b 3 c d b 2T 5T d none of these 2 b c 4 a c T B F mg T

Estimate the average drift speed of conduction electrons in a conductor of cross sectional area 107 m carrying current of 1 5 A The number density of conduction electrons is 8 5 x 1028 m 3 NCERT Pg 99 1 2 2 mm s 1 2 1 1 mm s 1 3 3 3 mm s 4 01 mm s 1

92 Aakash Educational Services Limited Regd Office Aakash Tower 8 Pusa Road New Delhi 110005 Ph 011 47623456 Current Electricity nichrome is 1 7 x 10 of nichrome now is C The temperature NCERT Pg 105 8 V 202 NCERT Maps

A person is standing on a floor of lift releases a coin Coin reaches on floor in time t if lift is stationary and coin reaches on floor in time t if lift is moving with uniform velocity 1 t t 2 t t 3 t t 4 t t or t t depends on lift on moving downwards or upwards

Choose the incorrect option for Bohr s model of hydrogen atom The radius of nth orbit is proportional to n The angular momentum of electron in an orbit is h 2 an integer multiple of The magnitude of potential energy of an electron in any orbit is greater than its kinetic energy Total energy of an electron in nth orbit is proportional to n

In the arrangement shown in fig friction between block table is negligible If F is pulling force and m m are known masses then tension in string will be 1 m F m m 2 2m F m m 3 2m F 4m m 4 none of these m m Of

Linear momentum of P of a body performing one dimensional motion is changing according to P at bt where a and b are positive constants then net force acting on the body is proportional to 1 1 3 t 2 a constant 4 1 t of morces M and m respectively M m They are holding

4 all of the above Two objects A and B each of mass m are connected by a light inextensible string They are restricted to move on a frictionless ring of radius R in a vertical plane as shown in fig The objects are released from rest at the position shown Then the tension in the cord just after release is 1 zero 3 2 mg 2 mg 4 mg 2 BO045

Force are acting on a body according to fig If body is moving horizontally at a300N M constant speed of 5 m s then value of P and S respectively will be 1 ON ON 2 300 N 200 N 3 300 N 1000 N 4 2000 N 300 N S S 2000N P fig by applying a horizontal

X Z Y Y Z X listen 3D geometry positive z axis may be converted negative Z axis but however when positive Z axis is replace negative Z axis it s always upward direction and upward means anticlockwise obviously but

The diameter of a plano convex lens is 5 cm and thickness at the centre is 5 mm If the refractive index of the material of the lens is 1 5 the focal length of the lens is approximately 1 13 cm 2 15 cm 3 20 cm 4 6 35 cm 1 2 3 4

3 3 2v right If masses are released from the position shown in fig then speed of mass m just before to collide on floor will be 1 2m gd m m 3 2 m m gd m 2 2 2 m m gd m m 4 none of these m m

6 A metal cylinder of radius 2 0 mm is concentric with another metal cylinder of radius 5 0 mm If the space between the cylinders is filled with air and the length of the cylinders is 50 cm what is the capacitance of this arrangement k 1 4c0 8 99 x 10 9 N m2 C2 OA 33 pF OB 60 pF OC 22 pF OD 30 pF O E 11 pF 1 point

The pressure of a medium is changed from 1 01 x 10 Pa to 1 165 x 105 Pa and change in volume is 10 keeping temperature constant The bulk modulus of the medium is 1 204 8 x 105 Pa 2 102 4 x 10 Pa 3 51 2 x 10 Pa 4 1 55 x 10 Pa DEOWORO BALTARGETENGSMODULE

A potential difference of 5 V is applied across a conductor of length 10 cm If drift velocity o electrons is 2 5 x 10 m s then electron mobility will be 1 5 10 4 m V 1 s 1 3 5 10 m V 1 s 1 4 Zero 2 5 x 10 6 m V 1 S 1

The circuit diagram shown here corresponds to the logic gate Vcc A OR NOR AND R Q24 B Vo Y

A rod has moment of inertia perpendicular bisector If the temperature of the rod is slightly increased by At then I will increase by 1 a At 3 3 a At 2 21 a st 4 Zero

6 A sample of 100 g water is slowly heated from 27 C to 87 C What is the change in the entropy of the water Specific heat capacity of water 4200 J kg K a 420 ln 1 2 JK c 120 ln 1 5 JK b 220 ln 1 4 JK d 320 ln 1 2 JK 420

A power transistor is specified to have a maximum junction temperature Ti max of UN 130 C When operated at this maximum temperature with a heat sink the case temperature Te is found to be 90 C The case is attached to the heat sink with a bond having a thermal resistance Ocs 0 5 C W and the thermal resistance of the heat sink 0SA 0 1 C W If the ambient temperature TA is 30 C what is the power being dissipated in the device What is the thermal resistance 0 c of the device from junction to the case

A copper r d of 88 cm and an aluminium rod of unknown length have their increase in length independent of increase in temperature The length of aluminium rod is 1 7 10 5 K 1 and A 2 2 10 5 K 1 NEET 2019 1 6 8 cm 3 88 cm 2 113 9 cm 4 68 cm

5 Two charges 6 nC and 4 nC are located 15 cm apart At what point on line joining two charges is electric potential zero NCERT Pg 58 1 6 cm from 6 nC charge 2 45 cm from 6 nC charge 3 38 cm from 6 nC charge 4 9 cm from 4 nC charge ti 16cm

1 A dipole consist of two charges q and separated by a distance 2a The electric field of this dipole at distance r from centre a dipole at a point A on axis is NCERT Pg 28 2p 1 2 3 4 r a 3 2p 4 P 4 or 4 2pr 4 o r a

6 Consider charges q q and q placed at vertices of an equilateral triangle as shown in figure Calculate force on q charge due to other NGERT Pg 171 3 9 200 29 T 9 4 4R 3q 4 2 cal IITTEE Foun

A point charge Q 4 x 107C is placed a point in free space How much work required to bring a charge 2 nC from infin to a point 9 cm from charge Q NCERT Pg 5 dicaron 1 3 104 J 2 8 x 10 5 J 3 2 x 10 5 J 4 5 x 10 5 J

2 The comparative graph of potential and electric field due to a point charge at a distance r from it is best shown by graph NCERT Pg 55 com 1 V E or 2 V E E V

c Choose the correct option 1 Which of the following is an effect of force a Starts motion c Stops motion 2 Which of the following is not a unit of force a gram force b dyne 3 Kneading dough shows which effect of force a change in speed c change in shape and size 4 Which of the following is not an effect of friction a To produce heat c To cause wear and tear of the surfaces 5 Which of the following is not a type of friction a Rolling friction b Static friction 6 Friction can be reduced by a using ball bearings b polishing b Changes the direction of motion d All of them c joule b change in direction d change in mass d newton b To increase the speed of the body d To oppose the motion of the body c Slowing friction d Sliding friction c streamlining d all of them

4 Find the expression for the equivalent capacitance when two capacitors having respective capacitances Cl and C2 are connected in parallel 3 5 Find the expression for the capacitance of a parallel plate capacitor having plate separation d when the space between the plates is filled by a dielectric having thickness 5

The wedge shown in the figure can slide without friction on a horizontal table top The mass of the wedge is M and its angle of elevation a 30 A body of mass m slides down without friction along the wedge the path of the body makes an angle of 60 with the ground Find the ratio of the masses m M A 1 B 2 C 3 D 4 m