Physics Questions

ball falls from height h After 1 second another ball falls freely from a point 20 m below the point from where the first ball falls Both of them reach the ground at the same time What is the value of h ig 10 m s

A transport plane travelling at a steady speed of 64 ms and an altitude of 68 m releases a parcel when it is directly above a point Q on level ground a What is the time of flight in s of the parcel b What is the horizontal distance in m from Q to the point of impact c What is the speed in ms of impact of the parcel

Innumerable physical phenomena happening around us can be understood A only with the help of a large number of complex physical laws B only by building mathematical models C using only a small number of basic laws D only by designing experiments

4 The maximum possible efficiency of a hea engine is 1 100 T 2 2 1 T 4 Dependent upon the temperature of source 7 and sink T and is equal to 1 7

A ring composed of three sections The cross sectional area is 0 001 m for each section The mean arc length are Ia 0 3m Ib 0 2m Ic 0 1m An air gap length of 0 1 mm is cut in the ring ur for sections a b c are 5000 1000 and 10000 respectively Flux in the air gap is 7 5 10 WB Find 1 MMF 2 Exciting current if the coil has 100 turns 3 Reluctance of the sections

In an experiment an object is heated The data from the experiment is shown The energy transferred to the object is 3 0 kJ The mass of the object is 2 0 kg The rise in temperature of the object is 10 C The specific heat capacity of the object is 150 J kg C What is the thermal capacity of the object A 30J C B 300J C C 3000 J C D 9000 JA

b A sample of Ge is doped to the extent of 10 4 donor atoms cm and 7x10 3 acceptor atoms cm At temperature of the sample the resistivity of pure intrinsic Ge is 60 cm If the applied voltage is 2 V cm find the total conduction current density Here mobility of electron is 3800 cm V sec Mobility of holes is 1800 cm V sec 4

Question 23 X In the circuit shown in figure Xc R 2 9 i the value of x M M 4 00 through source is R wwwwww C HH ooooo N M 0 00 the peak value current xVo 2R Find

amped Harmonic Motion 29 The quality factor of a sonometer wire is 4 000 The wire vibrates at a frequency of 300 Hz Find the time in which the amplitude decreases to half of its initial value 20 2 4000 4 24 s

the capacitors in Fig 4 72 are initially uncharged and are connected as in the diagram with switch S open The applied potential difference is Vah 360 V ab 3 00 F 6 00 F d H a S 6 00 F 3 00 uF Fig 4 72 b

16 A transverse wave is represented by equation y yo sin 32 74 ut k For what value of 2 is the particle veloc equal to two times the wave velocity a Yo b c TY 2 d 2 yo

A body of mass 30 kg stands on a weighing machine lying on the floor of a lift What will be the weight of the body when i lift moves upwards with an acceleration 2 2 ms 2 ii lift moves downward with an acceleration 2 2 ms and iii lift falls freely Given g 9 8 ms2

ST 3 4 12 12 21 A particle is executing S H M between x A The time taken to go from 0 to is T and to go from to A is T then 1 T T T 2 T T T 2T

Q8 A particle starts from rest at t 0 and starts moving on a circular path of radius m with 4 TC tangential acceleration 6 m s2 where t is in seconds Calculate acceleration of the particle when it completes one revolution in m s Options 12 167 1 12 1 97 12 16 1718 16 skippec

The value of the Plank constant we measure here h 6 4 0 2 x 10 34 J sec is in agreement with the standard measured value 6 62607004 10 4 J sec The large error here are due to effect of O the reverse photo currents O temperature variation O all of the above O the broad wavelength width of the filters

Define losses of transformer The efficiency of 400KVA singe phase transformer is 98 77 when delivering full load at 0 8 pf lagging and 99 13 at half full load at unity pf calculate 1 Iron loss 2 Copper loss

A positive point charge qo is placed t a point C inside the cavity in spherical conductor as shown in figure Find the electric potential at point P Given K 1 Kqo 2a 2Kq 1 41E0 P a 2 C 7th 2a 2 4 Kqo a L 3Kqo

Question 35 A Activity of a radioactive nuclei 100x sample is 6 023 1012 dps then mass of radioactive nucleii sample will be given 2 of X is 10 min B C 10 10 gm M M 4 00 6 10 10 gm 10 11gm N M 1 00 Correct Answer

Tom Screen pus It implies that the field at every point on a circle of radius r with the wire along the axis is same in magnitude In other words the magnetic field possesses what is called a cylindrical symmetry The field that normally can depend on three coordinates depends only on one r Whenever there is symmetry the solutions simplify

A particle is moving with speed v b x along positive x axis Calculate the speed of the particle at time t V T assume that the particle is at origin at t 0 1 b t 4 b t 2 2 Band 3 b t 4 b t 2

Three particles of masses 1 kg 2 kg and 3 kg are placed at three corners of a right angled triangle of sides 3 cm 4 cm and 5 cm as shown in the figure The centre of mass from 1 kg mass is y axis 3 cm 0 0 3 kg 4 cm 1 kg O 1 33 cm 1 5 cm 2 cm 1 cm 2 kg 1 14 cm 1 5 cm 1 7 cm 0 9 cm x axis

Question 18 M M 4 00 Three alternating voltage sources V 3 sin oot V 5sin ot volt and connected Q 3 volt N M 1 00 V 5sin ot across a resistance R as shown in the figure corresponds where and to 30 and 127 respectively Find the peak current in Amp through the resistor 7 352 volt

Waves from two different sources overlap near a particular point The amplitude and the frequency of the two waves are same the ratio of the intensity when the two waves arrive 90 out phase to that when they arrive in phase is 1 1 1 3 1 2 2 1 2 4 1 4

An ideal heat engine working between temperature T and T has efficiency n If both the temperature are raised by 50 K each then the new efficiency of heat engine will be Equal to n Less than n Greater than n Can t predict

7 Two identical springs have the same force constant 73 5 Nm The elongation produced in each spring in three cases shown in Figure 1 Figure 2 and Figure 3 are g 9 8 ms wwwwwww wwwwwwww 5 kg Figure 1 m 00000 5 kg Figure 2 4 m 1 3 5 kg Figure 3 1 3 22 TE SI y ph 1 3 23 Fo th m 1

Q7 The velocity of a particle varies with time as v 31 4 5t 3 m s Find the average velocity of the particle for a time interval between t 0 and a time when the speed of the particle becomes minimum Options 31 23 m s X 61 57 m s 41 3 m s 31 5m s

A non conducting ring of radius R and mass m having uniform charge distribution having a small cut of length b b R is released from rest with its plane parallel to uniform electric field of strength E as shown in the figure If the maximum angular then find the value of C Neglect gravity velocity of the ring is CqEb 22mR R E 90

Question 20 A A damped oscillator has a frequency that is 0 8 times its undamped frequency By what factor is the amplitude of the oscillator decreased during each oscillation B el 2x M M 4 00 1 5x N M 1 00 Correct Answer

An oil drop carries six electronic charge has mass of 1 6 x 10 12 g and falls with terminal velocity in air What magnitude of vertical electric field is required to make drop upward with same speed as it was for only moving downward 16 KN C 1 32 7 KN C 1 48 5 KN C 1 0 68 KN C 1

Energy band gap of silicon is 1 14 eV 19 f Maximum wavelength at which silicon will start showing conductivity is 1 10888 nm 3 108 88 nm Mo 2 1088 8 nm 4 10 888 nm 20 1 14 eV for fufce cal 1 10888 nm 3 108 88 nm 2 108 4 10 frica Mobility

agnetic field If shape of the coil is varied witho ut chang ing its perimeter and current through it torque act ing on it will be 1 same for any shape of coil 2 maximum for a square shape

01 A marble is bouncing down a stairs in a regular manner hitting each step at identical points and then rising the same height H above each step Height and 05 depth of a stair each are equal to h as shown in the figure Coefficient of restitution for each bounce is e READ LESS The height H attained by the marble after a bounce is A T H eh 1 e

carpet is laid on the floor having mass per unit length A External force required to move one end of the carpet with uniform velocity Vo as shown in figure is 77 O2AV2 O AV2 O XV2 2 11 2 V

3 CW In horizontal plane A current is flowing in electricity line towards north the direction of magnetic field at a point which is just 4 CW In vertical plane below the line 1 towards north K 2 towards south 4 towards west the direction of magnetic field of a point which 3 towards east

Five capacitors are connected as show n in the figure Initially all capacitors ar e uncharged and S is open When S is c losed then the potential difference bet ween points M and N is assume steady state to be achieved af ter S closes sir please solve it by Kirchoofs current I aw not by KCL 7v S 6 F 4 F N 2 F 4 F HE 1 2uF 31v

15 In the adjacent figure if the incline plane is smooth and the springs are identical then the period of oscilla of this body is 1 2n 3 2 M 2k M ksine 2 4 2 2M Msin 10

on both P and Q 20 A body Q is placed on a frictionless surface On the upper surface of Q which is rough another body P is placed and it is pulled in forward direction with 100 N force Both P and Q move together in forward direction without P slipping over Q Find the direction of frictional force on P and Q 100 N Q On P and Q in backward direction B On P and Q in forward direction C On P in backward direction and on Q in forward direction D On P in forward direction and on Q in backward

A small orifice of area a is at the bottom of a tube of cross sectional area 3a Water filled up to height H in it and orifice is opened Acceleration of surface of water when water level falls to height H is 3g 9

In the circuit shown X is joined to Y for a long time and then x is joined to Z The total heat produced in R is XH 1 2 3 4 LE 2R LE 2R22 LE 2R R2 LE R 2R R 00000 L E X Z www R

Q No 85 to 86 A crystal belongs to a face centered cubic lattice with four atoms in the unit cell The size of the crysta is 1 cm and its unit cell dimension is 1 nm is the scattering factor of the atom The number of atoms in the crystal is 4 a 2 10 1 c 2 x 1023 The structure factors for 010 and 200 reflections respectively are a 2f and zero b zero and 4f c 2f and 2f d zero and zero b 4 10 d 4 x 1024 2

A lift is going up The variation in the speed of the lift is as given in the graph What is the height to which the lift takes the Velocity ms 3 6 passengers a 36 m b 28 8 m c 36 0 m d Cannot be calculated from the above graph 2 G Time s 10

A particle travels in circle of radius 20 cm at a speed that uniformly increases It speed changes from 5 m s to 6 m s in 2 s The angular acceleration is 2 rad s 2 2 5 rad s 5 rad s 2 1 5 rad s 2

Q5 In the arrangement shown mass of pulley P is m and pulley Q is massless Both the pulleys are frictionless There is friction between m and ground whereas surface between 2m and inclined plane is smooth If the system is in equilibrium force applied by clamp on pulley P is Options mg 2 30 mg 3i 57 mg 31 57 2 3i 37 mg 31 33 m

a Obtain the equivalent circuit of a 200 400 V 50 Hz single phase transformer from the following test data O C test 200V 0 7A 70 W on L V side S C test 15V 10A 85W on H V side Calculate the secondary voltage when delivering 5kW at 0 8 pf lagging the primary voltage being 200V

Teacher please explain isn t 1kohm our output resistance And if we find Vc across 1kohm then will it not be the ans wer Why we minus 18 Vc Please explain my concept Im ery confused 15 A common emitter amplifier is shown in the figure If 200 and VBE 0 5 V then value of Ic and VCE respectively will be NCERT Pg 499 5 V 90 kn www B 1 10 mA 10 V 1 kn C E 18 V 2 10 mA 8 V

The block A in figure weighs 100 N The coefficient of static friction between the block and the table is 0 25 The weight of the block B is maximum for the system to be in equilibrium The value of T is T QUX T T A B imunin 45

A particle starts with an initial velocity of 2 5 m s along positive x axis How much distance will it cover in reaching velocity of 7 5 m s with uniform acceleration of 0 5 m s 20 m 30 m 40 m 50 m

5 An L C circuit contains a 20 mH inductor and a 50 F capacitor with an initial charge of 10 mC The resistance of the circuit is negligible Let the instant the circuit is closed be t 0 At what time is the energy stored completely magnetic a t 0 c t 3 14 ms b t 1 57 ms d t 6 28 ms

34 A sphere centered at the origin has radius 0 200 m A 500 C point charge is on the x ax x 0 300 m The net flux through the sphere is 360 N m C What is the total charge inside sphere

Calculate the hinge force when the rod of mass M becomes vertical Initial situation is shown in figure and string is then cut hinge is frictionless wym O Fx 0 Fy y Mg O Fx Mg Fy Mg O Fx Mg Fy Mg O Fx 0 Fy Mg L 8