Physics Questions

A bar magnet is lying in equilibrium inside a uniform magnetic field B If W be the work done to rotate it through an angle 0 then the torque required to hold it in that position is A W cot B W tan C W cote D W tan 0 2 2

1 10 10 cm 2 10 20 cm 3 20 10 cm 4 20 20 cm A convex lens forms an image at a distance 10 cm when a parallel beam of light is incident on it Find the position s of a concave mirror of radius of curvature 5 cm such that the final image is formed at infinity 1 At a distance of 10 cm from the lens 2 At a distance of 15 cm from the lens 3 At a distance of 5 cm from the lens 4 Both 1 and 2

Q66 Referring to the figure below the effective resistance of the network is r ww 1 2r 2 4r 3 10r 4 5r 2 r www r r 92 From NCERT www

View In English Diagram shows symmetrically placed rectangular insulators with uniformly charged distributions of equal magnitude At th origin the net field Enet is aligned with the negative x axis aligned with the negative y axis aligned with the positive y axis aligned with the positive x axis YA X

An electron mass m with an initial velocity v v i v 0 is in an electric field E Ei Eo constant 0 It s de Broglie wavelength at time t is given by a 1 c 20 No eEot mvo 0 b 21 d t eEot mvo

In the arrangement shown in figure the mass of the wedge Mis 10 kg and the mass of the body mis 4 kg The coefficient of friction between wedge M and mass m is 0 5 There is no friction between wedge and horizontal surface Neglecting the masses of pulley and strings the acceleration of the wedge M in m s2 is Take g 10 m s M

A tuning fork of frequency 340 Hz is held vibrating at the open end of an empty measuring cylinder of length 100 cm Water is then poured in it slowly What is the minimum height of water in cylinder for which resonance will be obtained Velocity of sound in air 340 m s Neglect end correction A B C D 25 cm 75 cm 80 cm 50 cm

variation of mobility u of electrons with applied electric field E in a metallic conductor HA 1 2 3 HA E E E

iTutor All India Aakash Test Series for NEET 2021 3 Two conducting spheres of radii 2 cm and 4 cm have equal surface charge density The ratio of electric potential on their surfaces is 1 7 1 2 6 7 4 1 2 3 1 4

R A spherical part of radius 2 bigger solid sphere of radius R Assuming uniform mass distribution shift in the centre of mass will b 17 RIN RI 7 R 2 R 2 is removed from R 14 R

The drift velocity of the electrons in a current carrying metallic conductor is of the order of 1 10 m s 2 108 m s 3 10 m s 4 10 m s 1 2 3 4

270 Four wires of equal length and of resistances 10 ohms each are connected in the form of a square The equivalent resistance between two opposite corners of the square is 1 10 ohm 2 40 ohm 3 20 ohm 4 10 4 ohm

The activity of a radioactive sample is measured as 9750 counts per minute at t 0 and as 975 counts per minute at t 5 minutes The decay constant is approximately 1 0 230 per minute 2 0 461 per minute 3 0 691 per minute 4 0 922 per minuta

An AIR station is broadcasting the waves of wavelength 300 metres If the radiating power of the transmitter is 10 kW then the number of photons radiated per second is 1 1 5 1029 3 1 5 1033 2 1 5 1031 4 1 5 1035

Supe A block rests on an inclined plane making an angle of 30 with the horizontal The coefficient of static friction between block and the plane is 0 8 If the frictional force on the block is 10 N then mass of block in kg Take g 10 m s 2 2 5 4 1 5 1 2 0 3 4 0

Equivalent resistance between A and B will be ww 3023 A 352 302 352 1 1 2 ohm 2 18 ohm 3 6 ohm 4 3 6 ohm 30 352 352 2 ihtonio Co bination ww B 352 3 Rogietora I 4

The equivalent resistance of resistors connected in series is always 1 Equal to the mean of component resistors 2 Less than the lowest of component resistors 3 In between the lowest and the highest of component resistors 4 Equal to the sum of component resistors 1 2 3 Subtopic Combination of Resistors I 4

29 The length of each side of cubical vessel is If charge q is placed at one of the vertices of the cube as shown in the figure then flux passing through the shaded portion of cube is C 1 9 24 9 q 2 9 9 ak 33 34

11 A ladder of mass M and length L is supported in equilibrium against a smooth vertical wall and a rough horizontal surface If 0 be the angle of inclination of the rod with the horizontal then normal reaction of the wall on the ladder is 30 Tub 1 Mg 2 3 4 Mg 2 tane Mgcote 3 Mg 20058 elpoe 0 rough smooth 200

32 The network shown in the figure is a part of a complete circuit If at a certain instant the current i 1 A and potential at point A and B are equal then the value of A 1 400 A s 2 300 A s 3 800 A s 4 200 A s di dt is L 10 mH www R 20 6 volt B AC circ V V s power co 1 3 Volc 2 Volo 2 37 An AC Sc voltage c 1 May 3 Is ne

20 The resistance of the resistor shown below is De Violet Green Orange Gold 1 75 x 10 2 5 3 75 10 10 2 74 x 10 2 5 4 76 x 10 2 5

An insect crawls up a hemispherical surface very slowly The coefficient of friction between the insect and the surface is 1 3 If the line joining the center of the hemispherical surface to the insect makes an angle a with the vertical the maximum possible value of a is given by cot a n Find n

Diagram shows symmetrically placed rectangular insulators with uniformly charged distributions magnitude Enet is equal At the origin the net field YA of of X O aligned with the negative x axis O aligned with the negative y axis

25 Total uniform charge on a sphere of radius 2 cm 10 C The maximum electric field due to the spher is Nendation mited 1 2 25 N C 3 491 N C 2 225 MN C 4 600 mN C

2 The position of a particle moving along x axis given by x 2t 3t 5 m The acceleration of particle at the instant its velocity becomes zero is 1 12 m s 2 12 m s 3 6 m s 4 Zero

An atomic power nuclear reactor can deliver 300MW The energy released due to fission of each nucleus of uranium atom U238 is 170 MeV The number of uranium atoms fissioned per hour will be 1 30 x 10 5 3 10 x 102 2 4 1022 4 5 x 10 5

16 The current through the 2 2 resistor in the circuit shown below is 5 volt 1 3 A from a to b 2 3 A from b to a 3 2 A from b to a 4 1 A from b to a 10 volt 192 102 b 2 N

A projectile is thrown horizontally from top of a tower of height 20 m with a velocity 10 m sec It strikes the smooth ground whose co efficient of restitution 0 5 g 10 m s2 neglect friction The time elapsed in seconds after projection when it strikes the ground 1st time will be 4 sec The time elapsed in seconds after projection when it strikes the ground 1st time will be 2 sec The time elapsed in seconds after projection when it strikes the ground 2nd time will be 3 sec The time elapsed in seconds after projection when it strikes the ground 2nd time will be 4 sec

of a rent ual 36 If a current flows in an 2 AC circuit across which an AC potential of V Vosinot has been applied then the average power consumption P in the circuit will be 1 2 2 Volo Volo 2 Volo lo sin wot

39 The inductance of a closed packed coil of 400 turns is 8 mH A current of 5 mA is passed through it The magnetic flux per turn is Ho Permeability of free space 1 3 1 4T 1 3T Ho Wb Ho Wb 2 1 27 No Wb 2T 4 0 4 Wb

1 Mg equilibrium against a smooth vertical wall and a rough horizontal surface If 0 be the angle of inclination of the rod with the horizontal then normal reaction of the wall on the ladder is 2 3 4 Mg 2 tane Mgcot 0 3 Mg 0 rough smooth

Q3 If a resistance coil is made by joining in parallel two resistances each of 2012 An emf of 2V is applied across this coil for 100 seconds The heat produced in the coil is 1 20 J 2 10 J 3 40 J 4 80 J 1 2 3 4

A particle starts from rest and moves along x axis The acceleration a varies with its displacement x as a 2 x m s Find magnitude of acceleration of particle when its displacement along positive x axis is maximum O 1 m s O 2 m s O 4 m s O 3 m s

A particle of mass m is taken with a constant speed v along the elliptical orbit as shown in figure semi major axis length a and semi minor axis length b 0 b a 0 0 b A The centripetal acceleration of particle at 0 b is B The tangential acceleration of particle at 0 b is zero va C The centripetal acceleration of particle at a 0 is b D The tangential acceleration of particle at a 0 is b a 0

70 In the circuit shown below to have same pote points a and b a dielectric of constant K 2 should be completely filled in C 1 F a HH 1 C 4 F 11 1 C1 and C3 3 C2 and C4 b C 4 F C 4 F HH 2 C1 and C4 4 C2 and C3

13 0 The moment of inertia of a uniform semicircular wire of mass m and radius r about an axis passing through its centre of mass and perpendicular to its plane is 1 mr 2 3 mr 1 4 2 mr 4 mr 1 0 4

The work done required to put the four charges together at the corners of a square of side a as shown in the figure is 1 q 4 a 2 6 q 4 2 6 q 4 None of these q q 1 4 a 2 3 q

The circuit consists of a capacitor connected in parallel to a resistor R with a coil of inductance L in series with them The power source could be an AC or a constant voltage DC source When AC source is applied then XL Xc R L vooroo C R If a constant DC source of voltage Eo is applied across the input terminal with a switch then Question Type Multiple Correct Type 1 Just after the switch is closed the initial current through the voltage source will be zero 2 Just after the switch is closed the initial current through the voltage source So will be R 3 The current through the voltage source long time after the switch is closed will be zero

15 14 Two capacitors G and C C C are connected in series and joined to a battery as shown in the figure C The plot which shows correct variation in potential as one moves from left to right on the branch containing the capacitors is S r

Which of the following is always true for an ideal gas that goes through an isothermal process No work is done on or by the gas The internal energy of the gas does not change The entropy of the gas does not change There is no heat transfer into or out of the gas

An object starts from rest from point P and comes to rest at point Q on same straight line It moves the first part of the distance with an acceleration 1 m s and for the remaining with retardation 2 m s2 If time taken to complete the journey is 2 s then find the value of distance PQ O O O 7 43 3 E 6 m

When light of wavelength is incident on a metal surface stopping potential is found to be x When light of wavelength n is incident on the same metal surface stopping potential is found to be Find the threshold X n l wavelength of the metal 1 n 3 n 2 n 4 n

In a characteristic X ray spectra of some atom superimposed on continuous X ray spectra Relative intensity 1 P represents Ka line 2 Q represents KB line 3 Q and P represents Ka and KB lines respectively 4 Relative positions of Ka and KB depend on the particular atom

80 railway wagons all of same mass 5 x 10 kg are pulled by an engine with a forc of 4 x 105 N The tension in the coupling between 30th and 31st wagon from th engine is A 25 x 104 N 1 B 20 104 N D 40 104 N To one of its ends a mass of 3kg C 32 104 N X

D D A ring of thin wire with active resistance R and inductance L rotates with constant angular velocity in the external uniform magnetic field perpendicular to the rotation axis In this process the flux corregnetic induction of external field across the ring varies with time as 6 40 cos at Pick the A B C For ferromagnetic Earth has a magnetic field very much geographic south pole to geographic north pole sin ot Power developed in the circuit due to rotation is given by L R The mean mechanical power developed by external forces to maintain rotation is equal to 1 w R P 2 R w L The mean power developed in the circuit is equal to P el cos where tan 2 OL R and lo is peak current The mean mechanical power developed by external forces to maintain rotation is equal ER where lo is peak current

3 1 2 4 4 1 5 The dielectric strength of air is 5 x 10 V m The maximum charge that can be given to a solid sphere of radius 1 m is charge is distributed uniformly 1 10 mC 2 5 mC 4 9 mc 5 3 g 3 Which of the following configurations of electrostatic mC

3 4800 02 4 5800 52 3 4800 2 26 If current is passed through a spring then spring will 26 after fein 1 Expand 2 Compress 1 3 Remain unchanged 4 Data not sufficient 27 When a capacitor of capacitance C is charged by a battery of V volt then the ratio of energy stored in capacitor to the heat produced during charging is 1 1 1 2 1 2 3 2 L 4 1 10 28 Acylindrical metal wire of resistance 902 is stretched uniformly to tripled its length Its new resistance will be 1 27 Q 540 2 8102 4 144 2 9 L 9 l ga 27 Pe 10 28 1 venta 3 3rfaffer Cal a safer faren G 1 1 1 3 2 1 902 vfart est e wala wird er 200270 Visao

In a coil of self inductance 20 mH the current varies with time t as shown in the figure 1 A LO 5 t ms 50 The magnitude of change in flux the coil from time t 0 to t 50 ms is 1 Wb

A ring of insullating material is situated at one end of a semi infinite long line of charge If is charge per unit length for ring as well as line charge and R is radius of ring Plane of ring is perpendicular to line charge Finc tension in ring

Some cases regarding vertical circular motion each circular path is having radius R are shown in Column 1 Column 2 shows tension normal at point B While column 3 indicates Information regarding path and motion Column 1 11 III String 60 B u 2gR String String B 3gR Fixed i ii iii Column II Tension Normal at point B is zero Tension Normal at B is 2mg Tension Normal at 3mg point B is 2 P Q R Column Ill Path will be circular Motion will be complete vertical circular motion Motion will be oscillatory Motion will Save Next