Basic Physics Questions and Answers

A charge q is placed inside an uncharged hollow metallic shell of radius R Prove that the charge induced at the outer surface is uniformly distributed

A small conducting loop of radius r resistance R is pulled with velocity v perpendicular to long straight current carrying conductor carrying a current If the power dissipated P in the loop is constant find the variation of the velocity of the loop with the displacement x R X m given x r

Four arms of wheat stone bridge have the AB 60 2 following resistances BC 100 CD 60 DA 12 Q A galvanometer of 15 2 is connected across BD Calculate the value of additional resistance connected across CD to balance NCERT Pg 119 the bridge A 1 122 10 60 Q 12 Q B 100 Q G 15 Q D 60 Q 2 15 Q C

A person wearing glasses sees two images of a flower that is 5 0 m behind him One of these images appears 5 0 m in front of him and the other 0 714 m in front of him When he turns around and looks directly at the flower still wearing the glasses the flower appears 2 5 m in front of him Find refractive index of material of the glasses

5 47 An inductance of 2 0 H a capacitance of 18 F and a resistance of 10 ks are connected to an AC source of 20 V with adjustable frequency a What frequency should be chosen to maximise the current RMS in the circuit b What is the value of this maximum current RMS Ans a 250 3 Hz b 2mA

5 49 A stiff wire bent into a semicircle of radius R is rotated at a frequency f in a uniform magnetic field B Calculate the amplitude and frequency of the induced voltage If this circuit has negligible resistance and the internal resistance of the ammeter is 100092 calculate the amplitude of induced current

uctance 40 5 39 A vertical copper disc of diameter 20cm makes 10 uF revolutions per second about a horizontal axis passing through it centre A uniform magnetic field 10 2 weber m acts perpendicular to the plane of the disc Calculate the potential difference between its centre and rim Ans 3 14 10 V TC ulate

8 In a refrigeration system the refrigerant absorbs 21 390 J of energy from the system while expanding against a 0 278 atmosphere pressure from a volume of 0 0423 liters to a volume of 1 876 liters What is the energy change of this system A 1 73 kJ B 22 6 kJ D 20 2 kJ C 20 2 kJ

27 small mercury droplets each of radius R and charge q are combined to form a big drop The ratio between the potentials of bigger drop to smaller drop is 4 6 9

9 A potentiometer with driver battery of emf 2 V is used for determination of internal resistance of 1 5 V cell The balance point of the cell in open circuit is 225 cm When a resistance of 7 0 is used in external circuit across of the cell the balance point shifts to 210 cm length of potentiometer wire The internal resistance of the cell is NCERT Pg 131 1 12 2 0 5

4 22 A magnetising field of 1600 Am produces a magnetic flux of 2 4 x 10 5Wb in an iron bar of cross sectional area 0 2cm Calculate permeability and susceptibility of the bar Ans 7 5 x 10 4 N A 596

6 A conical vessel having base area 4 x 103 m and height 40 cm is filled with a liquid of density 0 9 gram cm What is the force acting on the base of the vessel due to the liquid column Use g 10 m s

In the figure shown below is a meter bridge set up with null deflection in the galvanometer The value of unknown resistance R is www 55 2 20 cm O 13 750 O 2200 O 1100 O 1650 ww R

If on the concentric hollow spheres of radii r and 4 R r the charge Q is distributed such that their surface densities are same then the potential at their common centre is 1 Q R r 4 R r 3 Zero 2 QR R r Q R r 4760 4 R r

An object A moving with a speed 0 65c relative to earth and another object B moving with a speed 0 75c relative to the object A Calculate the speed of the object B relative to the earth if these objects travelling in same direction a 1 00c b 0 20c c 0 94c d 0 10c

5 3 A metal disc of radius 25cm rotates at a constant angular velocity 130rad s about its central axis Find the potential difference between the centre and the rim of the disc if a The external magnetic field is absent b The external uniform magnetic field of induction 5mT exist which is directed perpendicular to the disc Ans a 3nV b 20mV

5 Two isolated conducting spheres of radii 10 cm and 20 cm have charges QA and QB respectively What is the final charge on the first sphere if the spheres are brought in contact and separated subsequently A 1 Q QB 3 B QA QB 1 2 Q Q D remains unchanged C QB

Find the initial current through the inductor and the current through it after a long time Switch is closed at t 0 A 2A 2A 10V 202 www B 10 11 A 0 A 3 Q www t 0 652 C 2A 0A lllllll 2H D 0A 2A

dm B dm dm E D dm P For the truss shown in the figure d 3 6 m and p 42 kN The Horizontal reaction at B KN The Vertical Reaction at B The Horizontal Reaction at C The Vertical Reaction at C Moment reaction at B Moment reaction at C The force in member BC The force in member BE The force in member EF KN KN kN m kN m kN kN KN KN ANSWER PLEAS Please note that in your answer if there are any members in compression suffix your answer with a negative s All these blanks are to be filled with numerical values only Do not fill them with charact

d None of these A varying magnetic flux linking a coil is given by xt If at a time t 3s the emf induced is 9V then value of x is a 0 66 Wb s c 0 66 Wb s b 2 5 Wb s d 1 5 Wb s2 15 Two ic withou increa a R b is 18

If a charged conducting shell has potential V at its centre What is electric potential at a point 30 cm from its surface radius of shell is 10 cm 3V 2V 4

Two charges 8 C and 6 C are held at certain distance apart in air attract each other with a force of 12 N A charge 4 C is added to each The electrostatic force between new charges held at same separation in a medium of dielectric constant 2 would be ON 12 N 3 N

A steel scale calibrated at 25 C has been employed to measure the length of a copper pipe at 25 C However the reading has been taken at 65 C If thermal coefficient of linear expansion of steel and copper are 3 x 10 5 per C and 2 10 5 per C respectively then percentage error in reading taken is 1 0 01 3 0 04 2 0 02 4 0 05

16 In a meter bridge experiment the balance point J is at a distance of 40cm from the end A given the resistance Y in the right gap is 1202 The bridge wire has a resistance of 20 10cm and is of length 100cm a Determine the resistance X in the left gap b if the meter bridge has 24V cell with internal resistance 2 2 driving current through it then draw the equivalent Wheatstone network

Hi teacher I m Harsh Vadher Teacher I differentciate but I did partially with Vx Vy and g ot X Y dependence and Z 2 m and so I got equations for X Y and got X Y 1 2 but distance is 3m The given answer in magnet is 3m Is my answer wrong Velocity of a particle moving in space is given by V yi xj 2k At initial moment t 0 the particle is at 2 0 0 Find the distance travelled in m by the particle in 1 s All quantities are in Sl units Consider following arrangement of three blocks A B and C Mass of the each block is 1 kg The coefficient

A plane infinitely large sheet carrying current j per unit width is as shown in the figure An infinitely long solenoid axis is parallel to the current in the sheet If the current in the solenoid is i Magnetic field in the interior of solenoid is zero then the number of turns per unit length is elle

A large number of 1 F capacitors are available which can withstand a potential difference of 250 V A technician requires a capacitance of 1 F in a circuit across 1000 V the minimum number of capacitors required will be INCERT Pa 891

The average energy of an electron in a specific metal at 0 K is 2 9 eV Calculate the valu of the Fermi energy in a specific metal A 5 51 eV B 2 44 eV C 4 83 eV D 2 83 eV

The divergence of the vector potential A is HQ 4 r here Q is a constant with dimensions Calculate the scalar potential 7 t that makes A and Lorentz gauge invariant a b c d O tatoto 4

9 A spherical capacitor consists of two concentric spherical conductors held in position by filling insulating material of dielectric constant 6 The inner sphere has radius of 10 cm and outer has 40 cm The capacitance of spherical capacitor is 1 100 pF 3 88 8 pF NCERT Pg 91 2 108 pF 4 73 3 pF

Q 1 A particle is travelling on a curved path In an interval At its speed changed from v to 2v However the change in magnitude of its velocity was found to be AV 5 v What can you say about the direction of velocity at the beginning and at the end of the interval At

Current Attempt in Progress 8 61 36j m s and Two 7 6 kg bodies A and B collide The velocities before the collision are A VB 8 01 2 2 m s After the collision 7 5 91 12 m s What are a the x component and b the y component of the final velocity of B c What is the change in the total kinetic energy including sign a Number THE Units Units

A particle approaches from very large distance towards concave mirror along the principal axis By the time the particle reaches the mirror the distance between the particle and its image 1 first decreases then increases 2 first increases then decreases 3 first increases then decreases and then again increases 4 first decreases then increases and then again decreases

In a photoelectric effect experiment if f is the frequency of radiations incident on the metal surface and I is the intensity of the incident radiations then choose the correct statement s A If f is increased keeping I and work function constant then maximum kinetic energy of photoelectron increases B If distance between cathode and anode is increased stopping potential increases C If I is increased keeping f and work function constant then stopping potential remains same and saturation current increases D Work function is decreased keeping f and I constant then stopping potential increases Select correct alternative 1 A B C 2 B C D 3 A C D

Graph shows stopping potential V 1 wavelength for for three metals then 3 1 2 1 Planck s constant for metal 1 is gre 2 Work function for metal 3 is greate 3 Threshold frequency for metal 1 is greate 4 Threshold wavelength is maximum for m

A neutral particle is initially at rest in a uniform magnetic field B as shown in the diagram The particle then spontaneously decays into two fragments one with a positive charge q and mass 3m and the other with a negative charge q and mass m Neglecting the interaction between the two charged particles and assuming that the speeds are much less than speed of light determine the time in us after the decay at which the two fragments first meet use the following data q 1 C B 2 T m 10 5 kg Both the charges have initial velocities in x y plane X PER X position of a neutraly particle before decay X X X X X X X X X X X X X

0 A proton of mass 1 a m u collides with a Carbon 12 nucleus mass 12 a m u at rest Assum ing that the collision is perfectly elastic and that the Newton s laws of motion hold what fraction of the proton s kinetic energy is transferred to the Carbon nucleus B C 144 169 48 169 25 169

16 When a thin transparent plate of refractive index 1 5 is introduced in one of the interfearing becomes 20 fringes shift If it is replaced by another thin plate of half the thickness and of R I 1 7 the number of fringes that undergo displacement is FUTE SERIES for Sri Chaitanya Sr ICON Students 141

A body is rolling without slipping on a horizontal floor The translation kinetic energy is 3rd of the total kinetic energy Identify the body A Hollow Cylinder B Hollow Sphere c Solid Sphere

3 A sphere of radius R carries a positive charge density p that increases linearly with radial distance r from the centre px r The radial dependence of the magnitude of electric field inside the sphere is given by A Exr B Ex r C Exr D Exr 2

nce Two conductors are separated by dis of 1 cm in air The dielectric strength of air is about 3 106 Vm 1 What maximum safe potential difference can be applied across conductors NCERT Pg 78 1 3 x 104 V 3 3 106 V 2 6 x 104 V 4 1 5 104 V

rings of spring constant K ed to block of mass m and s shown in figure a The on was observed to be T ical spring is attached as then new period will be INCERT Pg 345 a k voor Imm 19 A particle executes SHM has potential energy which changes with position If potential energy at equilibrium position is assumed to be zero then potential energy versus position graph is best represented by NCERT Pg 347 1 A 0 2 A 0 A A 20 The graph of a particle executing SHM is shown for two particles A and B The ratio of maximum accelerations of A to B is NCERT Pg 341 Displacement 104 5 0 5 10 JA 1 1 1 2 1 2 3 2 1 4 1 4 Time

Consider a force F 151 15 6kN acting in a 3D space at a point A 15 6 20 Determine the following to calculate the moment of this force M about the axis that is defined by the points B 47 29 42 and C 34 21 41 All the coordinates are in mm 1 The distance between the points Band Cis 2 The unit vector along the axis BC is 3 The position vector of A with respect to B r is 4 The moment of the force Fabout the axis BC is mm N mm mm

An infinitely long current carrying wire is placed along the z axis as shown in the figure A current 2 carrying square loop of side length a is placed with its centre at xo 0 0 where xo a If the normal to the loop through its centre is in the x y plane and inclined at angle 37 with the x axis then f g yc 3d d ar TAR 2 34 h gyfe zu GAT 12 gu fh g yu ch a ce quickR MY ZA UGR Gaucht x0 0 0 uma da Z X a 1 K 2 A 1 0 12 3 4 5 4 quz ma qu ya am x 3 H 37 D Magnetic moment of the loop is quan grada sof 0 12 4 31 5 B Magnetic moment of the loop is 4i 33 4 5 qum gacha qof 12 42 3 5 Correct Answer C 2 0 a 1 1 5x0 4 42 3 ukhu Correct Answer The magnitude of torque on the loop is 2 a 11 12 57x0 The magnitude of torque on the loop is

A mirror of radius of curvature 30 cm forms image of size three times that of object The position s of the object may be at a distance from mirror equal to i 10 cm ii 20 cm 1 only ii 3 i ii iii 40 cm 2 only 1 4 0 0

In figure A a stationary spacecraft of mass M is passed by asteroid A of mass m asteroid B of the same mass m and asteroid C of mass 2m The asteroids move along the indicated straight paths at the same speed the perpendicular distances between the spacecraft and the paths are given as multiples of R Figure B gives the gravitational potential energy U t of the spacecraft asteroid system during the passage of each asteroid treating time t 0 as the moment when separation is minimum Which asteroid corresponds to which plot of U t m A B 1 R 2R M R 7 2m Bm Figure A B A 2 U 7 Figure B C C 3 t D B 2

54 An AC voltage source of frequency 50 Hz and amplitude vo is turned on at time t 0 A second voltage source of the same frequency and amplitude is turned on at a later time t 5 ms For both sources the voltage is found to increase immediately after being turned on The instantaneous voltage of the two sources can be represented respectively by vi t and v2 1 where A v t vo sin 100nt and v t vo cos 100m B v t vo sin 100nt and v t vo cos 100m v t Vo cos 100m C vi t vo sin 100nt and D vi t vo sin 100nt and v t Vo cos 100m

A charge particle q m is projected with velocity voi from origin in a region where magnetic field Box k where I is constant If maximum x coordinate of particle is Xm and v is speed at that point then y B v Vo V VO

4 6 52 s 11 Which of the following example does not represents SHM NCERT Pg 358 1 Oscillations of a spring block system 2 Motion of ball bearing inside smooth curved bowl when released slightly away from equilibrium 3 Motion of oscillating mercury column in vertical U tube 4 Rotation of earth about its axis 1 4 8 s 3 1 8 s 14 A particle exec speed of 20 acceleration of oscillation is 1 S 3 E C

Two bodies A and B float in a liquid of 1 density Ps A floats with of its volume 3 3 immersed in the liquid and B floats with 4 of its volume above the liquid level The ratio PA of density is P A B c 1 43 1