Physics Questions

In the given circuit with steady current the potential drop across the capacitor must be R www 2 V 2 TT T H 2V C HH 2R www 3 V 3 4 2V 3 COCO

A straight chain consisting of n identical metal balls is at rest in a region of free space as shown In the chain each ball is connected with adjacent balls by identical conducting wires Length of a connecting wire is much larger than the radius r of a ball A uniform electric field E pointing along the chain is switched on in the region Find magnitude of induced charges on one of the end ball a 2m n E b 2 r n 1 IE c 4r n 1 IE d 4 ms n 1 FE

141 A beam of light consisting of red green and blue colours is incident on a right angled prism The refractive index of the material of the prism for the above red green and blue wavelengths are 1 39 1 44 and 1 47 respectively 2015 RSP pait Blue Green Red 45 1

Two spherical conductors A and A of radii r and r are placed concentrically in air The two are connected by a copper wire as shown in figure Then the equivalent capacitance of the system is 1 41 kr 4 5 2 4 r r A r 3 4t 4 4 capacitor must he

A capacitor of capacitance C is charged to a potential V and then isolated A capacitor C is then charged from Co discharged and charged again the process is repeated n times Due to this potential of the larger capacitor is decreased to V then value of C is 1 Co V V 3 Co V V 1 4 Co V V 1 charged 1 uF capacitor are connected in a single loop circuit with a constant 2 C V V 1

Is it possible for the motion of an object along a straight line so that its velocity increases while its acceleration decreases A No because if acceleration is decreasing the object will be slowing down B No because velocity and acceleration must always be in the same direction C Yes an example would be a falling object near the surface of the moon D Yes an example would be a falling object in the presence of air resistance B

An uncharged capacitor of capacitance 100 F is connected to a battery of emf 20V at t 0 through a resistance 1092 then i the maximum rate at which energy is stored in the capacitor is 1 10J s 2 20 J s 3 40J s ii time at which the rate has this maximum value is 1 4 In 2 ms 2 2 In 2 ms 3 In 2 ms 4 5J s 4 3 In 2 ms

In the adjoining diagram two geometrically identical capacitors A and B are connected to a battery Air is filled between the plates of C and a dielectric is filled between the plates of C then We sa 2 9 9 92 C TEK B C 3 9 9 9 A 4 None of these

The figure shows an experimental plot discharging of a capacitor in an RC circuit The time constant T of this circuit lies between AIEEE 2012 Potential difference V in volts 25 20 15 10 5 0 1 150 sec and 200 sec 2 0 and 50 sec 50 100 150 200 250 300 Time in seconds 3 50 sec and 100 sec 4 100 sec and 150 sec

17 A cube made of an insulating material has uniform charge distribution throughout its volume Assuming electric potential due to this charged cube at infinitely distant places to be zero potential at the centre is found to be Vo What is electric potential at one of its corners a Vo c Vo 4 b Vo 2 d VJ8

The flux entering and leaving a closed surface are 5 x 105 and 4 x 105 SI unit respectively then the net charge inside the surface will be 8 85 x 10 7 C 8 85 x 10 7 C 8 85 10 6 C min sec 7 965 10 6 C

The plates of a parallel plate condenser are being moved away with a constant speed v If the plate separation at any instant of time is d then the rate of change of capacitance with time is proportional to 3 d 4 d 1 2

27 Two particles each of mass 100 g and charge 10 C are released on a horizontal plane at a distance 1 0 m from each other Coefficient of friction between the particles and the plane is 0 1 and acceleration of free fall is 10 m s Maximum speed acquired by the particles after they are released is closest to a 2 0 m s c 3 0 m s b 2 8 m s d 4 2 m s

23 Electrostatic potential V at a point on circumference of a circular layer of uniform charge and radius r is given by equation V 4or here o is surface charge density in the layer Which of the following expression correctly represents electrostatic energy stored in the electric field of a similar charge layer of radius R a R c no R3 b R d R

A resistor R and 2uF capacitor in series is connected through a switch to 200 V direct supply Across the capacitor is a neon bulb that lights up at 120 V Calculate the value of R to make the bulb light up 5s after the switch has been closed log 2 5 0 4 AIEEE 2011 1 1 3 10 22 2 1 7 x 10 2 3 2 7 x 10 2 4 3 3 10 rce of voltage 6V is used in an experiment on

If Gravitational field due to uniform thin hemispherical shell at point P is I then the magnitude of gravitational field at Q is Mass of hemisphere is M radius R P 2R 2R

Gravitational field at the centre of a semicircle formed by a thin wire AB of mass m and length as shown in the figure is Gm 2 along x axis Gm TL along y axis 2 Gm along xaxis 22 27Gm 12 along y axis A B B

A 3 mega ohm resistor and an uncharged 1 uF capacitor are connected in a single loop circuit with a constant source of 4 volt At one second after the connection is made what are the rates at which i the charge on the capacitor is increasing 1 4 1 e u C s 2 4e 3 C s 4 1 e C s 3 C S

An uncharged capacitor of capacitance 4 F a battery of emf 12 volt and a resistor of 2 5 MQ are connected in ser The time after which Vc 3V is take n2 0 693 1 6 93 seconds 2 13 86 seconds 3 7 seconds 4 14 seconds ed as shown in the figure with the switch S open When the switch is closed the total amoun

Negative Marks 1 If wrong option is selected A planet moves in an elliptical path with the sun is at one of its foci Select the incorrect statement In QRP path work done by gravity is positive Linear velocity of rotation from Q to P via R decreases O In PSQ path work done by gravity is negative Gravitational potential energy increases in going from P to Q via S S S

An electric dipole of dipole moment p 6 x 10 4 C m is placed in a uniform external electric field of intensity 2x 105 105 N figure The angle between net electric field with external electric field E at point A will be r r 3m O 45 0 37 53 60 A E E as shown in the

In the given figure the capacitors C C C C have a capacitance 4uF each If the capacitor C has a capacitance 10 F then effective capacitance between A and B will be ATIMS 2002 A C C C 0 C 3 6uF B 4 8 F

Negative Marks 1 If wrong option is selected A projectile is projected from ground with initial speed vo at an angle with horizontal If air resistance retardation is ao bv then find the horizontal component of velocity as a function of tin Vo cos a vo cos a e bt Vo sin a ebt Voe bt

Two capacitors C and C are identical except that C has air between the plates and C has a dielectric of dielectric constant F Let q and q are the charges stored when capacitors are fully charged Now the dielectric slab is removed and the corresponding charges are Oq K 1 91 K 92 K 1 K 92 09 2 K 1 92 2K WWW OqK 91 2 and Then

Zero Marks 0 In all other cases A satellite is orbiting around the earth in an orbit in equatorial plane of radius 2Re where Re is the radius of earth If the area on earth this satellite covers for communication purpose in its complete revolution then find N

A sphere of radius R surrounds a point charge Q Net outward flux through of semi vertical angle and of slant length R with vertex at centre is Q 250 1 cos 6 kQ cos e 450 FO 1 cos 0 200 1 cos 6 30

d A parallel plate capacitor of capacitance C is as shown A thin metal plate A is placed between the plates of the given capacitor in such a way that its edges touch the two plates as shown The capacity now be comes 44

A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant K 2 The level of liquid is initially Suppose the liquid level dicreases at a constant speed V the time constant as a d 3 function of time t is Figure 1 68 R 5d 3Vt 2 d 15d 9Vt R 2d 3d V1 9V wla 3 6E R 5d 3Vt www 15d 9Vt R 2d 3d Vt 9V 1

A network is arranged as in Mance s experiment This is used to find the internal resistance of the battery R The resistance of galvanometer and of each of the other three arms is 4 ohms The current in the galvanometer with the key open as well as when it is closed is 0 2A The internal resistance of battery is www B A 402 C 80 S K R A B 20 D 10

A positive charged particle of charge q and mass m is suspended from a point O by a string of length In the space a uniform horizontal electric field E exists The particle is drawn aside so that the string becomes vertical and then it is projected horizontally with velocity v such that the particle starts to move along a circle with same constant speed v A tension in string is mg qE qE B tension in string is mg C kinetic energy of mass is q E 2mg 5 D kinetic energy of mass is mg q E

3 4 x 100 joule A fully charged capacitor has a capacitance C It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity s and mass m If the temperature of the block is raised by AT the potential difference V across the capacitance is AIEEE 2005 2mCAT mCAT 1 2 3 msAT C 4 2msAT C atiualu If the capacitance

T 10 J 2 2 106 J 3 3 106 J 4 4 A charged capacitor is connected with a resistor After how many time constants does the energy of capacitor become 1 10th of its initial value AIIMS 2014 4 2 3 2 1 15 3 0 69 4 none of these with air as a dielectric has capacitance C A slab of dielectric constant K having s in the fir

A conducting wire having cross section area 1 0 mm and length 1 0 km The wire resistivity is 10 2 m at 20 C and its resistance is 2 0 2 at T 320 C Find the temperature coefficient of resistivity in C 1 of the material 1 10 0 x10 3 2 05 0 x10 3 03 3x10 3 4 025 x10 3 5 02 0x10 3

2 Ad 2 d 20 E d The voltage drop across a capacitor connected with a resistance and a battery of 60 V in series after a long time is 1 0 V 2 60 V 3 30 V 4 38 V AIIMS 2012 A 400 DF capacitor is charged with a 100 V battery After disconnecting the battery this capacitor is connected with JAIIMS 2013

A capacitor is charged by a battery The battery is removed and another identical uncharged capacitor is connected in parallel The total electrostatic energy of resulting system NEET 2017 1 decreases by a factor of 2 times 3 increases by a factor of 2 times 2 remains the same 4 increases by a factor of 4 times or of an isolated parallel plate capacitor C having a charge Q and area A

A parallel plate capacitor of area A plate separation d and capacitance C is filled with four dielectric materials having dielectric constant k k k and k as shown in the figure If a single dielectric material is so be used to have the same capacitance C in this capacitor then its dielectric constant k is given by NEET 2016 A 3 A 3 1 k k k k 3k 3 2 3 kk k k k 3 k KA 2 k 1 k3 A13 T d 2 k k k 2k 1 1 1 kk k k 2k4

Two small spheres of masses m and my with charges Q and Q are suspended with insulating threads of lengths L and L such that centres of spheres are in level www If 8 82 then which of the following condition is necessary O m m O m m but Q Q O Q Q OL L2 Q L m 0 m Q

1 2 F 2 4 F 3 6 F A 40 F capacitor in a defibrillator is charged to 3000 V The energy stored in the capacitor is sent through the patient during a pulse of duration 2 ms The power delivered to the patient is AIIMS 2004 1 45 kW 2 90 kW 3 180 kW 4 360 kW pocitors each of capacitance value C are connected as shown in the figure The ratio of capacitance between P TAIIMS 2006

Zero Marks 0 In all other cases Consider a uniform charge distribution with charge density of 2C m throughout in space If a Gaussian sphere has a variable radius which changes at the constant rate of 2 m s then value of the rate of change of total flux is proportional to r r radius of sphere Then find the value of k

1 1 2 2 A parallel plate condenser with a dielectric of dielectric constant K between the plates has a capacity C and is charged to a potential V volts The dielectric slab is slowly removed from between the plates and then reinserted The net work done by the system in this process is AIEEE 2007 1 K 1 CV 3 K 1 CV 4 zero pon the plates has a capacitance of 9 pF The separation between its plates 2 CV K 1 K

A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively If the capacitance between any two adjacent plates is C then the resultant capacitance is AIEEE 2005 n 1 C 2 n 1 CO 3 C 4 nC

Lero Marks 0 In all other cases A lift is going up with an acceleration 2 ms 2 A stone is thrown upward from its floor making angle 15 with horizontal with a speed of 4 3 ms with respect to lift Find the horizontal range in meter inside the elevator Use g 10 m s 15 2ms 4 3ms 10m

4 1 18 3 10 C m 2 8 1 10 C m Find the charge on 2 F 1 18 C 2 25 C 10 V 1 F 3 3 18 10 C m 5 F 2 F 10 V AIIMS 201 3 15 C 4 17 C danger of higher capacity to the condenser of lower capacity

1 45 pF 2 40 5 pF Let C be the capacitance of a capacitor discharging through a resistor R Suppose t is the time taken for the energy stored in the capacitor to reduce to half its initial value and t is the time taken for the charge to reduce to one fourth its initial value Then the ratio t t will be AIEEE 2010 1 1 2 1 2 3 1 4 4 2

Given a square frame of diagonal length 2r made of insulating wires There is a short dipole having dipole moment P fixed in the plane of the figure lying at the center of the square making an angle as shown i figure Four identical particles having charges of magnitude q each and alternatively positive and negative sign are placed at the four corners of the square Select the correct alternative s q Electrostatic force on the system of four charges due to dipole is 6kPq r3 Electrostatics force on the system of four charges due to dipole is 6kPq r3 cos A q Net torque on the system of four charges about the centre of the square due to dipole is zero r 3kPq r Net torque on the system of four charges about the centre of the square due to dipole is r Save

e Each question has FOUR options ONE OR MORE THAN ONE of these four option s is are correct answer s For each question choose the option s corresponding to all the correct answer s Answer to each question will be evaluated according to the following marking scheme Full Marks 4 If only all the correct option s is are chosen Zero Marks 0 If none of the options is chosen i e the question is unanswered In all other cases Negative Marks A particle is projected from a point O with a velocity u at an angle a upwards to the horizontal At a certain point P it moves at right angles to its initial direction It follows that OP makes an angle tan u 2g to the horizontal the distance of P from O is u 2g sin a the time of flight from O to P is u g sin a the velocity of the particle at P is u cot a

Stationary wave is represented by y A sin 100t cos 0 01x where y and A are in mm t in sec and x in m The velocity of the wave 1 1 m s 2 10 m s 3 10 m s In stationary wave 4 not derivable wave to form a s

If a magnetic field H 3a 4a A m exists at a point in free space the magnetic flux density at that point is bold representations are vectors a 3a 2a wb m b 3 768a 5 024a wb m c 3 768a 5 024a uwb m d 3 768a 5 024a wb m

A truck travelling with a uniform velocity begins to accelerate at 3 m s2 for 6 seconds and attains a velocity of 60 m s How much distance was covered by the truck when it was accelerating 17 31

What would be the voltage across C 1 C C V 2 C V C C C Cy V 3 C V C C C AIIMS 20 C V 4 C C C