Basic Physics Questions and Answers

Three samples of the same gas A B and C y 3 2 have equal volume initially Now the volume of each sample is doubled For A the process is adiabatic for B it is isobaric and for C the process is isothermal If the final pressures are equal for all the three samples the ratio of their initial pressures is a 2 1 2 b 2 2 1 2 c 2 1 2 d 2 2 1

A disc of radius r 2 cm attached with a horizontal axle OA is rolling without sliding on a circular track of radius R 10 am as shown In the process the centre of the disc moves with a constant speed v 10 cm s Find the angular acceleration in rad s of the disc R O 0

In figure a block of mass m is released from rest when spring was in its natural length The pulley also has mass m but friction less Suppose the value of m is such that finally it is just able to lift the block M up after releasing it www M Rod String A The weight of m required to just lift M is Mg 2 Mg B The tension in the rod when m has an acceleration is zero 2 C The normal force acting on M when m has zero acceleration is UP

A body of mass M is moving on a circular track of radius r in such a way that its kinetic energy k depends on the distance travelled by the body s according to relation k s where is a constant The angular acceleration of the particle is A C Br M M r B B D Br M B Mr

Explain correct reason P Assertion Practically a voltmeter will measure the voltage across the battery but not its EMF Reason EMF of a cell is measured with th help of a potentiometer

4 A wooden block is taken to the bottom of a deep calm lake of water and then released It rises up with a Neglect viscous force 1 Constant velocity 2 Constant acceleration 3 Decreasing acceleration 1 Increasing acceleration

63 A short dipole of dipole moment p is placed with its neetquestion perpendicular to a long thin uniformly charged with linear charge density at a distance r Find the force acting on the rod due to field of dipole p 1 2 2 p r

A small steel bail B is at rest on the edge of a table of height h Another identical steel ball A is tied to a light string of length L 1 0 m and is released from the position shown so that it swings like a pendulum At the lowest position of its path it hits the ball B which is at rest Ball B flies off the table and hits the ground in time t After collision the ball A keeps moving for a time t before coming to rest for the first time Find the value of h if t t Collision between the balls is head on and coefficient of restitution is e 0 995 A L 1m L TTI LUILL O B

A man of mass m is stationary by pulling a light string The string makes an angle of 37 with the vertical wall as shown in the figure The coefficient of static friction between legs of man and the vertical wall is 0 5 Find the maximum value of m m M 37

Two bodies A 30 kg and B 50 kg tied with a light string are placed on a frictionless table A force F acting at B pulls this system with an acceleration of 2m s Find the tension in the string in newton A boat is traveling east at 12 m s A flag flaps at 53 N of W at the bow of the boat Another flag on shore

thin glass plate of thickness t 2 3 being the wavelength of incident light and refractive index 1 5 is inserted between the low it and the screen in Young s double slit experiment both slits are giving light of equal intensity If the intensity at a point on the screen quidistant from the slits is I then Intensity at the same point before introduction of glass plate was 31 2 Intensity at the same point before introduction of glass plate was 41 3 Central maximum will be in the lower half of screen after introduction of glass plate Shape of fringes will be straight line on the screen

uniform but time varying magnetic dB dt field increasing at a constant rate as shown A charged particle having charge q and mass m is kept in equilibrium at the top of a spring of spring constant K in such a way that it is on the horizontal line passing through the centre of the magnetic field as shown in the figure The compression in the Here in question it is given as a horizontal cylindrical shape but here a circular shape is given spring will be OR CO I m confused plzz explain me this question q K

As shown in the figure given below in the case 1 the mass m is pulled with the help of contact force FN and in the case 2 the mass m is hung with another block of weight F N and the system is stationary m CASE 1 VFN m CASE 2 FN 1 In both the cases the magnitude of acceleration of both the blocks are same when they are released from the rest 2 In case 2 magnitude of acceleration of the F mg mg F block of mass m is g from rest 3 In case 2 magnitude of acceleration of block F g of mass m is when released from mg F rest when released 4 In case 2 magnitude of acceleration of block F m g of mass m is when released from

When an object is at distance x and y from a lens a real image and a virtual image is formed respectively having same magnification The focal length of the lens is O xty 02 y O xy OF U

Why electron of phosphorus doped in silico n can ionise by visible light in n type of Solar cell because energy of visible light is less th an ionisation energy of phosphorus then ho w it can possible

Numeric 9 Your car is stuck in a mudhole You are alone but you have a long strong rope Having studied physics you tie the rope tautly to a telephone pole and pull on it sideways as shown Find the force exerted by the rope on the car in N when the angle 0 is 3 and you are pulling with a force of 314N but the car does not move Telephone pole

Rain drops of some initial mass start falling rest In their way they gain from clouds with a rate proportional to the product of instantaneous ma and instantaneous velocity with proportionality constant being 2 5 SI un Find the terminal attained by drops in m s Take Om 10m s

1 Find the value of the unknown resistance X in the circuit Fig 2 76 if no current flows through the section AO Also calculate the current drawn by the circuit from the battery of emf 6 V and negligible internal resistance A B 2 52 www hos www 6 V ww o 10 2 www XQ Fig 2 76 60 2 4 2 www C

BPH2101 PHYSICS REMAINING TIME HOURS MINUTES SECONDS 1 47 12 41 In an electromagnetic wave in free space the rms value of the electric field is 3Vm 1 The peak value of the magnetic field is Ozo 10 8 T 01414 10 1 02828 101 41 QUA

X Acceleration time graph of a particle moving 38 along X axis is as shown The particle will have the velocity same as its initial velocity at time a m s 10 1 8 1 10 s 2 10 3 s 3 10 5 3 s 4 10 2 3 s Figure shows the displacement time curve of the 39 ren f a m s 10 1 10 s 3 10 5 3 s far face t 1 s 2 10 3 s 4 10 2 3 s

Light of wavelength 6000 falls normally on a thin wedge shaped film of refractive index 1 4 forming fringes that are 2 mm apart Find the angle of the wedge a 1 50 x 104 rad b 1 07 x 104 rad c 1 75 x 10 5 rad d 1 00 10 5 rad 4 2

In a radioactive decay reaction 27 A B C Select correct alternative s at the instant the number of the particles of B is maximum A Activity of A is equal to activity of B B No of atoms of A is 2 times of B C Activity of A is more than activity of B Activity of R is maximum

A wedge whose curved surface is parabolic in shape and has equation x when a block is at the bottom of wedge and is located at 0 0 4y starts accelerating with acceleration The maximum height attained by the block assume the curved surface is sufficiently long m s g A 1m C 4m The ratin B 2m D 8m Va PT I PH JEE Main 20 a g m s 0 0

O A cylinder of radius 4cm and height 10cm is immersed in two liquids as shown Specific gravity of oil is 0 5 2cm of cylinder is in the air Select the incorrect statement Neglect atmospheric pressure Force exerted by oil on the cylinder is zero Force exerted by water on the cylinder is 0 96 newton Force exerted by both water and oil is 1 14 m newton Frequency of oscillation does not depend on density of oil if cylinder is displaced slightly 2cm 4cm

A rope lies on a table such that a part of it hangs down the table When the length of hanging part is 1 5 of entire length the rope just begins to slide The coefficient of friction between the rope and the table is 1 1 4 2 1 6 3 1 5 4 3 4

22 If a rigid body is rotating about an axis with a constant velocity then 2019 a Velocity Angular velocity of all particles will be same Velocity Angular velocity of all particles will be different Velocity of all particles will be different but angular velocity will be same Angular velocity of all particles will be different but velocity will be same b c d

Rtane m chain of mass m and length I is lying on a horizontal table with one third of its length hanging over the edge of the table If the chain is in limiting equilibrium what is the coefficient of friction for the contact between the table and chain kom 2 3 1 1 ell 2 4 ee 1 13 3 3

A disc of mass m and radius 2R has another disc of mass 2m and radius R 2 kept on it at O The system is given an angular velocity about a vertical axis passing through O The friction between discs is negligible and smaller disc is free to rotate about O Find the angular momentum in M KS unit of system at f about a vertical axis passing through O 090 Given that m 300 gm ca 8 rad s and R 1 2m 2R

A 0 300 mC charge blue charge and a 0 200 mC charge red charge are positioned as shown in the diagram below How much work is done by external forces in moving a 8 15 C charge from point a to point b in units of joules 12 0 cm 12 0 cm 15 9 cm 6 0 cm 12 0 cm b

If mass energy equivalence is taken into account when water is cooled to form ice the mass of water should mc where Note The mass energy of an object is the energy equivalent of its mass as given by E m mass of object c speed of light A increase C decrease B remain unchanged D first increase then decrease

Choose the correct statement s from the following A A temperature change which increases the length of a steel rod by 0 1 will increase its volume by nearly 0 3 B C D The specific heat of a gas is different when heated at i constant pressure and ii the constant volume The thermal conducitvity of air being less than that for wool we prefer wool to air for thermal insulation When the distance between two fixed points is measured with a steel tape the observed reading will be less on a hot day than on a cold day Statement b is also correct 1 When a solid is heated at constant pressure it does expand a little and some heat is required for doing the mechanical work associated with this expansion i When a solid is heated at constant volume only internal energy changes and no heat is required for doing the mechanical work The difference between the two specific heats at constant pressure and at constant volume is small enough to be generally neglected for solids and liquids This difference is large for gases Statement c is incorrect The thermal conductivity of air is less than that of wool Yet we prefer wool which traps pockets of air between its fibres There air pockets cannot carry heat by convection either Statement d is correct because of the expansion of steel tape on a hot day the markings on the tape would be farther apart than on a cold day I did not understand why c is not corr ect Is there any other explanation for t his answer for c to be false I had asked this qn earlier but i was not able to understand and I accidentally cli cked YES for the feedback So could you pls explain once more The qn and answer both says that ther mal conductivity of air is less than that

A semi infinite line charge of linear charge density has the shape as shown in the figure Portion ABC forms three fourth of a circle of radius R while the straight portion from C to infinity is parallel to BOA The field at the centre of circle O is A 2 2 ER C zero 2 B 2 ER D None of these B R C 90 A

Please add some explanations wherever their is a use of s gn convention in magnification formula and mirror formul a 7 A concave mirror of focal length 18 cm forms an erect image three times the size of the object How far is the object from the mirror 1 36 cm 3 15 cm A naint ahinnt in plannd at dintonon of on 2 18 cm 4 12 cm

the correct statement C4 IPL Physics 1 a A hack saw blade which is fixed at one end will produce feeble sound when it is vibrated with small force because it perform vibrations with less amplitude b A hack saw blade which is fixed at one end will produce louder sound when it is vibrated with large force because it perform vibrations with smaller amplitude c A hack saw blade which is fixed at one end will produce louder sound when it is vibrated with small force because it perform vibrations with less amplitude d A hack saw blade which is fixed at one end will produce feeble sound when it is vibrated with large force because

72 Choose the correct option for the p V curve shown below P 3P SPV D A a For the process ABCD AU 0 B

After driving a portion of the route the taptap is fully loaded with a total of 23 people including the driver with an average mass of 60 kg kg per person In addition there are three 15 kg kg goats five 3 kg k g chickens and a total of 25 kg k g of bananas on their way to the market Assume that the springs have somehow not yet compressed to their maximum amount How much are the springs compressed k 2 9x10 4

A person is moving in a circle of radius r with constant speed V The change in velocity in moving from A to B is 1 2V cos 40 2 2V sin 40 3 2V cos 20 4 2V sin 20 al brexinut molage 40 zol O r B A

A circular disc rotates at 60 rpm about an axis passing through its centre A coin of 18 g is placed at a distance of 8 cm from the centre of the disc Calculate the cen 0 057 N trifugal force on the coin

A block of mass m 2 kg sliding on a frictionless platform lands on cart B of mass M 10 kg 1 3 If initial speed of block is 5 m s between block cart is inelastic with Distance from point B where block m will move to rest w rt block M 1 12 1 e m m l m 3m The horizontal floor below the cart is frictionless Coefficient of friction between cart block is 0 5 Collisio A B M

The shape of the curve representing the relation between the speed and kinetic energy of a moving object is a parabola b ellipse c straight line with positive slope d straight line with negative slope

If I is the intensity of the principal maximum in 7 the single slit diffraction pattern then what will be its intensity when the slit width is doubled Io 1 I 2 3 21 4 41 chet forff fadd ff 3fe fra 1 at fff s yf aftaran guft 1 I 2 1 0 3 210 4 41

36 A block of mass mis released from a height R on the frictionless incline as shown The incline leads to a circle of radius R 2 The maximum height attained by the block is R R 2

A light of wavelength 6000A is coming from a star What is the limit of resolution of a telescope whose objective lens has a diameter of 100 inch A 4 2 10 5 rad B 2 9 10 7 rad D 4 0 x 10 7 rad C 1 5 x 104 rad

3 ssm Due to continental drift the North American and European continents are drifting apart at an average speed of about 3 cm per year At this speed how long in years will it take for them to drift apart by another 1500 m a little less than a mile

There is a small source of light at some depth below the surface of water refractive index in a tank of large cross sectional surface area Neglecting any reflection from the bottom and absorption by water percentage of light that emerges out of surface is nearly Use the fact that surface area of a spherical cap of height h and radius of curvature r is 27rh A 17 B 34 C 50

A concave lens of focal length 20 cm 13 placed in contact with a plane mirror acts as a 1 Convex mirror of focal length 10 cm 2 Concave mirror of focal length 40 cm 3 Concave mirror of focal length 60 cm 4 Concave mirror of focal length 10 cm 20 cm Hade du at yun e ven chat si 48 1 10 cm 2 40 cm 3 60 cm 4 10 cm cada an

particle of charge q and mass m starts moving from the origin under the action of an electric field E E and B Bo with a velocity v vo The speed of the particle will become muo qEo mvo 29E0 muo vo after a

semi circular current loop is placed in a uniform magnetic field of 0 5T in the plane of the paper as shown If the radius of loop is 1 m the magnetic force on the loo X X X P X X X X x 2A X X X X X X X X 2A X X 4N up the plane of the paper 4N down the plane of the paper N down the plane of the paper X BX X X X

11 In a tug of war contest two men pull on a horizontal rope from opposite sides The winner will be the man who a exerts greater force on the rope b exerts greater force on the ground c exerts a force on the rope which is greater than the tension in the rope d makes a smaller angle with the vertical

5 ix Figure 2 78 shows five large parallel plates kept at equal separation d and each of plate area A with some wire connections Find out equivalent capacitance between terminals X and Y X Y