Recent questions and answers in Physics

Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be :

answered Dec 17, 2018 by devarajulunbpl9

1 answer

The energy required to charge a parallel plate condenser of plate separation d and plate area of cross - section A such that the uniform electric field betwen the plates is E, is :

answered Dec 1, 2018 by shanukumar9211

1 answer

The ground state energy of hydrogen atom is -13.6eV. When its electron is in the first excited state, its excitation energy is :

answered Nov 28, 2018 by madhavprasad25031999

1 answer

Three closed vessels A , B and C are at the same temperature T and contain gases which obey maxwellian distibution of velocities . Vessel A contains only $\;O_{2}\;$ . B only $\;N_{2}\;$ and C a mixture of equal quantities of $\;O_{2}\;$ and $\;N_{2}\;$ . If the average speed of $\;O_{2}\;$ molecules in vessel A is $\;V_{1}\;$ , that of $\;N_{2}\;$ molecules in vessel B is $\;V_{2}\;$ the average speed of the $\;O_{2}\;$ molecules in vessel C will be

answered Nov 16, 2018 by kajalrahangdale357

2 answers

The main purpose of modulation is to

answered Nov 2, 2018 by chetanwane

2 answers

The capacitance of parallel plate capacitor does not depend upon

answered Oct 21, 2018 by balu.rathod7585

3 answers

Three capacitors, each of capacitance C are connected to a battery of voltage V. When key K is closed, the charge which will flow through the battery is (see figure).

answered Oct 16, 2018 by nitishnetha

1 answer

A galvonometer of resistance $ 50 \Omega$ is connected to a battery of 3V along with a resistance of $ 2950 \Omega$ in series. A full scale deflection of 30 divisions is obtained in the galvonometer. In order to reduce this deflection to 20 divisions, the resistance in series should be :

answered Oct 13, 2018 by lecturernlmgowda

1 answer

Two blocks are in contact on a frictionless table. One has mass m and another mass '2m'. A force F is applied on '2m' as shown. Now the force F is applied on 'm' from right. In the two cases respectively the ratio of force of contact between the blocks is

answered Oct 3, 2018 by pushpadubey555567123

2 answers

A uniform circular disc of radius r is placed on a rough horizontal surface and given a linear $w_0$ as shown. The disc com,es to rest after moving some distance to the right. It follows that

answered Sep 4, 2018 by gopal.churu2010

2 answers

A roller coaster is designed such that riders experience " weightlessness" as they go round the top of a hill whose radius of curvature is 20m. The speed of the car at the top of the hill is between

answered Aug 17, 2018 by abhishekdogra878

1 answer

A block takes twice as much time to slide down a rough $45^{\large\circ}$ inclined plane as it takes to slide down an identical smooth $45^{\large\circ}$ inclined plane.The coefficient of kinetic friction between the block and the rough inclined plane is

answered Aug 9, 2018 by aloksingh2082000

2 answers

A metallic resistor is connected across a battery. If the number of collisions of free electrons with the lattice is somehow decreased in the resistor, the current will

answered Jul 18, 2018 by ashishkhatua444

2 answers

Hot air balloon is an application of what law?

answered Jul 12, 2018 by excellate39

3 answers

As the temperature of a metallic conductor is increased, the product of resistivity and conductivity

answered Jul 4, 2018 by upretipramod44

2 answers

A particle is projected perpendicular to a uniform magnetic field. The area bounded by the trajectory of the particle is directly proportional to

answered Jun 2, 2018 by kasirnazir620

2 answers

The motion of a sphere moving on a rough horizontal surface change from pure sliding (without rolling) to pure rolling (with out slipping) . In this process, the force of friction. 1) initially acts opposite to the direction of motion and later in the direction of motion. 2) causes linear retardation 3) causes angular acceleration 4) stops acting when pure rolling begins. Which of the following is correct?

answered Apr 25, 2018 by blsaketh33

1 answer

A solid sphere of mass m is lying at rest on a rough horizontal surface. The coefficient of friction between the ground and sphere is $\mu$. The maximum value of F, so that the sphere will not slip is equal to

answered Apr 19, 2018 by jainnanu010

2 answers

A body covers a certain distance x in equal thirds - the first third of distance with speed v$_1$, the second third with a speed of v$_2$ and the last third with a speed of v$_3$. What is the average speed of the body over time?

answered Apr 16, 2018 by ushapattima

2 answers

A spherical body of radius R rolls on a horizontal surface with linear velocity $V$. Let $L_1$ and $L_2$ be the magnitude of angular momentum of the body about the centre of mass and point of contact P respectively. a) $L_2=L_1$ if radius of gyration $k=R$ b) $L_2=2L_1$ for all cases. c) $L_2 > 2L_1$ if radius of gyration $K < R$ d) $L_1> L_2$ if radius of gyration $ K > R$ Which of the following is correct?

answered Apr 9, 2018 by kingsumit011

1 answer

Which of the following does not represent Boyle's law?

answered Mar 28, 2018 by mahawarravi036

3 answers

A ball is dropped from a height of h from ground. If the coefficient of restitution is e, the height to which the ball goes up after it rebounds for the nth time is

answered Mar 5, 2018 by yashuvats.42

2 answers

A man spinning in free space changes of his body e.g by spreading his arms and curling up. By doing this, he can change his 1) moment of inertia 2) angular momentum 3) angular velocity 4) rotational kinetic energy in this Which of the following is correct?

answered Feb 28, 2018 by priyanka.c

2 answers

The velocity of electromagnetic radiation in a medium of permittivity $ \in_0$ and permeability $ \mu_0$ is given by :

answered Jan 16, 2018 by jk6765001

2 answers

A person looks in to a spherical mirror . The size of image of his face is twice the actual size of his face. If the face is at distance 20 cm then find the radius of curvature of mirror.

answered Dec 1, 2017 by br.singh21914

2 answers

A horizontal disc rotates freely about a vertical axis through its centre. A ring, having the same mass and radius as the disc , is now gently placed on the disc. After some time, the two rotate with a common angular velocity. 1) some friction exits between the disc and the ring 2) the angular mometum of disc plus ring is conserved. 3) the final common angular velocity is $\large\frac{2}{3}$ rd of the initial angular velocity of disc. 4) $\large\frac{2}{3}$ rd of the initial kinetic energy is converted to heat. Which of the following is correct?

answered Oct 8, 2017 by vlalithambica

1 answer

From the top of a building 40 m tall, a ball a thrown vertically upwards with a velocity of $10\; ms^{-1}$ After how long will the ball hit the ground?

answered Aug 13, 2017 by sl0224422

2 answers

A person sitting in an open car moving at constant velocity throws a ball vertically up into air. The ball falls

answered Jul 13, 2017 by akashrao0005

2 answers

Minimum size of plane mirror, required to see full image of an observer is :

answered Jun 20, 2017 by parthgite94

2 answers

Find the dimension of physical quantity $X$ in the equation $Force=\large\frac{X}{Density}$

answered May 14, 2017 by muskaans095

2 answers

In the circuit as shown in the figure what is the potential difference between P and Q.

answered May 13, 2017 by nikunjjain285

1 answer

The trajectory of a projectile in a vertical plane is $y=ax-bx^2$ where $a$ and $b$ are constants. The maximum height attained by the particle and the angle of projection from horizontal are

answered Apr 24, 2017 by vipul.saini442

2 answers

Two identical particles , each having a charge of $\;2\times10^{-4}\;C\;$ and mass 10g are kept at a separation of 10 cm and released . What would be the speeds of the particles when the separation becomes large ?

answered Apr 19, 2017 by mahajanmridul1997

2 answers

electric charge Q,Q and -2Q resp. are placed at the three corners of an equilateral triangle of side a . magnitude of the elctrical dipole moment of the system is

answered Mar 23, 2017 by abdulsalamottathil

2 answers

a body is projected vertically upward from the earths surface such that it reaches a height equal to the radius of the earth above its surface.find the velocity of projection

answered Feb 3, 2017 by prekshu.02

1 answer

A 150m long train is moving with uniform velocity of 45km / h. The time taken by train to cross the bridge of length 850m is ?

answered Jan 29, 2017 by suchala2002

3 answers

Dhoni throws his bat vertically upwards with an initial velocity of $26.2\;m/s$ Determine the height to which the bat will rise above its initial height.

answered Aug 14, 2016 by donkadasnd

2 answers

Two identical charged spheres are suspended by strings of equal length . The strings make an angle of $\;60^{0}\;$ with each other . When suspended in a liquid of density $\;0.5 g/cc,\;$ the angle remains the same . The dielectric constant of the liquid is [density of material of sphere is $\;1.5 g/cc\;$]

answered Jun 24, 2016 by dongrearchit

2 answers

Two identical ladders are arranged as shown in the figure, resting on a horizontal surface. Mass of each ladder is M and length L. A block of mass m hangs from the apex point P. If the system is in equilibrium, find direction and magnitude of friction force acting at A or B.

answered Apr 1, 2016 by vijayalakshmi.r

1 answer

A particle of mass m is travelling with a constant velocity $\overrightarrow {V} =V_0 \hat i$ along the line $y=b,z=0$. Let $dA$ be the area swept out by the position vector from the origin to the particle in time at end L be the magnitude of angular momentum of particle about orgin at any time t. Then 1) L= constant 2) $\large\frac{dA}{dt}=\frac{L}{m}$ 3) $\large\frac{dA}{dt}= \frac{2L}{m}$ 4) $\large\frac{dA}{dt}=\frac{L}{2m}$ Which of the following is correct?

answered Apr 1, 2016 by vijayalakshmi.r

1 answer

If the error in the measurement of radius of a sphere is 2%, then the error in the determination of volume of the sphere will be :

answered Feb 12, 2016 by _1

1 answer

Six equal resistance are connected between point P,Q,R as shown in the fig. Then the net resistance will be maximum between

answered Feb 8, 2016 by meena.p

1 answer

A solenoid carrying a current supplied by a DC source with constant emf contains iron rod inside it. when the rod is pulled out of the solenoid , then the current in the solenoid will

answered Feb 8, 2016 by meena.p

1 answer

In an AC circuit V and I are given by $V=100 \sin (100 t) volt \; I =100 \sin (100 t +\large\frac{\pi}{3})amp$ the power dissipated in the circuit is

answered Feb 8, 2016 by meena.p

1 answer

An aeroplane is moving north horizontally , with a speed of $200 ms^{-1}$ ,at a place where the vertical component of the earth's magnetic field is $ 0.5 \times 10^{-4}\;T$ .What is the induced e.m.f set up between the tips of the wings, if they are 10 m apart ?

asked Feb 8, 2016 by meena.p

1 answer

If vectors $\overrightarrow{A} = \cos wt \hat i +\sin w + \hat j$ and $\overrightarrow{B} = \cos wt/2 \hat i +\sin wt/2 + \hat j$ are functions of time , then the value of t at which are orthogonal to each other is

asked Feb 8, 2016 by meena.p

1 answer

A child is standing with his two arms outstretched at the center of a turntable that is rotating about its central axis with an angular speed $w_0$ Now the child folds his hands back so that the moment of inertia becomes 3 times the intial values.The new angular speed is

asked Feb 8, 2016 by meena.p

1 answer

Three planets of same density and with radii $R_1,R_2$ and $R_3$ Such that $R_1=2R_2=3R_3$, have gravitational fields on the surfaces $E_1,E_2,E_3$ and escape velocities $v_1,v_2,v_3$ respectively ,then

asked Feb 8, 2016 by meena.p

1 answer

A block of wood floats in water with $\large\frac{4}{5}$ th of its volume submerged , but it just floats in a liquid . What is the density of the liquid ?

asked Feb 8, 2016 by meena.p

1 answer

A clock with an iron pendulum beeps correct time at $15 ^{\circ}c$ what will be the error in time per day , if the room temperature is $20^{\circ}$?

asked Feb 8, 2016 by meena.p

1 answer

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