Neet Physics

Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be: (e being the charge of an electron)

A charge 'q' place at the centre of the line joining two equal charges 'Q'. The system of the three charges will be in equilibrium if 'q' is equal to:

Two pith balls carrying equal charges are suspended from a common point by strings of equal length. The equilibrium separation between them is r. Now the strings are rigidly clamped at half the height. The equilibrium separation between the balls now become :

Point charges +4q , -q and + 4q are kept on the X-axis at points x = 0, x = a and x = 2a respectively. Then :

Suppose the charge of a proton and an electron differ slightly. One of them is -e, the other is . If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then is of the order of: [Given mass of hydrogen  ]

Two metal spheres, one of radius R and the other of radius 2R respectively have the same surface charge density o. They are brought in contact and separated. What will be the new surface charge densities on them?

Two point charges A and B, having charges +Q and-Q respectively, are placed at certain distance apart and force acting between them is F. If 25% charge of A is transferred to B, then force between the charges becomes:

The acceleration of an electron due to the mutual attraction between the electron and a proton when they are $$1.6\dot A$$ apart is:

(Take $$\frac1{4{\mathrm{πε}}_0}=9\times10^9Nm^2C^{-2}$$) $$(m_e=9\times10^{-31}kg,\;e=1.6\times10^{-19}C)$$

Two charged spherical conductors of radius $$R_{1}$$ and $$R_{2}$$ are connected by a wire. Then the ratio of surface charge densities of the spheres () is

An electric dipole is placed angle of 30º with an electric field of intensity $$2\times10^5NC^{-1}$$ . It experiences a torque equal to 4 Nm. Calculate the magnitude of charge on the dipole, if the dipole length is 2 cm.

A, B and C are three points in a uniform electric field. The electric potential is:

A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere respectively are:

In a region, the potential is represented by V(x, y, z) = 6x - 8xy - 8y + 6yz . where V is in volts and x, y, z are in metres. The electric force experienced by a charge of 2 coulumb situated at point (1, 1, 1) is:

If potential (in volts) in a region is expressed as V(x, y, z) = 6xy - y + 2 , the electric field (in N/C) at point (1,1,0) is:

The diagrams below show regions of equipotentials.

A positive charge is moved from A to B in each diagram.

A short electric dipole has a dipole moment of $$16\times10^{-9}cm$$ . The electric potential due to the dipole at a point at a distance of 0.6 m from the centre of the dipole, situated on a line making an angle of 60° with the dipole axis is :

$$(\frac1{4\pi\in_0}=9\times10^9Nm^2/C^2)$$

In a certain region of space with volume $$0.2m^3$$ , the electric potential is found to be 5 V throughout. The magnitude of electric field in this region is :

Twenty seven drops of same size are charged at 200 V each. They combine to from a bigger drop. Calculate the potential of the bigger drop.

The angle between the electric lines of force and the equipotential surface is :

Two hollow conducting spheres of radii $$R_1$$ and $$R_2$$ ($$R_1>>R_2$$) have equal charges. The potential would

A wire of resistance  is stretched to twice its original length. The resistance of stretched wire would be:

Across a metallic conductor of non-uniform cross-section a constant potential difference is applied. The quantity which remains constant along the conductor is:

 The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length, its new resistance will be:

A charged particle having drift velocity of $$7.5\times10^{-4}ms^{-1}$$ in an electric field of $$3\times10^{-10}Vm^{-1}$$ has a mobility in $$m^2V^{-1}s^{-1}$$ of:

The solids which have the negative temperature coefficient of resistance are:

Which of the following graph represents the variation of resistivity ($$\rho$$) with temperature (T) for copper?

Column-I gives certain physical terms associated with flow of current through a metallic conductor.

Column-II gives some mathematical relations involving electrical quantities.

Match Column-I and Column-II with appropriate relations.

Column-1                                    Column-II

(A) Drift velocity                      (i) $$\frac m{m^2\rho}$$

(B) Electrical resistivity          (ii) $$ne\nu_d$$

(C) Relaxation period             (iii) $$\frac{eE}m\tau$$

(D) Current density                (iv) $$\frac EJ$$

A copper wire of length 10 m and radius has electrical resistance of . The current density in the wire for an electric field strength of 10 (V / m) is:

As the temperature increase, the electrical resistance:

Resistance of a carbon resistor determined from colour codes is (22000 plus/minus 5)%)  The colour of third band must be:

The net magnetic flux through any closed surface is :

Under the influence of a uniform magnetic field, a charged particle moves with constant speed vin a circle of radius R. The time period of rotation of the particle:

The magnetic force acting on a charged particle of charge $$-2\mu C$$ in a magnetic field of 2T acting in y direction, when the particle velocity is $$(2\overset\wedge i+3\overset\wedge j)\times10^6ms^{-1}$$, is:

 Two identical bar magnets are fixed with their centres at a distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the center O as shown in the figure.

The force on the charge Qis:

 A uniform electric field and uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron :

A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in uniform magnetic field. What should be the energy of an a-particle to describe a circle of same radius in the same field?

An $$\alpha$$ - particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The wavelength associated with the particle will be:

A proton and an alpha particle both enter a region of uniform magnetic field B, moving at right angles to field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV the energy acquired by the alpha particle will be:

Ionized hydrogen atoms and -particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths $$r_H:r_\alpha$$ will be:

A uniform conducting wire of length 12a and resistance ‘R’ is wound up as a current carrying coil in the shape of

(i) an equilateral triangle of side 'a'.

(ii) a square of side 'a'.

The magnetic dipole moments of the coil in each case respectively are:

In the product vec $$\overrightarrow F=q(\overrightarrow\nu\times\overrightarrow B)=q\overrightarrow\nu\times(B\overset\wedge i+B\overset\wedge j+B_0\overset\wedge k)$$ For q = 1 and overline $$\overrightarrow\nu=2\overset\wedge i+4\overset\wedge j+6\overset\wedge k$$ and vec $$\overrightarrow F=4\overset\wedge i-20\overset\wedge j+12\overset\wedge k$$ what will be the complete expression for overline B:

Current i is flowing in a coil of area A and number of turns N, then magnetic moment of the coil, M is:

A coil in the shape of an equilateral triangle of side / is suspended between the pole pieces of a permanent magnet such that $$\overrightarrow B$$ is in the plane of the coil. If due to a current i in the triangle a torque t acts on it, the side / of the triangle is:

A bar magnet having a magnetic moment of $$2\times10^4\;JT^{-1}$$ is free to rotate in a horizontal plane. A horizontal magnetic field $$B=6\times10^{-4}\;T$$ exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is:

A bar magnet, of magnetic moment $$\overrightarrow M$$ , is placed in magnetic field of inductionc $$\overrightarrow B$$ . The torque exerted on it is :

A short bar magnet of magnetic moment  placed in a uniform magnetic field of 0.16 T. The magnet is in stable equilibrium when the potential energy is:

A magnetic needle suspended parallel to a magnetic field requires $$\sqrt3J$$ of work to turn it through 60°. The torque needed to maintain the needle in this position will be:

A bar magnet of magnetic moment M is placed at right angles to a magnetic induction B. If a force F is experienced by each pole of the magnet, the length of the magnet will be:

A bar magnet of length 'l' and magnetic dipole moment 'M' is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be:

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole moment . Which configuration has  highest net magnetic dipole moment?

In a coil of resistance , the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in weber is:

A coil of resistance is placed in a magnetic field. If the magnetic flux $$\phi(wb)$$ linked with the coil varies with time  t(sec) as $$\phi=50t^2+4$$ The current in the coil at t =2 sec is:

A current of 2.5. A flows through a coil of inductance 5H. The magnetic flux linked with the coil is:

A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is:

A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is:

An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current if any, induced in the coil?

A long solenoid of diameter 0.1 m has $$2\times10^4$$ turns per metre. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4 A in 0.05 s. If the resistance of the coil is . The total charge flowing through the coil during this time is :

A 800 turn coil of effective area $$0.05\;m^2$$ is kept perpendicular to a magnetic field $$5\times10^5T$$. When the plane of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be:

A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at  If the vertical component of earth's magnetic field at that place is 2 and electrical resistance of the coil is , then the maximum induced current in the coil will be

A square loop of side and resistance  is placed in a magnetic field of 0.5 T. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is:

In an a.c. circuit, the r.m.s. value of current, is related to the peak current, by the relation:

In an A.C. circuit with voltage V and current I the power dissipated is:

In an a.c. circuit the emf (e) and the current (i) at any instant are given respectively by:

$$e=E_0\;\sin\;\omega t$$

$$I=I_0\;\sin\;(\omega t-\phi)$$

The average power in the circuit over one cycle of a.c. is:

The rms value of potential difference V shown in the figure is:

 In an ac circuit alternating voltage  volts is connected to a capacitor of capacity . The rms value of the current in the circuit is:

The instantaneous values of alternating current and voltage in a circuit are given as:

The average power in watts consumed in the circuit is:

The current (I) in the inductance is varying with time according to the plot shown in figure.

A small signal voltage $$V(t)=V_0\sin\;\omega t$$  is applied across an ideal capacitor C:

A  capacitor is connected to a 200 V, 50 Hz ac supply. The rms value of the current in the circuit is, nearly:

The peak voltage of the ac source is equal to:

Light with an energy flux of falls on a perfectly reflecting surface at normal incidence. If the surface area is . the average force exerted on the surface is:

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is: c = Velocity of light)

Out of the following options which one can be used to produce a propagating electromagnetic wave?

In an electromagnetic wave in free space the root mean square value of the electric field is . The peak value of the magnetic field is:

An em wave is propagating in a medium with a velocity vec . The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along :

The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is: ( c = speed of electromagnetic waves)

For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?

A capacitor of capacitance 'C, is connected across an ac source of voltage V, given by $$V=V_0\sin\;\omega t$$. The displacement current between the plates of the capacitor, would then be given by:

When light propagates through a material medium of relative pemittivity and relative permeability , the velocity of light, u is given by: (c-velocity of light in vacuum)

In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of $$2.0\times10^{10}Hz$$ and amplitude $$48Vm^{-1}$$ Then the amplitude of oscillating magnetic field is: (speed of light in free space = $$3\times10^8m/s$$)

A light ray falls on a glass surface of refractive index at an angle . The angle between the refracted and reflected rays would be:

Light travels a distance x in time $$t_1$$, in air and 10x in time $$t_2$$ in another denser medium. What is the critical angle for this medium?

Ray optics is valid, when characteristic dimensions are:

If two mirrors are kept inclined at 60° to each other and a body is placed at the middle, then total number of images formed is:

A person is six feet tall. How tall must a vertical mirror be if he is able to see his entire length?

A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its end closer to the pole is 20 cm away from the mirror. The length of the image is:

Two plane mirrors are inclined at 70°. A ray incident on one mirror at angle after reflection falls on second mirror and is reflected from there parallel to first mirror

The value of  is:

Match the corresponding entries of column-1 with column-2: (Where m is the magnification produced by the mirror)

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source I. When the mirror is related through a small angle , the spot of the light is found to move through a distance y on the scale. The angle is given by:

An object is placed on the principal axis of a concave mirror at a distance of 1.5 f (f is the focal length). The image will be at:

In Young's double slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes:

Young's Double Slit Experiment (YDSE)

In a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is:

Which one of the following phenomena is not explained by Hygens construction of wavefront ?

Interference is possible in :

Ratio of intensities of two waves are given by 4: 1. Then the ratio of the amplitudes of the two waves is:

Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observer will see:

Colours appear on a thin soap film and on soap bubbles due to the phenomenon of:

The periodic waves of intensities $$I_{1}$$ and $$l_{2}$$ pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:

The interference pattern is obtained with two coherent light source of intensity ratio n. In the interference pattern, the ratio  will be:

For Young's double slit experiment, two statements are given below:

Statement-I: If the screen is moved away from the plane of slits, angular separation of the fringes remains constant. 

Statement-II: If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases.

In the light of the above statements, choose the correct answer from the options  given below: