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Recent questions in Class12
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JEEMAIN and NEET
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Physics
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Class12
Class12
Electric Charges and Fields
Electrostatic Potential and Capacitance
Current Electricity
Moving Charges and Magentism
Magnetism and Matter
Electromagnetic Induction
Alternating Current
Electromagnetic Waves
Ray Optics and Optical Instruments
Wave Optics
Dual Nature of Matter and Radiation
Atoms
Nucleii
Semiconductor Materials and Electronic Devices
Communication Systems
Experimental Skills in Physics
A conducting wire bent in the form of a parabola $y^2 = 2x$ for $0 \leq x \leq 2$, carries a current $i = 1A$ in anti- clockwise direction as looked from above the $x-y$ plane. There exists uniform magnetic field $-2 \hat k$ Tesla in the region. The magnetic force on the wire is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
force-on-current-wire-in-magnetic-field
difficult
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A particle of specific charge (charge/mass) α starts moving from the origin under the action of an electric field $E_0 \hat i$ and a magnetic field $B_0 \hat k$ . Its velocity at $(x_0, 0, 0)$ is $4 \hat i + 3 \hat j$. The value of $ x_0$ is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-combined-electric-and-magnetic-field
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A current carrying wire $PQ$ is placed $ \perp$ to another wire $RS$ carrying a constant current. If the second wire is free to move, it will have
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
force-between-two-current-wires
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A metallic wire is folded to form a square loop of side $a$. It carries a current $i$ and is kept $ \perp$ to a uniform magnetic field. If the shape of the loop is changed from a square to a circle without changing its length or current, the amount of work done is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A particle having charge $q$ enters a region of uniform magnetic field $B$ directed inwards and is deflected as shown to a distance $d$ above the original line of flight as shown. What is the (magnitude of) momentum of the particle?
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magentic-field
difficult
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
An electron moving with a speed $u$ along the $+ve\: x$ - axis and at $y = 0$ enters a region of uniform magnetic field $\overrightarrow B = -B_0 \hat k $ after sometime with speed $v$ at co-ordinate $ y$, then which exists to the right of the $ y$ - axis. The electron exits from the region
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
easy
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
Velocity and acceleration vector of a charged particle moving in a magnetic field at some instant are $ \overrightarrow V = 3\hat i + 4\hat j\: and\: \overrightarrow B= 2\hat i + x \hat j$. Select the incorrect alternative
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
How much energy must a bombarding proton possess to cause the reaction ? $\;^{7}H_{3}+^{1}H_{1} \to _{4} Be^{7}+_{0}n^{1}$
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 23, 2014
by
yamini.v
1
answer
Two identical coils are placed coaxially. They carry equal currents in the same direction. Then
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-axis-of-circular-current-loop
easy
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
The binding energy of $\;_{17}cl^{35}\;$ nucleus is 298 HeV . Find its atomic mass $\;(_{1}H^{1})\;$ is 1.008143 a.m.u and that of a neutron is 1.008986 a.m.u . Given $\;1amu=931 MeV\;$
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 23, 2014
by
yamini.v
1
answer
A rigid circular loop of radius $ r$ lies in the $x-y$ plane on a flat table and a current $i$ flows through it. At this place, the earth’s magnetic field is $B_x\hat i + B_z \hat k$ . The value of $i$ so that one end of the loop lifts up from the table is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-feild-on-axis-of-circular-current-loop
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A conducting rod of mass $m$ and length $L$ is moving down a smooth incline plane on inclination $ \theta$ with constant velocity $ v$. A current $i$ is flowing in the conductor in a direction perpendicular to the paper inwards. A vertically upward magnetic field $ \overrightarrow B$ exists in space. Its magnitude is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magentic-field
medium
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
Where $\;0.5 A^{0}\;$ x-rays strike a material , the photoelectrons from K shell are observed to move in a circle of radius 23mm in a magnetic fields of $\;2\times10^{-2}T\;.$ Than the binding energy of K-shell electrons is
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 23, 2014
by
yamini.v
1
answer
The dimensions of $ \large\frac{B^2C^2R^2}{2\mu_0}$ where $B$ is magnetic field,$ R$ is resistance and $ C$ is capacitance are
jeemain
aipmt
physics
cbse
class12
ch4
ch5
magnetism-and-matter
difficult
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
Magnetic field at the centre of a circular loop of area $A$ is $B$. Then magnetic moment of the loop is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-axis-of-circular-current-loop
easy
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A proton, a deuteron and an $ \alpha$ - particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If $r_p, r_d$ and $r_{\alpha}$ denote respectively the radii of the trajectories of these particles, then
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
easy
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
A battery is connected between two points $A$ and $B$ on the circumference of a uniform conducting ring of radius $r$ and resistance $R$. One of the arcs $AB$ of the ring subtends an angle $ \theta$ at the centre. The intensity of the magnetic field at the centre due to a constant current in the ring is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-on-axis-of-circular-current-loop
difficult
asked
Feb 23, 2014
by
thanvigandhi_1
1
answer
If the $\;K_{\alpha}\;$ radiation of $\;M_{0}\;(Z=42)\;$ has a wavelength of $\;0.71 A^{0}\;$ , than the wavelength of corresponding radiation of Cu , i. e , $\;K_{\alpha}$ for Cu $\;(z=29)\;$ assuming $\;\sigma=1\;$ .
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 22, 2014
by
yamini.v
1
answer
A perfectly reflecting solid sphere of radius r is kept in the path of a parallel beam of light of large aperture . If the beam carries an intensity I find force exerted by beam on sphere .
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 22, 2014
by
yamini.v
1
answer
A plate of mass 10gm is in equilibrium in air due to force exerted by light beam on plate . Assuming plate is perfectly absorbing the power of beam is :
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 22, 2014
by
yamini.v
1
answer
Light described at a place by the equation $\;\varepsilon=(100 V/m)\;[sin(5\times10^{15} s^{-1})t+sin(8 \times10^{15})t]\;$ falls on a metal surface having work function 2eV . Than maximum kinetic energy of photo electrons will be :
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is : Find saturation current in second case
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 22, 2014
by
yamini.v
1
answer
A circular loop of radius $R$, carrying a current $i$ lies in the $x-y$ plane with its centre at the origin. The total magnetic flux through the $x-y$ plane is
jeemain
aipmt
physics
cbse
class12
ch4
ch5
magnetic-effects-of-current-and-magnetism
q75
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
The magnetic field at the centre of an equilateral triangular loop of side $2L$ carrying a current $i$ is
jeemain
aipmt
physics
cbse
class12
ch4
moving-chare-and-magnetism
magnetic-field-due-to-straight-conductor
medium
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Same current is flowing in three infinitely long wires along positive $x, y$ and $z$ directions. The magnetic field at the point $(0, 0, -a)$ would be
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-due-to-straight-conductor
medium
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A wire of length $\ell$ is bent to form a circular coil of some turns. A current $i$ flows through the coil and is placed in a uniform magnetic field $B$. The maximum torque on the coil can be
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
torque-on-current-loop-in-magnetic-field
difficult
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A conducting rod of mass $m$ and length $\ell$ is placed over a smooth table. A uniform magnetic field is acting perpendicular to the rod. Charge $q$ is suddenly passed through the rod and it acquires a velocity $v$ on the surface, then $q$ is equal to
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-force
difficult
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A charged particle is projected with velocity $ \upsilon_0$ along the positive $x$ - axis. The magnetic field $B$ is directed along negative $z$ - axis for the region $0<x<L$. The particle emerges out at $x = L$ at an angle of $60^{\circ}$ with the direction of projection. Find the velocity with which the same particle is projected at $x=0$ along the $+ve\: x$ - axis so that when it emerges out at $x = L$, the angle made by it is $30^{\circ}$ direction of projection with the
jeemain
aipmt
physics
cbse
class12
ch4
ch5
moving-charge-and-magnetism
motion-in-a-magnetic-field
difficult
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A charge particle moves in a circular path in possible electric and magnetic fields. Which of the following scenarios is possible?
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
In a coaxial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
amperes-circuital-law
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Two parallel wires carry currents $20A$ and $40A$ in the opposite directions. Another wire carrying a current $30A$ parallel to $40A$ is placed mid-way between the two wires. The force on it will be
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
force-between-two-parallel-currents
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
An electric current $\imath$ enters and leaves a uniform circular wire of radius $ \Re$ through diametrically opposite points. A charged particle q moving along the axis of the circular wire passes through the centre at speed $v$. The magnetic force acting on the particle when it passes through the centre is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A ring of mass m, radius R having charge q uniformly distributed over it and free to rotate about its own axis is placed in a region having a magnetic field B parallel to its axis. If the magnetic field is suddenly switched off, the angular velocity acquired by the ring is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
difficult
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Circular arc of a wire of radius R makes an angle of 3π/2 radians at the centre. If a current i flows through it, the magnetic field intensity at the centre of the circle will be
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-on-axis-of-circular-current-loop
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Two parallel connecting wires placed at a distance d apart carry equal currents in the same direction then the intensity of the magnetic field at a point between them will be
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
feild-due-to-parallel-currents
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
The force experienced by a pole of strength $100\: A-m$ at a distance of $0.2 \: m$ from a short magnet of length $10\: cm$ and pole strength $100\: A-m$ on its axial line will be
jeemain
aipmt
physics
cbse
class12
ch5
magnetism-and-matter
bar-magnet
medium
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A uniform magnetic field exists in a region which forms an equilateral triangle of side $a$. The field is perpendicular to the plane of the triangle. A charge $q$ enters the triangle with speed $v$ along the $ \perp$ bisector of one of the sides and comes out along the $\perp$ bisector of the other side. Intensity of the magnetic field is
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
medium
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Consider the following statements \[\] Statement 1: If a charged particle is released in a region of uniform electric and magnetic fields parallel to each other, it will move in a straight line \[\] Statement 2: The magnetic field exerts no force on the particle but electric field does
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-combined-electric-and-magnetic-field
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Consider the following statements \[\] Statement 1: A long straight conductor carrying a current lies along the axis of a current carrying ring. The conductor will not exert any force on the ring \[\] Statement 2: The magnetic field due to a straight conductor coincides with the ring
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
magnetic-field-due-to-circular-current-loop
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
Consider the following statements \[\] Statement 1: A cyclotron cannot accelerate neutrons \[\] Statement 2: Neutrons are neutral
jeemain
aipmt
physics
cbse
class12
ch4
moving-charge-and-magnetism
motion-in-a-magnetic-field
easy
asked
Feb 22, 2014
by
thanvigandhi_1
1
answer
A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is : The efficiency of photoelectron generation will be
jeemain
physics
class12
atoms-and-nuclei
difficult
asked
Feb 22, 2014
by
yamini.v
1
answer
A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is :
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
A small potassium foil is placed (perpendicular to direction of incidence of light ) a distance r (=0.5 m) from a point light source whose output power $\;P_{0}\;$ is 1W . Assuming wave nature of light . how long would it take for foil to soak up enough energy (=1.8eV) from the beam to eject on electron ? (Assume that ejected photoelectron collected its energy from a circular area of foil whose radius equals radius of potassium atom ($\;1.3\times10^{-10}m$))
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
A beam of light consists of 4 wavelength $\;4000A^{0},4800A^{0},6000A^{0}\; and\;7000A^{0}\;,$ each of intensity $\;1.5\times10^{-3}Wm^{-2}\;.$The beam falls normally on an area $\;10^{-4} m^2\;$ of a clean metallic surface of work function 1.9eV . Assuming no loss of light energy the no.of photoelectrons liberated per second is
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
In an experiment on photo electric emission , following observations were made ; (1) Wavelength of incident light = $\;1.98\times10^{-7}m\;$ 2 Stopping potential = $\;2.5 volt\;$. Then kinetic energy of photoelectrons with maximum speed and Thus hold frequency are respectively
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
A small particle of mass m moves in such a way that the potential energy $\;u=ar^2\;$ where a is a constant and r is the distance of particle from origin. Assuming Bohr's model of quantization of angular momentum and circular orbits. Then the radium of $\;n^{th}\;$ allowed orbit is
jeemain
physics
class12
atoms-and-nuclei
medium
asked
Feb 22, 2014
by
yamini.v
1
answer
In a transition to a state of excitation energy 10.19eV , a hydrogen atom emits a $\;4890 A^{0}\;$ photon . Then the binding energy of initial state is :
jeemain
physics
class12
atoms-and-nuclei
easy
asked
Feb 22, 2014
by
yamini.v
1
answer
A single electron orbits around a stationary nucleus of charge +ze , where z is a constant and e is magnitude of electronic charge. It requires 47.2eV to exite the electron from $\;2^{nd}\;$ Bohr orbital to $\;3^{rd}\;$ Bohr orbital. find the atomic no.of element.The wavelength of radiation required remove electron from first Bohr's orbit to infinity is
jeemain
physics
class12
unit11
atoms-and-nuclei
easy
asked
Feb 22, 2014
by
yamini.v
1
answer
A single electron orbits around a stationary nucleus of charge +ze , where z is a constant and e is magnitude of electronic charge. It requires 47.2eV to exite the electron from $\;2^{nd}\;$ Bohr orbital to $\;3^{rd}\;$ Bohr orbital. find the atomic no.of element.
jeemain
physics
class12
atoms-and-nuclei
easy
asked
Feb 22, 2014
by
yamini.v
1
answer
Electrons of energies 12.09 eV can cause radiation to be emitted from hydrogen atom. calculate the principal quantum number of the orbit to which the electron in the hydrogen atom is raised and the wavelength of radiation emitted if it drops back to the ground state .
jeemain
physics
class12
unit11
atoms-and-nuclei
medium
asked
Feb 21, 2014
by
yamini.v
1
answer
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