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Recent questions tagged difficult
Questions
What is the minimum energy that must be given to a H- atom in ground state so that it can emit an $H_{\gamma}$ in Balmer series? If the angular momentum of the system is conserved what would be the angular momentum of such $H_{\gamma}$ proton ?
cbse
class12
physics
ch12
sec-b
exemplar
difficult
asked
Jul 8, 2016
by
meena.p
1
answer
The energy of an electron in an excited hydrogen atom is $-3.4 \;ev$ calculate the angular momentum of the electron according to Bohr's theory .
cbse
class12
physics
ch12
sec-b
additional
difficult
asked
Jul 8, 2016
by
meena.p
1
answer
Two monochromatic beams A and B of equal intensity I , hit a screen . The number of photons hitting the screen by beam A is twice that by beam B. Then What inference can you make about their frequencies ?
cbse
class12
physics
ch11
sec-a
exemplar
difficult
asked
Jul 4, 2016
by
meena.p
0
answers
The de- Broglie wave length of a photon is twice the de- Broglie wave length of an electron. The speed of the electron is $v_e = \large\frac{c}{100}$ . Then
cbse
class12
physics
ch11
sec-c
exemplar
difficult
asked
Jul 4, 2016
by
meena.p
1
answer
Estimate the speed with which electron emitted from a heated cathode of an evacuated tube impinge on the anode maintained at a potential difference of $500\;v$ , with respect to the cathod . Ignore the small initial speeds of the electrons . The specific charge of the electron (ie) its $\large\frac{e}{m}$ is given to be $1.76 \times 10^{11}\;kg^{-1}$ use the same formula you employ to obtain electron speed for an anode potential of 10 Mv. Do you see what is wrong ? In what way in is the formula to be modified ?
cbse
class12
physics
ch11
ncert
difficult
sec-e
asked
Jun 24, 2016
by
meena.p
1
answer
A ray of light from a rarer medium strikes a denser medium as shown in the figure . The reflected and refracted rays make an angle of $90^{\circ}$ with each other . The angles of reflection and refraction are r and r' , the critical angle would be
cbse
class12
physics
ch-10
sec-b
additional
difficult
asked
Jun 20, 2016
by
meena.p
1
answer
The maximum no of possible interference maxima for slit separation equal to twice the wave length in Young's double slit experiment
cbse
class12
physics
ch-10
sec-a
additional
difficult
asked
Jun 20, 2016
by
meena.p
1
answer
One face of a prism is silvered and if refracting angle $30^{\circ}$ and refracting index 1.414 is silvered . At what angle must a ray of light fall on the silvered surface so that after refraction into prism and reflection at the silvered surface it retrace the path ?
cbse
class12
physics
ch-9
sec-b
ncert
difficult
asked
May 25, 2016
by
meena.p
1
answer
A thin convex lens of focal length 25 cm is cut into two pieces 0.5 cm above the principal axis . The top part is placed at $(0,0) $ and an object at $(-50 cm, 0)$. Find the coordinate axis ?
cbse
class12
physics
ch-9
sec-b
ncert
difficult
asked
May 25, 2016
by
meena.p
1
answer
At what angle should a ray of light be incident on the face of a prism of refracting angle $60^{circ}$ , So that it just suffers total internal reflection at the other face ? The refractive index of the prism is $1.524$
cbse
class12
physics
ch-9
ncert
difficult
sec-e
asked
May 17, 2016
by
meena.p
1
answer
An object 1.5 cm in placed on the side of the convex lens, where two lenses of focal lengths 30 cm and 20 cm are placed 8.0 cm apart with their principle axis coincident . The distance between the object and the convex lens is 40 cm. Determine the magnification produced by two lens system and size of the image
cbse
class12
physics
ch-9
ncert
difficult
sec-e
asked
May 17, 2016
by
meena.p
1
answer
Determined the effective focal length of the combination of two lenses of focal length 30 cm and 20 cm if they are placed 8.0 cm apart with their principal axes coincident. Does the answer depend on which side a beam a parallel light is incident ? Is the motion of effective focal length of system useful at all ?
cbse
class12
physics
ch-9
ncert
difficult
sec-e
asked
May 17, 2016
by
meena.p
1
answer
A placed bulb is placed at the bottom of a tank containing water to a depth of 80 cm. What is the area of the surface of water through which light from the bulb can emerge out ? Refractive index of water is 1.33 consider the bulb to be a point source .
cbse
class12
physics
ch-9
sec-b
ncert
difficult
asked
Feb 15, 2016
by
meena.p
1
answer
Find the magnitude of the magnetic field at the origin O due to a very long conductor carrying current I of the shape .
cbse
class12
physics
ch-4
sec-a
q86
ncert
difficult
asked
Aug 3, 2015
by
meena.p
1
answer
An electron and a positron are released $(0,0,0)$ and $(0,01.5 \;R)$ respectively , in a uniform magnetic field $\overrightarrow{B} =B_0 \hat i$, each with an equal momentum of magnitude $P= eBR$ Under what condition on the direction of momentum will the orbit be non- intersecting circles.
cbse
class12
physics
ch-4
sec-c
q78
ncert
difficult
asked
Jul 31, 2015
by
meena.p
1
answer
A rectangular conducting loop consists of two wires on two opposite sides of length l joined together by rod of length d. The wires are each of the same material but with cross - section differing by a factor of 2. The thicker wire has a resistance R and the rods of low resistance , Which in turn are connected to a constant voltage source $V_0$ the loop is placed in uniform magnetic field B at 45 to its plane . Find the $T$ the torque exerted by the magnetic field on the loop about an axis through the centers of rods.
cbse
class12
physics
ch-4
sec-c
q77
ncert
difficult
asked
Jul 31, 2015
by
meena.p
1
answer
A long straight wire carrying current of $25\;A$ rests on a table as shown in the figure. Another wire $PQ$ of length $1\;m$ mass $2.5\;g$ carries the same current but in the opposite direction. the wire $PQ$ is free opposite direction. The wire PQ is free to slide up and down . To what height will PQ rise ?
cbse
class12
physics
ch-4
sec-b
q75
ncert
difficult
asked
Jul 31, 2015
by
meena.p
1
answer
The cyclotron frequency $W= \large\frac{eB}{m}$ has correct dimension of $[T]^{-1}$. Is this statement true or false
cbse
class12
physics
ch-4
sec-a
q66
ncert
difficult
asked
Jul 30, 2015
by
meena.p
1
answer
A changed partice would continue to move with a constant velocity in a region where in ,
cbse
class12
physics
ch-4
sec-a
q65
ncert
difficult
asked
Jul 30, 2015
by
meena.p
1
answer
A cubical region of space is filled with some uniform electric and magnetic fields . An electron enters the cube magnetic fields. An electron enters the cube across one of its faces with velocity $\overrightarrow {v}$ and a position enters via opposite face with velocity - $\overrightarrow v$ At this instant .
cbse
class12
physics
ch-4
sec-a
q64
ncert
examplar
difficult
asked
Jul 30, 2015
by
meena.p
1
answer
Two identical current carrying coaxial loops carry current I in an opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C,
cbse
class12
physics
ch-4
sec-a
q63
ncert
difficult
asked
Jul 29, 2015
by
meena.p
1
answer
The gyro- magnetic ratio of an electron in an H- atom , according to Bohr model is
cbse
class12
physics
ch-4
sec-b
q61
ncert
difficult
asked
Jul 29, 2015
by
meena.p
1
answer
Biot -savart law indicates that the moving electrons (velocity $\overrightarrow{v}$) produce a magnetic field $\overrightarrow{B}$ such that
cbse
class12
physics
ch-4
sec-b
q56
ncert
difficult
asked
Jul 29, 2015
by
meena.p
1
answer
A uniform magnetic field of $1.5 \;T$ exists a cylindrical region $10.0 \;cm$ its direction parallel to the axis along east to west. A wire carrying current of $7.0 \;A$ in the north to south direction passes through this region . What is the magnitude and direction of the force on the wire if the wire is turned from N-S to north east -north west direction ?
cbse
class12
physics
ch-4
sec-b
q41
ncert
difficult
asked
Jul 28, 2015
by
meena.p
1
answer
A uniform magnetic field of $1.5 \;T$ exists a cylindrical region $10.0 \;cm$ its direction parallel to the axis along east to west. A wire carrying current of $7.0 \;A$ in the north to south direction passes through this region . What is the magnitude and direction of the force of the wire is the wire intended the axis ?
cbse
class12
physics
ch-4
sec-b
q40
ncert
difficult
asked
Jul 28, 2015
by
meena.p
1
answer
The wires which connected the battery of an automobile to its starting motor carrying a current of $300\;A$ (for a short time ). What is the force per unit length between the wires , if they are $70\;cm$long and $1.5 \;cm$ apart? Is the force attractive or repulsive ?
cbse
class12
physics
ch-4
sec-b
q39
ncert
difficult
asked
Jul 28, 2015
by
meena.p
1
answer
A straight horizontal conducting rod of length $0.45\;m$ and mass $60\;g$ is suspended by two vertical wires at its ends. A current of $5.0\;A$ is setup in the rod through the wires . What magnetic field should be setup normal to the conductor in order that the tension in the wires is zero?
cbse
class12
physics
ch-4
sec-b
q37
ncert
difficult
asked
Jul 28, 2015
by
meena.p
1
answer
A magnetic field using using Helmholtz coils is uniform in a small region and has a magnitude of $0.75\;T$ .In the same region a uniform electrostatic field is maintained in a direction normal to the common axis of the coils. A narrow beam of (single species) changed particles all accelerated through $15\;KV$ enters this region in a direction perpendicular to both the axis of the coils and the electrostatic field. If the beam remains undetected when the electro static field is $9 \times 10^{-5}V/m$ making a simple guess as to what the beam contains . Is the answer unique?
cbse
class12
physics
ch-4
sec-b
q36
ncert
difficult
asked
Jul 27, 2015
by
meena.p
1
answer
Two Concentric circular coils x and y of radii $16\;cm$ and $10\;cm$ respectively lie in the same vertical plane containing the north to south direction . coil x has 20 turns and carries a current of $16\;A$ coil y has 25 turns and carries a current of 18 A. The sense of the current in x is anticlock and clock wise in y, for an observe looks at the coils facing west. Find the magnitude and direction of the net magnetic force due to the coils at their center.
cbse
class12
physics
ch-4
sec-b
q25
ncert
difficult
asked
Jul 27, 2015
by
meena.p
1
answer
A magnetic field of $100\;G(1G= 10^{-4}\;T)$ is required which is uniform in a region of linear dimension about $10\;cm$ and area of cross section about $10^{-3}\;cm$ and the maximum current carrying capacity of a given coil of wire is $15\;A$ and the number of turns per unit length that can be round a core is at most $1000 turns/ m$ Same appropriate design particulars of a solenoid for the required purpose . Assume the core is not ferromagnetic .
cbse
class12
physics
ch-4
sec-b
q26
ncert
difficult
asked
Jul 24, 2015
by
meena.p
1
answer
Obtain the frequency of revolution of the electron in its circular orbit. Does the answer depends on the speed of the electron ? Explain
cbse
class12
physics
ch-4
sec-b
q22
ncert
difficult
asked
Jul 24, 2015
by
meena.p
1
answer
A closely ward solenoid $80\;cm$ long has $ 5$ layers of winding of 400 turns each.The diameter of the solenoid is $1.8 \;cm$ . If the current carried is $8.0\;A$ , estimate the magnitude of B inside the solenoid near its center .
cbse
class12
physics
ch-4
sec-b
q13
ncert
difficult
asked
Jul 23, 2015
by
meena.p
1
answer
A compass needle whose magnetic moment is $60Am^2$ pointing geographic north at a certain place, Where the horizontal component of earth's magnetic field is $40 \mu wbm^{-2}$ experiences a torque $1.2 \times 10^{-3}\;Nm$ What is the declination of the place?
cbse
class12
physics
ch-5
sec-a
q86
ncert
difficult
asked
Jul 21, 2015
by
meena.p
1
answer
The declination at a place is $20^{\circ}$ west. In what direction should a ship be stressed so that it reaches geographic north east ?
cbse
class12
physics
ch-5
sec-a
q85
ncert
difficult
asked
Jul 21, 2015
by
meena.p
1
answer
There are two current planer coils made each from identical wires of length L. $C_1$ is circular coil (radius R) and $C_2$ is square (side a). They are so constructed that they have same frequency of oscillation when they are placed in the same uniform magnetic field B and carry same current. Find a in term of R.
cbse
class12
physics
ch-5
sec-a
q59
ncert
difficult
asked
Jul 20, 2015
by
meena.p
1
answer
A bar magnet of magnetic m and moment of inertia I (about center , perpendicular to length ) is cut into two equal pieces, perpendicular to length . Let T be the period of oscillations of the original magnet about an axis . through the mid -point , perpendicular to length , in a magnetic field B. What would be the similar period $T^1$ for each piece?
cbse
class12
physics
ch-5
sec-a
q54
ncert
difficult
asked
Jul 16, 2015
by
meena.p
1
answer
A sample of paramagnetic salt contains $2.0 \times 10^{24} $ atomic dipoles each of dipole moment $1.5 \times 10^{-23}\; J/T$. the sample is placed under a homogeneous magnetic field of $0.64 \;T$ and colled to a temperature of $4.2 \;K$ . The degree of magnetic saturation achieved is equal to $15\%$ What is the total dipole moment of the sample for a magnetic field of $0.98 \;T$ and a temperature of $2.8 \;k$? (assume curies's law)
cbse
class12
physics
ch-5
sec-a
q51
ncert
difficult
asked
Jul 15, 2015
by
meena.p
1
answer
A magnetic dipole is under the influence of two magnetic fields. The angle between the field direction is $60^{\circ}$ and one of the field has a magnitude of $1.2 \times 10^{-2}\;T$ If the dipole comes to stable equilibrium to an angle of $15^{\circ}$ with this field , What is the magnitude of the other field ?
cbse
class12
physics
ch-5
sec-a
q49
ncert
difficult
asked
Jul 15, 2015
by
meena.p
1
answer
A telephone cable at a place has four long straight horizontal wires carrying a current of $1.0 \;A$ in the same direction east to west. The earth magnetic field at the place is $ 0.39 \;G$ and the angle of dip is $35^{\circ}$. The magnetic declination is nearly zero. what are the resultant magnetic fields at points $ 4.0 \;cm$ below the cable ?
cbse
class12
physics
ch-5
sec-a
q45
ncert
difficult
asked
Jul 15, 2015
by
meena.p
1
answer
A short bar magnet of magnetic moment $5.25 \times 10^{-2}\;J/T$ is placed with its axis perpendicular to the earth's field direction . At what distance from the center of the magnet , the resultant field is inclined at $45^{\circ}$ with earth's field on its normal bisector. Magnitude of the earth's field at the place is given to be $0.42\;G$ Ignore the length of the magnet in companion to the distance involved
cbse
class12
physics
ch-5
sec-b
q31
ncert
difficult
asked
Jul 14, 2015
by
meena.p
1
answer
A short bar magnet placed in a horizontal plane has its axis aligned along the magnet north - south direction . Null points are found on the axis of the of the magnet at $14\;cm$ from the center of the magnet . The earth magnetic field at the place is $0.36\;G$ and the cycle of dip is zero. If the bar magnet is turned around by $180^{\circ}$Where will the new null points be located ?
cbse
class12
physics
ch-5
sec-a
q30
ncert
difficult
asked
Jul 13, 2015
by
meena.p
1
answer
Determine the current though the battery of internal resistance $0.5 \Omega$ for the circuit as shown in the figure. How much power is distributed in $6 \Omega$ resistance ?
cbse
class12
physics
ch-3
sec-b
q96
difficult
asked
Jul 8, 2015
by
meena.p
1
answer
The rate of reaction for A---> products is 10 mol.lit-1.min-1 at time t1=5minutes. what will be the rate at the time t2=10minutes
cbse
class12
jeemain
physical-chemistry
difficult
ch3
kinetics
chemical
asked
Jul 7, 2015
by
excellentdeals18
1
answer
Consider circuit in the given figure. How much energy is absorbed by electron from the initial state of no current (ignore thermal motion ) to the state of drift velocity ?
cbse
class12
physics
ch-3
sec-b
q91
difficult
asked
Jul 7, 2015
by
meena.p
1
answer
Determine the current drawn from a 12 v supply with internal resistance $0.5 \Omega$ by the infinite network shown in the figure . Each resistor has $\Omega$ resistance
cbse
class12
physics
ch-3
sec-c
q89
difficult
asked
Jul 7, 2015
by
meena.p
1
answer
Draw V-I graph for ohmic and non- ohmic materials give one example each
cbse
class12
physics
ch-3
sec-a
q62
difficult
asked
Jul 6, 2015
by
meena.p
1
answer
When the galvanometer shows no deflection , what will be the current flowing through the $5 \Omega$ resistance ?
cbse
class12
physics
ch-3
sec-a
q49
difficult
asked
Jul 6, 2015
by
meena.p
2
answers
Two wires of equal lengths , One of aluminium and the other of copper have the same resistance . Which of the two wires is lighter. $[\rho_A =2.63 \times 10^{-8} \Omega m, \rho_{cn}= 1.72 \times 10^{-8} \Omega -m$. Relative density of $Al =2.7$ , Relative density of $Cu= 8.9 ]$
cbse
class12
physics
ch-3
sec-a
q71
difficult
asked
Jul 2, 2015
by
meena.p
1
answer
The number of density of free electron in a copper conductor estimated at $8.5 \times 10^{20}m^{-3}$. How long does an electron take a drift from one end of a wire $3.0 \; m$ long to its other end ? The area of cross - section of the wire is $2 \times 10^{-6}\;m^2$ and it is carrying of $3.0 \;A$
cbse
class12
physics
ch-3
sec-b
q66
difficult
asked
Jul 1, 2015
by
meena.p
1
answer
In a metre bridge , the balance point is found to be at $39.5\;cm$ from the end A, when the resistor Y is of $12.5 \;ohm$. Determine the resistance of x. Why are the connections between resistors in a metre bridge made of thick copper ships ? What happens if the galvanometer and cell are interchanged at the balanced point of the bridge ? would the galvanometer show any current?
cbse
class12
physics
ch-3
sec-b
q64
difficult
asked
Jul 1, 2015
by
meena.p
1
answer
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