MM Home Tuition - CBSE Class 12 Physics 2026 Question and Solution

A wire is gradually stretched to make it 100% longer , its resistance will increase by :
100% b) 200% c) 300% d) 400%
A closely wound long solenoid of self inductance L is cut in to two identical solenoid . The value of self inductance of each small solenoid will be : a) L/2 b)2L c)3L d) 4L
Which of the following characteristics of electron determine current in conductor ? a)Drift velocity only b) Thermal velocity only c) both drift velocity and thermal velocity d) neither drift nor thermal velocity
Two particles of masses m1 and m2 having charges q1 and q2 respectively are projected with the same velocity in a region of uniform magnetic field vertically upward. If they describe circular paths as shown in figure , one may conclude that
Paschen series in spectrum of Hydrogen atom lies in : a) infrared region b) ultraviolet region c) visible region d) partly in ultraviolet region and partly in visible region
The kinetic energy of a charged particle is increased to four times of its initial value . The de Broglie wavelength associated with the particle will a) increase by 100% of its initial value b) increase by 50 % of its initial value c)decrease by 25% of its initial value d) decrease by 50% of its initial value
In a reversed-biased p-n junction diode the applied voltage mostly drops across a) p-region only b) n-region only c) depletion region d) the diode
A coil having 100 closely wound turns and area of cross-section 300mm2 carries a current of 5mA . The magnitude of magnetic moment associated with the coil is a) 6*10 -4 Am2 b) 3*10-5 Am2 c) 1.5 * 10 -4 Am2 d) 5*10 -5 Am2
An ac voltage is given as v= 14 sin (314t) v . The average and the effective value of the voltage (in v) over a cycle are respectively : a) 14 and 7 b) 10 and 14 c) 0 and 10 d) 10 and 0
The ratio of amplitude of electric field to the amplitude of magnetic field associated with an electromagnetic wave propagating in glass (n=1.5) is A) 3* 10 8 m/s B) 2* 10 8 m/s c) 3.3 * 10 -9 m/s D ) 5* 10 -9 m/s
Radiation of wavelength 331nm irradiates the following metals : Which of the following statement is correct ? a) only Na and K show photoelectric emission b) Only Mo will not show photoelectric emission c) all of the given metals show photoelectric emission d) None of them show photoelectric emission
In an experiment on photoelectric emission , the intensity of incident radiation is halved keeping its frequency constant , as a result a) cut-off potential will increase b) maximum kinetic energy of photoelectrons will remain the same c) photocurrent will increase d) cut-off potential will decrease
Assertion (A): the conductivity of an n-type semiconductor is higher than that of a p-type semiconductor at a given temp Reason (R): The electrons being in the conduction band in n-type semiconductor are more mobile than the holes in the valence band in p-type semiconductor .
Assertion(A): The work done in taking a unit positive charge around a closed loop of an electric circuit involving cells and resistors in the loop is zero .Reason(R) : the potential at appoint depends on the location of the point in the loop . after completing one round the charge comes back to the point of start.
Assertion(A) : when a ferromagnetic substance is heated to high temperature it becomes paramagnetic in nature . Reason(R): The disappearance of magnetization of a ferromagnet is abrupt and not gradual .
Assertion(A): when a convex lens made of glass is immersed in water its converging power increases . Reason(R): The focal length of a lens depends only on the radii of curvature of its two faces .
(a) state Huygens principle . How did Huygens justify the absence of the backwave on a spherical wavefront ? or b) In a single-slit diffraction experiment light of wavelength ƛ illuminates the slit of width a . The diffraction patteren is observed on a screen kept at a distance D from the slits .(i) Depict variation of intensity in the fringe patteren with the angular position of the fringes .(ii) How is the linear width of central maximum affected when separation between the slit and the screen is decreased ?
The hole concentration in an intrinsic semiconductor is 5* 10⁸ m-3 . when it is dp[ed with certain impurity the electron concentration becomes 4* 10 12 m-3 . find the new value of the hole concentration . also identify the type of new semiconductor formed after doping ?
A concave mirror of radius of curvature 16cm produces two-times enlarged image of an object kept infront of it . Find the position of the object .
Prove that the density of nuclear matter is same for all nuclei .
An electric dipole consistes of two point charges 1μc and -1μc , held 10cm apart . it is subjected to a uniform electric field of 100N/c . calculate the amount of workdone in turning the dipole from its position of stable equilibrium to the position of unstable equilibrium in the field .
(a) The figure given below shows three straight long parallel conductors ,2,3 kept in x-y plane , carrying current 2I ,I,3I respectively as shown in figure . find the magnitude and direction of (i) net magnetic field at a point on conductor 1 (ii) net magnetic force acting on unit length of conductor 1 due to conductor 2 and 3 . or (b) A rectangular loop of sides l and b and resistrtors R is kept in a region in which the magnetic field varies as B= B0 sin wt (I) Derive expression for the emf induced in the loop . (ii) Find the effective value of current that flows in the loop
With the help of circuit diagram explain the working of a full wave rectifier , depict the input and output waveform .
In Bohr model of hydrogen atom calculate a) the radius of innermost electron orbit b) the spped of electron in this orbit
A) Explain how the dual aspect of matter is evident in the de Broglie relation . (b) Radiation of wavelength ƛ is incident on a photosensitive surface . Find the DeBroglie wavelength of electron emitted from the surface .Assume that the work function of the surface is negligible .
What are microwaves ? How are they produced ? Give any two uses of microwaves ?
A conducting rectangu8lar loop of area 5 cm2 and resistance 4Ω is removed from a region of uniform magnetic field , acting normal to the plane of the loop . The value of induced current I in the loop varies time t , as shown in figure . find (a) total charge that passed through the loop b) change in magnetic flux through the loop c) magnitude of magnetic flux in the region .
A) The two kirchoff’s rules are based on law of conservation of two physical quantities . name the quantities ? B) frind magnitude and direction of current in 1Ω resistors in the given circuit ?
An astronomical telescope consists of two converging lenses . one of them of large aperature and large focal lenghth is called objective lens and the other one of smaller focal length and smaller aperature is called the eyepiece . it is used to see distsnt objects which are not seen clearly with naked eyes . the image formed by the objective lens nacts as an objects for the eyepiece and the final image produced by the eyepiece is magnified . (I) the image formed by the objective lens and eye piece are respectively : a) virtual.real b) real , virtual c) virtual ,virtual d) real,real (ii) the magnification produced by the trelescope does not depends upon the (a) colour of light b) focal length of objective lens c) focal length of eye piece d) aperature of objective lens and eye piece (iii) which of the following statement is not correct for this telescope ? (a) the focal length of objective lens (f0) is larger than the focal length of eye piece (fe). B) its magnifying power can be increased by increasing the focal lengtyh of objective lens (f0) c) The distance between two lenses is more than (fo+fe) (iv) the magnifying power can be increased by increasing the focal length of eye piece (iv )(a) an astronomical relescope telescope has objective lens and eye piece of focal length 80cm and 4 cm respectively . to view the image in normal adjustment , the lenses must be separated by a distance of a) 84cm b)76cm c) 20cm d) 320cm or b) consider the telescope described in question (iv)(a) its magnifying power in normal adjustment will be : a) 320 b) 84 c) 76 d) 20
A student sets up the circuit as shown in the figure to find the value of unknown resistance resistance x and records a set of reading of the voltmeter and the ammeter by using the rheostat . (I) if resistor X were made of manganin and readings for v and I are taken with out switching off the circuit , the graph between V and I will be as : (ii) Error in the value of X obtained from different sets of voltmeter and ammeter readings is (A) due to error in voltmeter reading only B) due to error in ammeter reading only C) equal to the sum of error in voltmeter reading and error in ammeter reading . d) equal to error in voltmeter reading divided by the error in ammeter reading . (iii) if the movable end of rheostat is moved towards p then a) reading in ammeter decreases and reading in voltmeter increases b) readings in both voltmeter and ammeter increases c) reading in ammeter increases and redaing in voltmeter decreases d) readings in both voltmeter and ammeter decreases (iv) (a) suppose the unknown resistance X is replaced by a wire made of same metal . this wire consists of three parts , of the same lenghth L but has radii r,r/3,r/2 as shown in figure , for a particular setting of the rheostat let v1,v2,v3 be the value of drift velocities in parts AC,CD,DB . then a) v1>v2>v3 b)v2>v3>v1 c) v3>v2>v1 d) v1=v2=v3 or b) consider the same wire as shown in figure in question (iv)(a) connected in place of x . for a particular setting of rheostat let E1,E2,E3 be the value of electric field in part AC,CD and DB . Then a) E1 = E2 = E3 b) E3> E2> E1 c) E2>E3>E1 d) E1> E2> E3
A) (i) explain the following statements giving reason a) An equipotential surface through a point is normal to the electric field at that point b) when a dielectric is placed in an external electric field the electric field inside the dielectric is less than that outside it. C) The potential difference between the plates of a charged parallel plate capacitor decreses when its plates are brought closer . (ii) obtain an expression for the workdone to dissociate the system of three charges q,-4q,2q placed at the vertices A<B<C respectively of an equilateral triangle of side a . or b(i) Answer the following giving reason (I) The electron drift speed is estimated to be only a few mm/s for currents in the range of few amperes . how then is the current established almost the instant a circuit is closed ?(II)A low voltage supply from which one needs high currents must have very low internal resistance why ?(III) The assertion that V=IR is a statement of ohm’s law is not true . why?
(A)(i) define refractive index of medium in terms of speed of light ?

(ii) Derive the relation for the refractive index (μ) of a prism in terms of angle of minimum deviation (dm) and angle of prism (A) .

(iii) A ray of light qp is incident normally on face BC of a triangular prism ABC of refractive index 1.5 kept in air , as shown in figure . Trace the path of the ray as it passes through the prism and give relevant explanation . OR B(i)what is the difference between a ray and a wavefront ?

(ii) A plane wave is incident on a reflecting surface . using Huygens principle show how it is reflected from the surface . Hence verify laws of reflection .

(iii) depict refraction of a plane wave by a conves lens .

33)(A)(i)Define the terms(I) resonant frequency and (II) power factor of a series LCR circuit . For what value of the power factor will the power dissipated in the circuit be maximum ? (ii) An inductor of 5/π H , capacitor of 50/π μF and a resistor of 400 Ω are connected in series across an ac voltage v= 140 sin (100πt) calculate (i) impedance of the circuit (ii rms value of current that flows in the circuit (√2 = 1.414))

(b)(i)Draw a labeled diagram of a step-up transformer . obtain the ratio of secondary voltage to primary voltage In terms of number of turns in the two coils .

(ii) The number of turns in the primary and seconday coil of an ideal transformer are 100 and 5000 respectively . if 3.3kW power is supplied to the transformer at 220 V . find the (i) current in the primary coil (ii) output voltage