A closely wounded circular coil of radius 5 cm produces a magnetic field of at its center. The current through the coil is _________A.
[Given, number of turns in the coil is 100 and ]

Official solved question paper for Joint Entrance Examination (Main). Review all 90 questions, official answer keys, and detailed step-by-step solutions below, or attempt online with timer and negative marking.
A closely wounded circular coil of radius 5 cm produces a magnetic field of at its center. The current through the coil is _________A.
[Given, number of turns in the coil is 100 and ]
Given below are two statements.
Statement I : Electric potential is constant within and at the surface of each conductor.
Statement II : Electric field just outside a charged conductor is perpendicular to the surface of the conductor at every point.
In the light of the above statements, choose the most appropriate answer from the options given below.
A ball is projected with kinetic energy E, at an angle of to the horizontal. The kinetic energy of this ball at the highest point of its flight will become :
Two light beams of intensities 4I and 9I interfere on a screen. The phase difference between these beams on the screen at point A is zero and at point B is . The difference of resultant intensities, at the point A and B, will be _________ I.
If the length of a wire is made double and radius is halved of its respective values. Then, the Young's modulus of the material of the wire will :
A travelling microscope has 20 divisions per on the main scale while its vernier scale has total 50 divisions and 25 vernier scale divisions are equal to 24 main scale divisions, what is the least count of the travelling microscope?
A wire of length carrying current of is bent to form a circle. The magnetic moment of the coil is ________ A . [Given ]
The pressure and density of diatomic gas changes suddenly to and respectively during an adiabatic process. The temperature of the gas increases and becomes ________ times of its initial temperature. (given )
One mole of a monoatomic gas is mixed with three moles of a diatomic gas. The molecular specific heat of mixture at constant volume is ; then the value of will be _________. (Assume that the given diatomic gas has no vibrational mode).
Find the modulation index of an AM wave having variation where maximum amplitude of the AM wave is .
Given below are two statements : One is labelled as Assertion (A) and other is labelled as Reason (R).
Assertion (A) : Time period of oscillation of a liquid drop depends on surface tension (S), if density of the liquid is and radius of the drop is r, then is dimensionally correct, where K is dimensionless.
Reason (R) : Using dimensional analysis we get R.H.S. having different dimension than that of time period.
In the light of above statements, choose the correct answer from the options given below.
A coil of inductance 1 H and resistance is connected to a battery of 6 V. Determine approximately :
(a) The time elapsed before the current acquires half of its steady - state value.
(b) The energy stored in the magnetic field associated with the coil at an instant 15 ms after the circuit is switched on. (Given )
The X-Y plane be taken as the boundary between two transparent media and . in has a refractive index of and with has a refractive index of . A ray of light travelling in along the direction given by the vector , is incident on the plane of separation. The value of difference between the angle of incident in and the angle of refraction in will be __________ degree.
Match List - I with List - II :
| List - I | List - II | ||
|---|---|---|---|
| (a) | UV rays | (i) | Diagnostic tool in medicine |
| (b) | X-rays | (ii) | Water purification |
| (c) | Microwave | (iii) | Communication, Radar |
| (d) | Infrared wave | (iv) | Improving visibility in foggy days |
Choose the correct answer from the options given below :
Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first permitted level.
In an experiment to find out the diameter of wire using screw gauge, the following observations were noted :

(A) Screw moves on main scale in one complete rotation
(B) Total divisions on circular scale
(C) Main scale reading is
(D) division of circular scale is in the pitch line
(E) Instrument has 0.03 mm negative error
Then the diameter of wire is :
If , then is :
The kinetic energy of emitted electron is E when the light incident on the metal has wavelength . To double the kinetic energy, the incident light must have wavelength:
If the potential barrier across a p-n junction is . Then the electric field intensity, in the depletion region having the width of , will be __________ .
Two bodies of mass and have position vectors and respectively. The magnitude of position vector of centre of mass of this system will be similar to the magnitude of vector :
Two metallic wires of identical dimensions are connected in series. If and are the conductivities of the these wires respectively, the effective conductivity of the combination is :
A spherically symmetric charge distribution is considered with charge density varying as
Where, is the distance from the centre O (as shown in figure). The electric field at point P will be:

The time period of oscillation of a simple pendulum of length L suspended from the roof of a vehicle, which moves without friction down an inclined plane of inclination , is given by :
A ball is thrown up vertically with a certain velocity so that, it reaches a maximum height h. Find the ratio of the times in which it is at height while going up and coming down respectively.
An object is projected in the air with initial velocity u at an angle . The projectile motion is such that the horizontal range R, is maximum. Another object is projected in the air with a horizontal range half of the range of first object. The initial velocity remains same in both the case. The value of the angle of projection, at which the second object is projected, will be _________ degree.
Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Clothes containing oil or grease stains cannot be cleaned by water wash.
Reason (R): Because the angle of contact between the oil/grease and water is obtuse.
In the light of the above statements, choose the correct answer from the option given below.
A smooth circular groove has a smooth vertical wall as shown in figure. A block of mass m moves against the wall with a speed v. Which of the following curve represents the correct relation between the normal reaction on the block by the wall (N) and speed of the block (v) ?





If the acceleration due to gravity experienced by a point mass at a height h above the surface of earth is same as that of the acceleration due to gravity at a depth from the earth surface. The value of will be _________.
(use
The current I flowing through the given circuit will be __________A.

An alternating emf is applied to a circuit containing an inductance of . If an a.c. ammeter is connected in the circuit, its reading will be :
The reaction between X and Y is first order with respect to X and zero order with respect to Y.
| Experiment | |||
|---|---|---|---|
| I | 0.1 | 0.1 | |
| I | L | 0.2 | |
| III | 0.4 | 0.4 | |
| IV | 0.1 | 0.2 |
Examine the data of table and calculate ratio of numerical values of M and L. (Nearest Integer)
Which among the following pairs of the structures will give different products on ozonolysis? (Consider the double bonds in the structures are rigid and not delocalized.)




When 600 mL of 0.2 M HNO3 is mixed with of 0.1 M NaOH solution in a flask, the rise in temperature of the flask is ___________ .
(Enthalpy of neutralisation and Specific heat of water ) (Neglect heat capacity of flask)
Which among the following pairs has only herbicides?
Which among the following is the strongest Bronsted base?




should be an inner orbital complex. Ignoring the pairing energy, the value of crystal field stabilization energy for this complex is ____________ . (Nearest integer)
The minimum uncertainty in the speed of an electron in an one dimensional region of length (Where Bohr radius ) is _________ .
(Given : Mass of electron = 9.1 1031 kg, Planck's constant h = 6.63 1034 Js)

Consider the above reaction sequence, the Product 'C' is :




If the solubility product of PbS is 8 1028, then the solubility of PbS in pure water at 298 K is x 1016 mol L1. The value of x is __________. (Nearest Integer)
[Given : = 1.41]

Which among the following represent reagent 'A'?




of solution of in water was prepared in beaker. Albumin from the egg was poured into solution and stirred well. This resulted in a/an :
The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives :
Which of the following compounds is an example of hypnotic drug?
Lithium nitrate and sodium nitrate, when heated separately, respectively, give :
If gas is bubbled through water at , the number of millimoles of gas that dissolve in 1 litre of water is __________. (Nearest Integer)
(Given : Henry's Law constant for at is bar and partial pressure of bar)
(Assume solubility of in water is too small, nearly negligible)
In neutral or faintly alkaline medium, being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be :
In metallurgy the term "gangue" is used for :
Which of the following pair of molecules contain odd electron molecule and an expanded octet molecule?
Resistance of a conductivity cell (cell constant ) filled with solution of is (labelled as solution 1). When the same cell is filled with solution of , the resistance is (labelled as solution 2). The ratio of molar conductivity of solution 1 and solution 2 is i.e. . The value of is __________. (Nearest integer)
Given, molar mass of is .
In following pairs, the one in which both transition metal ions are colourless is :
In a linear tetrapeptide (Constituted with different amino acids), (number of amino acids) (number of peptide bonds) is ________.
A compound 'X' is acidic and it is soluble in NaOH solution, but insoluble in NaHCO3 solution. Compound 'X' also gives violet colour with neutral FeCl3 solution. The compound 'X' is :




Consider the following reaction sequence:

The product 'B' is :





Consider the above reaction, the compound 'A' is :




Number of lone pairs of electrons in the central atom of and , respectively, are :
The first ionization enthalpy of Na, Mg and Si, respectively, are : 496, 737 and . The first ionization enthalpy () of is :
Consider the above reaction, the limiting reagent of the reaction and number of moles of formed respectively are :

Considering the above reactions, the compound 'A' and compound 'B' respectively are :




In bromination of Propyne, with Bromine, 1, 1, 2, 2-tetrabromopropane is obtained in 27% yield. The amount of 1, 1, 2, 2-tetrabromopropane obtained from 1 g of Bromine in this reaction is ___________ 101 g. (Nearest integer)
(Molar Mass : Bromine = 80 g/mol)
Ionic radii of cation and anion are 102 and respectively. These ions are allowed to crystallize into an ionic solid. This crystal has cubic close packing for . is present in all octahedral voids. The edge length of the unit cell of the crystal AB is __________ pm. (Nearest Integer)
If , then is equal to :
Let be an A.P. If , then is equal to _________.
Let A and B be two non-zero real matrices such that AB is a zero matrix. Then
If the foot of the perpendicular from the point on the plane , is , then the distance of the point A from the plane P, measured parallel to a line with direction ratios , is equal to :
Let and . Let be a vector satisfying . If and are non-parallel, then the value of is :
Let and . If , then the sum of all the elements in the set is equal to __________.
Let the circumcentre of a triangle with vertices A(a, 3), B(b, 5) and C(a, b), ab > 0 be P(1,1). If the line AP intersects the line BC at the point Q, then is equal to :
If , then the maximum value of is :
Let R be a relation from the set to itself such that , where are prime numbers}. Then, the number of elements in R is :
Let and be two unit vectors such that the angle between them is . If is the angle between the vectors and , then the value of is equal to :
The area of the region
is equal to :
Let the mirror image of a circle in line be . If is the radius of circle , then is equal to ________.
Let . Then which of the following statements are true?
is a point of local minima of
is a point of inflection of
is increasing for
The number of points, where the function ,
, is NOT differentiable, is :
Let the solution curve of the differential equation pass through the point . Then, is equal to :
If , then is equal to :
Let a line L pass through the point of intersection of the lines and . If the line also passes through the point and touches the circle , then the eccentricity of the ellipse is :
Let . Then, the sum of roots of all the equations , is __________.
Let a line with direction ratios be perpendicular to the lines with direction ratios and . If the point of intersection of the line and the plane is , then is equal to _________.
Let p and p + 2 be prime numbers and let
Then the sum of the maximum values of and , such that and divide , is __________.
If , then 34 k is equal to _________.
Let the focal chord of the parabola along the line meet the parabola at the points M and N. Let the line L be a tangent to the hyperbola . If O is the vertex of P and F is the focus of H on the positive x-axis, then the area of the quadrilateral OMFN is :
Let the ratio of the fifth term from the beginning to the fifth term from the end in the binomial expansion of , in the increasing powers of be . If the sixth term from the beginning is , then is equal to _________.
The angle of elevation of the top of a tower from a point A due north of it is and from a point B at a distance of 9 units due west of A is . If the distance of the point B from the tower is 15 units, then is equal to :
The integral is equal to :
Let the mean and the variance of 20 observations be 15 and 9 , respectively. For , if the mean of is 178 , then the square of the maximum value of is equal to ________.
Let . Then the probability, that a randomly chosen number n from the set S such that , is :
The statement is equivalent to :
If , where , then which of the following is NOT correct?
The number of matrices of order , whose entries are either 0 or 1 and the sum of all the entries is a prime number, is __________.