Recent questions in JEEMAIN and NEET

The de-Broglie wavelength of an electron having $80\;eV$ energy is nearly : ( $1\;eV = 1.6 \times 10^{-19} J$ ) Mass of electron = $9 \times 10^{-31} kg$ Planck's constant = $6.6 \times 10^{-34} Js$ )

asked Dec 11, 2018 by pady_1

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Photoelectric emission is observed from a metallic surface for frequencies $v_1$ and $v_2$ of the incident light rays $(v_1 > v_2)$ . If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of $1 : k$ , then the threshold frequency of the metallic surface is :

asked Dec 11, 2018 by pady_1

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A particle of mass $0.6 \;g$ and having charge of $25\;nC$ is moving horizontally with a uniform velocity $1.2 \times 10^4 \; ms^{-1}$ in a uniform magnetic field, then value of the magnetic induction is : $(g =10\; ms^{-2} )$

asked Dec 11, 2018 by pady_1

0 answers

If a change in current of $0.01 \;A$ in one coil produces a change in magnetic flux of $2 \times10^{-2} Wb$ in the other coil, then the mutual inductance of the two coils in henry is :

asked Dec 11, 2018 by pady_1

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A wire in the form of a square of side $'a'$ carries a current $'i'$ . Then the magnetic induction at the centre of the square is : (Magnetic permeability of free space = $\mu_0$ )

asked Dec 11, 2018 by pady_1

0 answers

Thomson coefficient of a conductor is $10\; \mu\; VK$ . The two ends of it are kept at $50^{\circ}C$ and $60^{\circ}C$ respectively. Amount of heat absorbed by the conductor when a charge of $10\; C$ flows through it, is :

asked Dec 11, 2018 by pady_1

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When a resistor of $11 \; \Omega$ is connected in series with an electric cell, the current flowing in it is $0.5 \;A$ . Instead, when a resistor of $5 \Omega$ is connected to the same electric cell in series, the current increases by $0.4 \;A$ . The internal resistance of the cell is :

asked Dec 11, 2018 by pady_1

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A closed hollow insulated cylinder is filled with gas at $0^{\circ}C$ and also contain an insulated piston of negligible weight and negligible thickness at the middle point. The gas in one side of the piston is heated to $100^{\circ}C$ . If the piston moves $5\; cm$ . The length of the hollow cylinder is :

asked Dec 11, 2018 by pady_1

0 answers

When an air bubble of radius $'r'$ rises from the bottom to the surface of a lake. Its radius becomes $\frac{5r}{4}$ (the pressure of the atmosphere is equal to the 10 m height to water column). If the temperature is contant and the surface tension is neglected the depth of the lake is :

asked Dec 11, 2018 by pady_1

0 answers

A lead bullet of mass $10\; g$ travelling at $300\; m/s$ strikes against a block of wood and comes to rest. Assuming $50 \%$ of heat is absorbed by the bullet, the increase in its temperature is : (specific heat of lead = $150 \; J/kg ^{\circ} C$ )

asked Dec 11, 2018 by pady_1

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The pressure and density of a diatomic gas $(\gamma = \frac{7}{5} )$ changes adiabatically from $(P, d)$ to $(P', d')$ . If $\frac{d'}{d} =32$ . Then $\frac{P'}{P}$ is :

asked Dec 11, 2018 by pady_1

0 answers

The wavelength of maximum intensity of radiation emitted by a star is $289.8\;nm$ . The radiation intensity of the star is : (Stefan's contant = $5.67 \times 10^{-8} \;Wm^2K^{-4}$ , constant $b = 2898\; \mu m K$ )

asked Dec 11, 2018 by pady_1

0 answers

In order to double the frequency of the fundamental note emitted by a stretched string, the length is reduced to $\frac{3}{4}^{th}$ of the original length and the tension is changed. The factor by which the tension is to be changed is :

asked Dec 11, 2018 by pady_1

1 answer

The sound waves of wavelengths 5 m and 6 m formed 30 beats in 3 seconds. The velocity of sound is :

asked Dec 11, 2018 by pady_1

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In the visible region the dispersive powers and the mean angular deviations for crown and flint glass prisms are $\omega,\; \omega'$ and $d, \; d'$ respectively. The condition of getting dispersion wih zero deviation, when the two prisms are combined is :

asked Dec 11, 2018 by pady_1

0 answers

One face of the glass prism is silver polished. A light ray falls at an angle of $45^{\circ}$ on the other face. After reflection it is subsequently reflected from the silvered face and then retraces its path. The refracting angle of prism is $30^{\circ}$ . The refractive index of the prism is :

asked Dec 11, 2018 by pady_1

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When a glass prism of refracting angle $60^{\circ}$ is immersed in a liquid its angle of minimum deviation is $30^{\circ}$ . The critical angle of glass with respect to the liquid medium is :

asked Dec 11, 2018 by pady_1

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Light waves producing interference have their amplitudes in the ratio $3:2$ . The intensity ratio of maximum and minimum of interference fringes is :

asked Dec 11, 2018 by pady_1

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The difference in the number of wavelengths, when yellow light propagates through air and vacuum columns of the same thickness, is one. The thickness of the air column is : Refractive index of air $\mu_c = 1.0003$ Wavelength of yellow light in vacuum = $6000 \; \mathring{A}$

asked Dec 11, 2018 by pady_1

0 answers

A magnet of length $10\; cm$ and magnetic moment $1\; Am^2$ is placed along side AB of an equilateral triangle ABC. If the length of the side AB is $10\; cm$ . The magnetic induction at the point 'C' is : $(\mu_0 = 4 \pi \times 10^{-7} Hm^{-1})$

asked Dec 11, 2018 by pady_1

1 answer

A magnet freely suspended in a vibration magnetometer makes $40$ oscillations per minute at place 'A' and $20$ oscillations per minute at a place 'B'. If the horizontal component of earth's maagnetic field at 'A' is $36 \times 10^{-6}T$ , then its value at 'B' is :

asked Dec 11, 2018 by pady_1

0 answers

A body of capacity $4 \; \mu F$ is charged to $80\;V$ and another body of capacity $6 \; \mu F$ is charged to $30\;V$ . When thet are connected the energy lost by $4 \; \mu F$ capacitor is :

asked Dec 11, 2018 by pady_1

0 answers

There is a uniform electric field of strength $10^3\; V\;m^{-1}$ along $y$ -axis. A body of mass $1\; g$ and charge $10^{-6}C$ is projected into the field from origin along the positive $X$ -axis with a velocity $10\; ms^{-1}$ . Its speed in $ms^{-1}$ after $10\; sec$ is : (Neglect gravitation)

asked Dec 11, 2018 by pady_1

0 answers

A $20\; F$ capacitor is charged to $5\; V$ and isolated. It is then connected in parallel with an uncharged $30\;F$ capacitor. The decrease in the energy of the system will be :

asked Dec 11, 2018 by pady_1

0 answers

Two electric charges of $9\; \mu C$ and $- 3 \; \mu C$ are placed $0.16\;m$ apart in air. There will be a point $'P'$ at which electric potential is zero on the line joining two charges and in between them. The distance of $P$ from $9 \; \mu\;C$ is :

asked Dec 11, 2018 by pady_1

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If the charge on a body is increased by 2 $C$ , the energy stored in it increases by $21 \%$ . The original charge on the body in coulomb is :

asked Dec 11, 2018 by pady_1

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A nichrome wire $50\; cm$ long and $1 \; mm^2$ cross-section carries a current of $4\;A$ . When connected to $2$ volt battery. The resistivity of nichrome with in $\Omega^{-m}$ is :

asked Dec 11, 2018 by pady_1

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The number of real roots of $3^{2x^2 - 7x + 7} =9$ is :

asked Dec 11, 2018 by pady_1

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If $|x| < 1$ , then the coefficient of $x^n$ in expansion of $(1 + x + x^2 + x^3 + ...)^2$ is :

asked Dec 11, 2018 by pady_1

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The coefficient of $x^5$ in $(1 + 2x + 3x^2 + ....)^{-3/2}$ is :

asked Dec 11, 2018 by pady_1

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$e^{(x-1) - \frac{1}{2} (x-1)^2 + \frac{(x-1)^3}{3} - \frac{(x-1)^4}{4} + . . . }$ equal to :

asked Dec 11, 2018 by pady_1

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$\displaystyle \lim_{n = 0}^{\infty} \frac{(\log_e x)^n}{n!}$ is equal to

asked Dec 11, 2018 by pady_1

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$\tan^{-1} (\frac{1}{4}) + \tan^{-1} (\frac{2}{9})$ is equal to :

asked Dec 11, 2018 by pady_1

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If $\alpha$ is a root of $25 \cos^2 \theta + 5 \cos \theta - 12 =0$ $\frac{\pi}{2} < \alpha < \pi$ , then $\sin 2 \alpha$ is equal to :

asked Dec 11, 2018 by pady_1

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The equation $a \sin x + b \cos x = c$ where $|c| > \sqrt{a^2 + b^2}$ has :

asked Dec 11, 2018 by pady_1

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In a $\Delta ABC$ , $\tan \frac{A}{2} = \frac{5}{6}, \; \tan \frac{C}{2} = \frac{2}{5}$ , then :

asked Dec 11, 2018 by pady_1

1 answer

In a triangle $ABC, \; a = 4, \; b = 3, \; \angle{A} = 60^{\circ}$ , then $c$ is the root of the equation :

asked Dec 11, 2018 by pady_1

0 answers

If $y = \sin^2 \theta + \mathrm{cosec}^2 \theta, \; \theta \neq 0$ , then :

asked Dec 11, 2018 by pady_1

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If $\sin (\alpha + \beta) = 1$ , $\sin (\alpha- \beta) = \frac{1}{2}$ , then $\tan (\alpha + 2\beta) \tan (2 \alpha +\beta)$ is equal to :

asked Dec 11, 2018 by pady_1

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If $\tan \theta = -\frac{4}{3}$ , then $\sin \theta$ is :

asked Dec 11, 2018 by pady_1

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The value of $\frac{1 - \tan^2 15^{\circ}}{1+ \tan^2 15^{\circ}}$ is :

asked Dec 11, 2018 by pady_1

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The centre of the circle given by $\overrightarrow{r}.(\hat{i} + 2 \hat{j} + 2 \hat{k}) =15$ and $| \overrightarrow{r} - (\hat{j} + 2 \hat{k})| = 4$ is :

asked Dec 11, 2018 by pady_1

0 answers

If the vectors $\overrightarrow{a} = x \hat{i} + y \hat{j} + z \hat{k}$ and such that $\overrightarrow{a} , \; \overrightarrow{c}$ and $\overrightarrow{b}$ form a right handed system, then $\overrightarrow{c}$ is :

asked Dec 11, 2018 by pady_1

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The equation of the chord joining two points $(x_1, y_1)$ and $(x_2, y_2)$ on the rectangular hyperbola $xy = c^2$ is :

asked Dec 11, 2018 by pady_1

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The equation of the ellipse whose foci are $(\pm 2, 0)$ and eccentricity is $1/2$ is :

asked Dec 11, 2018 by pady_1

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The equation of the tangent to the circle $x^2 +y^2 + 4x-4y + 4 =0$ which make equal intercepts on the positive co-ordinate axes, is :

asked Dec 11, 2018 by pady_1

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The greatest distance of the point $P(10, 7)$ from the circle $x^2 + y^2 - 4x - 2y - 20 = 0$ is :

asked Dec 11, 2018 by pady_1

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A straight line through the point $(2, 2)$ intersects the lines $\sqrt{3}x + y = 0$ and $\sqrt{3}x - y = 0$ at the points A and B. The equation to the line AB so that the OAB is equilateral, is :

asked Dec 11, 2018 by pady_1

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Three straight lines $2x+ 11y - 5 = 0, \; 24x + 7y - 20 = 0$ and $4x - 3y - 2 = 0$ :

asked Dec 11, 2018 by pady_1

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Let $f(2) = 4$ and $f'(2) = 4$ . Then $\begin{align} \displaystyle\lim_{x \to 2} \frac{xf(2) - 2 f(x)}{x-2} \end{align}$ is given by :

asked Dec 11, 2018 by pady_1

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