Recent questions tagged 2005

Energy levels A, B and C of a certain atom correspond to increasing values of energy i.e. ${E_A}<{E_B}<{E_C}$ . If${\lambda_1},{\lambda_2},{\lambda_3}$ are wave lengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct -

asked Jul 24, 2018 by pady_1

1 answer

Which of the following circular rods, (given radius r and length l) each made of the same energy material and whose ends are maintained at the same temperature will conduct most heat

asked Jul 24, 2018 by pady_1

1 answer

Carbon, Silicon and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $(E_g){_c}$ $(E_g)_Si$and $(E_g)_Ge$ respectively. Which one of the following relationships is true in their case .

asked Jul 24, 2018 by pady_1

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The total energy of an electron in the first excit state of hydrogen atom is about –3.4eV. Its kinetic energy in this state is-

asked Jul 24, 2018 by pady_1

1 answer

The circular motion of a particle with constant speed is-

asked Jul 24, 2018 by pady_1

2 answers

Choose the only false statement from the following-

asked Jul 24, 2018 by pady_1

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Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54Å. The value of lattice constant for this lattice is-

asked Jul 24, 2018 by pady_1

1 answer

In any fission process the ratio mass of fission products is- mass of parent nucleus

asked Jul 24, 2018 by pady_1

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The moment of inertia of a uniform circular disc o radius 'R' and mass 'M' about an axis passing from the edge of the disc and normal to the disc is-

asked Jul 24, 2018 by pady_1

2 answers

For the network shown in the figure the value of the current i is –

asked Jul 24, 2018 by pady_1

1 answer

For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is -

asked Jul 24, 2018 by pady_1

1 answer

If ${\lambda v}>{\lambda x}>{\lambda m}$ represent the wavelengths of visible light, x-rays and microwaves respectively, then-

asked Jul 24, 2018 by pady_1

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The ratio of the dimension of Planck's constant and that of the moment of inertia is the dimension of :

asked Jul 24, 2018 by pady_1

2 answers

The temperature of inversion of a thermocouple is $620^{\circ}C$ and the neutral temperature is $300^{\circ}C$. What is the temperature of cold junction :

asked Jul 24, 2018 by pady_1

1 answer

A particle executing simple harmonic motion of amplitude 5 cm has maximum speed of 31.4 cm/s. The frequency of its oscillation is :

asked Jul 24, 2018 by pady_1

1 answer

When a wire of uniform cross-section a, length l and resistance R is bent into a complete circle, resistance between any two of diametrically opposite points will be -

asked Jul 24, 2018 by pady_1

1 answer

Two vibrating tuning forks produce progressive waves given by $y_1=4\;sin\; 500\; \pi t$ and $y_2=2\;sin\;506\; \pi t$ Number of beats produced per minute is

asked Jul 24, 2018 by pady_1

1 answer

If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by $\mu_d, \mu_p$ and $\mu_f$ respectively, then

asked Jul 24, 2018 by pady_1

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If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by $\mu_d$, $\mu_p$ and $\mu_f$ respectively, then

asked Jul 24, 2018 by pady_1

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Two batteries, one of emf 18 volts and internal resistance $2\Omega$ and the other of emf 12 volt and internal resistance $1\Omega$, are connected as shown. The voltmeter V will record a reading of.

asked Jul 24, 2018 by pady_1

1 answer

Which of the following processes is reversible

asked Jul 24, 2018 by pady_1

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In a circuit L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45º. The value of C is -

asked Jul 24, 2018 by pady_1

1 answer

In the reaction$^{2}_{1}H + ^{3}_{1}H\rightarrow^{4}_{2}He +^{1}_{0}n$. If the binding energies of$^{2}_{1}H$ ,$^{3}_{1}H$ and $^{4}_{2}He$ are respectively a, b and c (in MeV), then the energy (in MeV) released in this reaction is

asked Jul 24, 2018 by pady_1

1 answer

Zener diode is used for:-

asked Jul 24, 2018 by pady_1

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The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5eV. According to Einstein's equation, the metals which will emit photo electrons for a radiation of wavelength $4100 A^{\circ}$ is/are-

asked Jul 24, 2018 by pady_1

1 answer

If $\large\frac{dy}{dx}=\frac{y+ x \tan \Large\frac{y}{x}}{x}$ then $\sin \large\frac{y}{x}$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

Observe the following statements:I. If $dy+2xy\;dx=2e^{-x^{2}} dx $ then $ye^{x^{2}}=2x+c$ II. If $ye^{-x^{2}}-2x=c$ then $dx=(2e^{-x^{2}}-2xy)dy$ Which of the following is a correct statement ?

asked Nov 13, 2013 by meena.p

1 answer

If $x^2 y-x^3 \large\frac{dy}{dx}$$=y^4 \cos x$ then $x^3\;y$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

If $dx+dy=(x+y)(dx-dy)$ then $\log (x+y)$ is equal to:

asked Nov 13, 2013 by meena.p

1 answer

The area (in square units) bonded by the curves $y^2=4x$ and $x^2=4y$ in the plane is :

asked Nov 13, 2013 by meena.p

1 answer

If $\int \sin ^{-1} \bigg( \large\frac{2x}{1+x^2}\bigg) $$dx-=f(x)-\log (1+x^2)+c$ then $f(x) $ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

$\int \limits_0^{\pi} \large\frac{\theta \sin \theta}{1+\cos ^2 \theta} $$ d \theta$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

$\int \limits_0^{\pi/2} \large\frac{200 \sin x+100 \cos x}{\sin x+\cos x}$$dx$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

$\int \large\frac{x^{49} \tan^{-1} (x^{50})}{(1+x^{100})}$$dx=k(\tan^{-1}(x^{50})^2+c$ then k is equal to :

asked Nov 13, 2013 by meena.p

1 answer

If $\int \large\frac{\sin x}{\cos x(1+\cos x)dx}$$=f(x)+c$ then $f(x)$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

If $u= \sin^{-1} \bigg(\large\frac{x}{y}\bigg)$$+\tan^{-1} \bigg(\large\frac{y}{x}\bigg)$, then the value of $x \large\frac{\partial u}{\partial x}$$+y \large\frac{\partial u}{\partial y}$ is :

asked Nov 13, 2013 by meena.p

1 answer

Observe the following statements :A : $f(x)=2x^3-9x^2+12x-3$ is increasing outside the interval $(1,2)$ R : f'(x) < 0 for $x \in (1,2)$ Then which of the following is true ?

asked Nov 13, 2013 by meena.p

1 answer

The radius of a circular plate is increasing at the rate of $0.01\;cm/sec$ when the radius is $12\; cm$. Then the rate at which the area increases, is :

asked Nov 13, 2013 by meena.p

1 answer

A stone thrown upwards, has its equation of motion $s=490t-4.9t^2$. Then the maximum height reached by it , is:

asked Nov 13, 2013 by meena.p

1 answer

If $x \sqrt {1+y}+y \sqrt {1+x}=0$ then $\large\frac{dy}{dx}$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

If $f(x) =10 \cos x +(13+2x) \sin x$ then $f''(x)+f(x)$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

Observe the following statements: $I. f(x) =ax^{41}+bx^{-40}=> \large\frac{f''(x)}{f(x)}$$=1640\;x^{-2} \quad II. \large\frac{d}{dx} $$\tan ^{-1} \bigg(\large\frac{2x}{1-x^2}\bigg)=\frac{1}{1+x^2}$Which of the following is correct ?

asked Nov 13, 2013 by meena.p

1 answer

If $R \to R$ is an even function which is twice differentiable on R and $f''(\pi)=1,$ then $f''(-\pi)$ is equal to :

asked Nov 13, 2013 by meena.p

1 answer

If $f: R \to R $ is defined by $f(x)= \left\{ \begin{array}{1 1} \large\frac{x+2}{x^2-3x+2} & \quad if & \quad x\in R -[-1,-2] \\ -1 & \quad if & \quad x=-2 \\ 0 & \quad if & \quad x=-1 \end{array} \right. $ then $f$ is continuous on the set :

asked Nov 13, 2013 by meena.p

1 answer

If $f: R \to R $ is defined by $f(x)= \left\{ \begin{array}{1 1} \large\frac{x-2}{x^2-3x+2} & \quad if & \quad x\in R -[1,2] \\ 2 & \quad if & \quad x=2 \\ 1 & \quad if & \quad x=2 \end{array} \right. $ then $\lim \limits_{x \to 2} \large\frac{f(x)-f(2)}{x-2}=$

asked Nov 13, 2013 by meena.p

1 answer

$\lim \limits_{x \to 0} x^2 \sin \large\frac{\pi}{x}$ is equal to :

asked Nov 12, 2013 by meena.p

1 answer

Which of the following equations gives a circle?

asked Nov 12, 2013 by meena.p

1 answer

The cartesian from of the polar equation $\theta=\tan^{-1} 2$ is :

asked Nov 12, 2013 by meena.p

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The line among the following which touches the parabola $y^2=4ax,$ is :

asked Nov 12, 2013 by meena.p

1 answer

The parabola with directrix $x+2y-1=0$ and focus (1,0) is :

asked Nov 12, 2013 by meena.p

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