Recent questions in Archives

The amount of arsenic pentasulphide that can be obtained when $35.5\;g$ arsenic acid is treated with excess $H_2S$ in the presence of conc. $HCl$ ( assuming 100% conversion) is

asked May 24, 2017 by meena.p

1 answer

The resistance of an electrical toaster has a temperature dependence given by $ R(T)=R_0 [1+α(T−T_0)] $ in its range of operation. At $T_0=300 K, R=100 Ω $and at$ T=500 K, R=120 Ω$. The toaster is connected to a voltage source at $200 V$ and its temperature is raised at a constant rate from $300$ to $ 500 K$ in $30 s$. The total work done in raising the temperature is

asked May 23, 2017 by priyanka.c

1 answer

Figure shows a network of capacitors where the numbers indicates capacitances in micro Farad. The value of capacitance $C$ if the equivalent capacitance between point $A$ and $B$ is to be $1 µF$ is :

asked May 23, 2017 by priyanka.c

1 answer

An unknown transistor needs to be identified as a $npn$ or $pnp$ type. A multimeter, with $+ve$ and $−ve$ terminals, is used to measure resistance between different terminals of transistor. If terminal 2 is the base of the transistor then which of the following is correct for a $pnp$ transistor ?

asked May 23, 2017 by meena.p

1 answer

An experiment is performed to determine the $I - V$ characteristics of a Zener diode,which has a protective resistance of $R=100 \Omega$, and a maximum power of dissipation rating of $1 \;W$. The minimum voltage range of the DC source in the circuit is :

asked May 23, 2017 by meena.p

1 answer

Within a spherical charge distribution of charge density $ρ(r), N $ equipotential surfaces of potential $V_0, V0+∆V, V_0+2∆V, .......... V_0+N∆V (∆V>0)$, are drawn and have increasing radii$ r_0, r_1, r_2,..........r_N$, respectively. If the difference in the radii of the surfaces is constant for all values of $V_0$ and $∆V$ then :

asked May 23, 2017 by priyanka.c

1 answer

A toy-car, blowing its horn, is moving with a steady speed of $5 m/s$, away from a wall. An observer, towards whom the toy car is moving, is able to hear $5$ beats per second. If the velocity of sound in air is $340 m/s$, the frequency of the horn of the toy car is close to :

asked May 23, 2017 by priyanka.c

1 answer

In an engine the piston undergoes vertical simple harmonic motion with amplitude $7 cm$. A washer rests on top of the piston and moves with it. The motor speed is slowly increased. The frequency of the piston at which the washer no longer stays in contact with the piston, is close to :

asked May 23, 2017 by priyanka.c

1 answer

To find the focal length of a convex mirror, a student records the following data :The focal length of the convex lens is $f_1$ and that of mirror is $f_2$. Then taking index correction to be negligibly small, $f_1$ and $f_2$ are close to :

asked May 23, 2017 by meena.p

1 answer

Which of the following shows the correct relationship between the pressure $‘P’$ and density $ρ$ of an ideal gas at constant temperature ?

asked May 23, 2017 by priyanka.c

1 answer

To know the resistance G of a galvanometer by half deflection method, a battery of emf $V_E$ and resistance $R$ is used to deflect the galvanometer by angle $\theta$. If a shunt of resistance $S$ is needed to get half deflection then $G, R$ and $S$ are related by the equation :

asked May 23, 2017 by meena.p

1 answer

A uniformly tapering conical wire is made from a material of Young’s modulus $Y$ and has a normal, unextended length $L$. The radii, at the upper and lower ends of this conical wire, have values $R$ and $3R$,respectively. The upper end of the wire is fixed to a rigid support and a mass $M$ is suspended from its lower end. The equilibrium extended length, of this wire,would equal :

asked May 23, 2017 by meena.p

1 answer

A carnot freezer takes heat from water at $0^oC$ inside it and rejects it to the room at a temperature of $27^oC$. The latent heat of ice is $336 \times 10^3 J kg^{-1}$. The latent heat of ice is $336 \times 10^3 J kg$. If $5 kg$ of water at $ 0^oC $ is converted into ice at $0^oC$ by the freezer, then the energy consumed by the freezer is close to :

asked May 23, 2017 by priyanka.c

1 answer

A simple pendulum made of a bob of mass m and a metallic wire of negligible mass has time period $2\;s$ at $T=0^{\circ}C$. If the temperature of the wire is increased and the corresponding change in its time period is plotted against its temperature, the resulting graph is a line of slope $S$. If the coefficient of linear expansion of metal is $\alpha$ then the value of $S$ is :

asked May 23, 2017 by meena.p

1 answer

An audio signal consists of two distinct sounds : one a human speech signal in the frequency band of $200\; Hz$ to $2700\; Hz$, while the other is a high frequency music signal in the frequency band of $10200\; Hz$ to $15200\; Hz$. The ratio of the AM signal bandwidth required to send both the signals together to the AM signal bandwidth required to send just the human speech is :

asked May 23, 2017 by meena.p

1 answer

The truth table given in fig. represents :

asked May 23, 2017 by meena.p

1 answer

A bottle has an opening of radius $a$ and length $b$. A cork of length $b$ and radius $(a + \Delta a)$ where is $(\Delta << a)$ is compressed to fit into the opening completely (See figure). If the bulk modulus of cork is $B$ and frictional coefficient between the bottle and cork is $\mu$ then the force needed to push the cork into the bottle is :

asked May 23, 2017 by priyanka.c

1 answer

A hydrogen atom makes a transition from $n=2$ to $n=1$ and emits a photon. This photon strikes a doubly ionized lithium atom $(z=3)$ in excited state and completely removes the orbiting electron. The least quantum number for the excited state of the ion for the process is :

asked May 22, 2017 by meena.p

1 answer

When photons of wavelength $\lambda_1$ are incident on an isolated sphere, the corresponding stopping potential is found to be V. When photons of wavelength $\lambda_2$ are used, the corresponding stopping potential was thrice that of the above value. If light of wavelength $\lambda_3$ is used then find the stopping potential for this case :

asked May 22, 2017 by meena.p

1 answer

An astronaut of mass $m$ is working on a satellite orbiting the earth at a distance $h$ from the earth’s surface. The radius of the earth is $R$, while its mass is $M$. The gravitational pull $F_G$ on the astronaut is

asked May 22, 2017 by priyanka.c

1 answer

In the figure shown ABC is a uniform wire. If centre of mass of wire lies vertically below point A, then $\frac{BC}{AB}$ is close to :

asked May 22, 2017 by priyanka.c

1 answer

In Young’s double slit experiment, the distance between slits and the screen is $1.0\; m$ and monochromatic light of $600\; nm$ is being used. A person standing near the slits is looking at the fringe pattern. When the separation between the slits is varied, the interference pattern disappears for a particular distance $d_0$ between the slits. If the angular resolution of the eye is $\large\frac{1^{\circ}}{60}$ the value of $d_0$ is close to

asked May 22, 2017 by meena.p

1 answer

A convex lens, of focal length 30 cm, a concave lens of focal length 120 cm, and a plane mirror are arranged as shown. For an object kept at a distance of 60 cm from the convex lens, the final image, formed by the combination, is a real image, at a distance of :

asked May 22, 2017 by meena.p

1 answer

Microwave oven acts on the principle of :

asked May 22, 2017 by meena.p

1 answer

A series $LR$ circuit is connected to a voltage source with $V(t)=V_0\; sin \omega t$. After very large time, current I(t) behaves as $\bigg( t_0 >> \large\frac{L}{R} \bigg)$:

asked May 22, 2017 by meena.p

1 answer

A $50 \Omega$ resistance is connected to a battery of $5 \;V$. A galvanometer of resistance $100\;Ω$ is to be used as an ammeter to measure current through the resistance, for this a resistance rs is connected to the galvanometer. Which of the following connections should be employed if the measured current is within $1 \%$ of the current without the ammeter in the circuit ?

asked May 22, 2017 by meena.p

1 answer

Velocity-time graph for a body of mass 10 kg is shown in figure. Work-done on the body in first two seconds of the motion is :

asked May 22, 2017 by priyanka.c

1 answer

Concrete mixture is made by mixing cement, stone and sand in a rotating cylindrical drum. If the drum rotates too fast, the ingredients remain stuck to the wall of the drum and proper mixing of ingredients does not take place. The maximum rotational speed of the drum in revolutions per minute(rpm) to ensure proper mixing is close to : </br> (Take the radius of the drum to be 1.25 m and its axle to be horizontal) :

asked May 22, 2017 by priyanka.c

1 answer

A particle of mass $ M $is moving in a circle of fixed radius $R$ in such a way that its centripetal acceleration at time $t$ is given by $n^2 R t^2$ where $ n$ is a constant. The power delivered to the particle by the force acting on it, is:

asked May 22, 2017 by priyanka.c

1 answer

A, B, C and D are four different physical quantities having different dimensions. Now of them is dimensionless. But we know that the equation AD = C in (BD) holds true. Then which of the combination is not a meaningful quantity ?

asked May 22, 2017 by priyanka.c

1 answer

A magnetic dipole is acted upon by two magnetic fields which are inclined to each other at an angle of $75^{\circ}$. One of the fields has a magnitude of $15\; mT$. The dipole attains stable equilibrium at an angle of $30^{\circ}$ with this field. The magnitude of the other field (in mT ) is close to :

asked May 19, 2017 by meena.p

1 answer

In the circuit shown, the resistance r is a variable resistance. If for $r=f R$, the heat generation in r is maximum then the value of f is :

asked May 19, 2017 by meena.p

1 answer

Three capacitors each of $4 \mu F$ are to be connected in such a way that the effective capacitance is $6 \mu F$. This can be done by connecting them :

asked May 19, 2017 by meena.p

1 answer

The potential (in volts) of a charge distribution is given by $V(z) =30-5z^2$ for $|z| \leq 1\;m$$V(z) =35-10|z|$ for $|z| \geq 1\;m$ $V(z)$ does not depend on x and y .If this potential is generated by a constant charge per unit volume $\rho_0,$ (in units of $\in_0$) which is spread over certain region ,then choose the correct statement

asked May 18, 2017 by meena.p

1 answer

Two engines pass each other moving in opposite directions with uniform speed of $30\;m/s$. One of them is blowing a whistle of frequency $540\; Hz$. Calculate the frequency heard by driver of second engine before they pass each other. Speed of sound is $330\; m/sec$

asked May 18, 2017 by meena.p

1 answer

Two particles are performing simple harmonic motion in a straight line about the same equilibrium point. The amplitude and time period for both particles are same and equal to $A$ and $T$, respectively. At time $t=0$ one particle has displacement $A$ while the other one has displacement $\large\frac{−A}{2}$ and they are moving towards each other. If they cross each other at time t, then t is :

asked May 18, 2017 by meena.p

1 answer

The ratio of work done by an ideal monoatomic gas to the heat supplied to it in an isobaric process is :

asked May 18, 2017 by meena.p

1 answer

$200\; g$ water is heated from $40^{\circ}C$ to $60^{\circ}C$. Ignoring the slight expansion of water, the change in its internal energy is close to(Given specific heat of water$=4184\; J/kg/K)$ :

asked May 18, 2017 by meena.p

1 answer

Consider a water jar of radius $R$ that has water filled up to height $H$ and is kept on a stand of height h (see figure). Through a hole of radius $r (r << R)$ at its bottom, the water leaks out and the stream of water coming down towards the ground has a shape like a funnel as shown in the figure.If the radius of the cross-section of water stream when it hits the ground is $x$. Then :

asked May 18, 2017 by meena.p

1 answer

Figure shows elliptical path abcd of a planet around the sun $S$ such that the area of triangle csa is $\large\frac{1}{4}$ the area of the ellipse. (See figure) With db as the semimajor axis, and ca as the semiminor axis. If $t_1$ is the time taken for planet to go over path abc and $t_2$ for path taken over cda then :

asked May 18, 2017 by meena.p

1 answer

A cubical block of side $30\;cm$ is moving with velocity $2 \;ms^{−1}$ on a smooth horizontal surface. The surface has a bump at a point $O$ as shown in figure. The angular velocity (in rad/s) of the block immediately after it hits the bump, is :

asked May 18, 2017 by meena.p

1 answer

A car of weight $W$ is on an inclined road that rises by $100\; m$ over a distance of $1\; km$ and applies a constant frictional force $\large\frac{W}{20}$ on the car. While moving uphill on the road at a speed of $10 ms^{−1},$ the car needs power $P$. If it needs power $\frac{P}{2}$ while moving downhill at speed $v$ then value of v is :

asked May 18, 2017 by meena.p

1 answer

A rocket is fired vertically from the earth with an acceleration of $2g,$ where $g$ is the gravitational acceleration. On an inclined plane inside the rocket, making an angle $\theta$. With the horizontal , a point object of mass $m$ is kept. The minimum coefficient of friction $\mu_{min}$ between the mass and the inclined surface such that he mass does not move is :

asked May 18, 2017 by meena.p

1 answer

Which of the following option correctly describes the variation of the speed v and acceleration ‘a’ of a point mass falling vertically in a viscous medium that applies a force $F =−kv,$ where ‘k’ is a constant, on the body ? (Graphs are schematic and not drawn to scale)

asked May 18, 2017 by meena.p

1 answer

In the following ‘I’ refers to current and other symbols have their usual meaning. Choose the option that corresponds to the dimensions of electrical conductivity :

asked May 18, 2017 by meena.p

1 answer

All the students of a class performed poorly in Mathematics. The teacher decided to give grace marks of 10 to each of the students. Which of the following statistical measures will not change even after the grace marks were given ?

asked Apr 19, 2017 by meena.p

1 answer

The expression $\large\frac{\tan A}{1- \cot A} +\frac{\cot A}{1- \tan A}$ can be written as :

asked Apr 19, 2017 by meena.p

1 answer

If $y= \sec (\tan ^{-1}x)$, then $\large\frac{dy}{dx}$ at $x=1$ is equal to :

asked Apr 19, 2017 by meena.p

1 answer

Given : A circle,$2x^2+2y^2=5$ and an parabola , $y^2 = 4 \sqrt 5 x$ <br> Statement − I : An equation of a common tangent to these curves is $y =x +\sqrt 5$ <br> Statement − II : If the line, $y= mx+ \large\frac{\sqrt 5}{m} $$(m \neq 0)$ is their common tangent, then ‘m’ satisfies $m^4- 3m^2+2=0$

asked Apr 19, 2017 by meena.p

1 answer

The intercepts on x−axis made by tangents to the curve, $y= \int \limits_0^x |t| dt , x \in R$ which are parallel to the line $y = 2x,$ are equal to

asked Apr 19, 2017 by meena.p

1 answer

Ask Questions, Get Answers