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Suppose the drift velocity $v_d$ in a material varied with the applied electric field $E$ as $v_d \alpha E$ ; .Then $V - I$ graph for a wire made of such a material is best given by :

asked Sep 25, 2015 by meena.p

1 answer

If the capacitance of a nanocapacitor is measured in terms of a unit 'u' made by combining the electronic charge e, Bohr radius $a_0$ , Plancks constant h and speed of light c then :

asked Sep 25, 2015 by meena.p

1 answer

Shown in the figure are two point charges $+Q$ and $-Q$ inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If $\sigma_1$ is the surface charge on the inner surface and $Q_1$ net charge on it and $\sigma_2$ the surface charge on the outer surface and $Q_2$ net charge on it then :

asked Sep 25, 2015 by meena.p

1 answer

A thin disc of radius $b=2a$ has a concentric hole of radius a in it (see figure). It carries uniform surface charge s on it. If the electric field on its axis at height $h (h<<a)$ from its centre is given as 'Ch' then value of C is :

asked Sep 25, 2015 by meena.p

1 answer

A bat moving at $10\; ms^{-1}$ towards a wall sends a sound signal of $8000 \;Hz$ towards it. On reflection it hears a sound of frequency f. The value of f in Hz is close to (speed of sound $=320 ms^{-1}$ )

asked Sep 25, 2015 by meena.p

1 answer

A simple harmonic oscillator of angular frequency $2\;rad \;s^{-1}$ is acted upon by an external force $F=\sin t\; N$ . If the oscillator is at rest in its equilibrium position at $t=0$ ,its position at later times is proportional to

asked Sep 25, 2015 by meena.p

1 answer

In an ideal gas at temperature T, the average force that a molecule applies on the walls of a closed container depends on T as $T^q$ . A good estimate for q is :

asked Sep 25, 2015 by meena.p

1 answer

An ideal gas goes through a reversible cycle $a \to b \to c \to d$ has the V - T diagram shown below. Process $d \to a$ and $b \to c$ are adiabatic.The corresponding P - V diagram for the process is (all figures are schematic and not drawn to scale) :

asked Sep 25, 2015 by meena.p

1 answer

If two glass plates have water between them and are separated by very small distance (see figure), it is very difficult to pull them apart. It is because the water in between forms cylindrical surface on the side that gives rise to lower pressure in the water in comparison to atmosphere. If the radius of the cylindrical surface is R and surface tension of water is T then the pressure in water between the plates is lower by:

asked Sep 25, 2015 by meena.p

1 answer

If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter $\large\frac{2}{\sqrt {\pi}}$ cm then the Reynolds number for the flow is (density of water= $10^{3}\; kg/m^3$ and viscosity of water= $10^{-3}$ Pa.s) close to :

asked Sep 25, 2015 by meena.p

1 answer

A very long (length L) cylindrical galaxy is made of uniformly distributed mass and has radius $R (R<<L)$ . A star outside the galaxy is orbiting the galaxy in a plane perpendicular to the galaxy and passing through its centre. If the time period of star is T and its distance from the galaxys axis is r, then :

asked Sep 25, 2015 by meena.p

1 answer

Consider a thin uniform square sheet made of a rigid material. If its side is a, mass m and moment of inertia I about one of its diagonals, then :

asked Sep 25, 2015 by meena.p

1 answer

A uniform solid cylindrical roller of mass m is being pulled on a horizontal surface with force F parallel to the surface and applied at its centre. If the acceleration of the cylinder is a and it is rolling without slipping then the value of F is :

asked Sep 25, 2015 by meena.p

1 answer

A block of mass $m=0.1\;kg$ is connected to a spring of unknown spring constant k. It is compressed to a distance x from its equilibrium position and released from rest. After approaching half the distance $\bigg(\large\frac{x}{2} \bigg)$ from equilibrium position, it hits another block and comes to rest momentarily, while the other block moves with a velocity $3 ms^{-1}$ . The total initial energy of the spring is :

asked Sep 25, 2015 by meena.p

1 answer

A block of mass $m=10\;kg$ rests on a horizontal table. The coefficient of friction between the block and the table is $0.05$ .When hit by a bullet of mass $50\; g$ moving with speed $v,$ that gets embedded in it, the block moves and comes to stop after moving a distance of $2\; m$ on the table. If a freely falling object were to acquire speed $\large\frac{v}{10}$ after being dropped from height H, then neglecting energy losses and taking $g=10 ms^{-2}$ , the value of H is close to :

asked Sep 25, 2015 by meena.p

1 answer

If a body moving in a circular path maintains constant speed of $10\; ms^{-1}$ , then which of the following correctly describes relation between acceleration and radius ?

asked Sep 25, 2015 by meena.p

1 answer

x and y displacements of a particle are given as $x(t)=a \sin \omega t$ and $y(t)=a \sin 2 \omega t$ . Its trajectory will look like

asked Sep 25, 2015 by meena.p

1 answer

Two fixed friction less inclined plane making $30^{\circ}$ and $60^{\circ}$ with vertical are shown . Two blocks A and B are placed on the two planes . What is the relative vertical acceleration of a with respect to B.

asked May 13, 2015 by meena.p

1 answer

The time period of oscillation of a uniform rod with length l pivoted at one end is

asked May 13, 2015 by meena.p

1 answer

A jet of air moving with a speed of $50\;m/s$ with diameter $10\;mm$ strikes a disc kept vertical what is the force exerted by the air jet on the disc. (density of air $1.03\;kg/m^3)$

asked May 13, 2015 by meena.p

1 answer

If the radius of earth were increased by a factor of 2 keeping mass constant , by what factor would its density have to be changed to keep of the same .

asked May 12, 2015 by meena.p

1 answer

The coordinates of center of mass of uniform lamina shown in figure is

asked May 12, 2015 by meena.p

1 answer

A block of mass m is connected to a spring and passed over a pulley as shown in figure. The block is released from rest with the spring outstretched. Force constant of spring is k. Find the maximum extension in the spring .

asked May 12, 2015 by meena.p

1 answer

A object A is at a point $x=3\;m$ and $y= 1.25 \;m$ from a fixed point. At time $t=0$ the object starts moving with an acceleration of $1.5 \;m/s^2$ in the +ve x direction . At the same instant a stone is projected from origin with a velocity $\overrightarrow{u}$ and hits the object during its downward motions at an angle of $45^{\circ}$ to the horizontal. Find the time after which the store hots the object $[g= 10\;m/s^2]$

asked May 12, 2015 by meena.p

1 answer

One end of a copper rod of length 1 m and cross sectional area $4.0 \times 10^{-4} m^2$ is maintained at $100^{\circ}C$ At the other end of the ice is kept at $0^{\circ}C$ .Neglecting loss of heat from surrounding the mass of ice melted in half hour is $[ K_{cu}=401 \;w/m k\;and\;L_f =3.35 \times 10^5 \;J/kg]$

asked May 12, 2015 by meena.p

1 answer

Two cars A and b are travelling in same direction with velocities $V_1$ and $V_2 (V_1 > V_2)$ when the car A is at a distance d ahead of car B , the driver of the car A applied the broke producing a uniform retardation a. There will be no collision when

asked May 12, 2015 by meena.p

1 answer

Two short magnets P and Q are arranged such that centres are on the x- axis and are separated by large distance the magnetic axis of P and Q are along X and Y axes respectively. At a point $R_1$ mid way between their centers , the magnitude of total induction at R due to both magnet is $ (if B is magnitude of induction due to a)

asked May 12, 2015 by meena.p

1 answer

A photo diode is made from a semiconductor with band gap of $2/5 \;eV$ , which of the following ranges of wavelength it can detected ?

asked May 12, 2015 by meena.p

1 answer

Two white point dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately what is the maximum distanceat which thes dots can be resolved by the eye (wave length of light = 500 nm)

asked May 12, 2015 by meena.p

1 answer

A prism is made of material of refractive index $\sqrt 3$ . The angle of minimum derivation is equal to angle of prism, then the angle of prism is .

asked May 11, 2015 by meena.p

1 answer

Separation between plates of a parallel plate capacitors is 'd'. It is charged a battery then disconnected ,a dielectric slab of thickness $\large\frac{d}{3}$ and constant 3 is introduced in it . The fractional change in energy .

asked May 11, 2015 by meena.p

1 answer

If a photo cell is illuminated with a radiation of $1240 \;A^{\circ}$ , the stopping potential is found to be $6V$ , then the work function of the emitter and the threshold wavelength are

asked May 11, 2015 by meena.p

1 answer

The magnetic field at O

asked May 11, 2015 by meena.p

1 answer

The radius of first orbit of hydrogen atom is $0.53 A^{\circ}$ and the electron is executing $6.54 \times 10^5$ revolutions per second . The magnetic moment of electron will be

asked May 11, 2015 by meena.p

1 answer

In a PNP transistor working as a common base amplifier current gains $0.96$ and emitter current is $7.2 \;mA$ . The base current is

asked May 11, 2015 by meena.p

1 answer

The amount of active substance reduces to $\large\frac{1}{64}$ of its initial value in 15 hours . What is the half life?

asked May 11, 2015 by meena.p

1 answer

At a temperature of $30^{\circ}$ the susceptibility of a ferromagnetic material is found to be x. What is its susceptibility at $333^{\circ}$

asked May 11, 2015 by meena.p

1 answer

This is

asked May 11, 2015 by meena.p

1 answer

The electric field strength in an electro magnetic wave is $10^4 V/m$ The magnetic strength (in Tesla) is

asked May 11, 2015 by meena.p

1 answer

A negetively charged oil drop of mass $8 \times 10^{-15} \;kg$ remains suspended in a uniform field of $2\times 10^4 \;v/m$ in millikani experiment . The number of electrons making up the charge is $(g= 10\;m/s^2)$

asked May 11, 2015 by meena.p

1 answer

A box of mass $40\;kg$ is placed on an open truck . The coefficient of friction between the box and the surface of the truck is $0.15$ with what maximum acceleration can the truck move so that the box does not slide out.

asked May 11, 2015 by meena.p

1 answer

A car approaching a crossing at a speed of $20 \;m/s$ sounds a horn of frequency of $500\;hz$ . When the car is $80 \;m$ from the crossing. Speed of sound in air is $320\;m/s$ An observer is at a distance of $60\;m$ from the crossing on a road perpendicular to the direction of motion of car. What frequency is heard by the observer .

asked May 11, 2015 by meena.p

1 answer

The resistor in which maximum heat will be produced is

asked May 11, 2015 by meena.p

1 answer

plot the V-T graph corresponding to the P- T graph for a ideal gas shown in figure .

asked May 11, 2015 by meena.p

1 answer

Two thin lenses of same radius of curvature $R= 15\;cm$ of different nature made of different material one having refractive index $\mu_1 =\large\frac{2}{3}$ and another $\mu_2$ . The lenses are kept in contact and immersed in water of refractive index $\mu_w = \large\frac{3}{4}$ . The focal length of the system of lenses in water is $30\;cm$ . What is the value of $\mu_2$

asked May 11, 2015 by meena.p

1 answer

A simple pendulum is suspended from ceiling of a lift. When the lift is at rest , its time period is $T_0$ with what acceleration should lift be acceleration upward in order to reduce it, time period to $T/2$ ?

asked May 11, 2015 by meena.p

1 answer

A uniform solid sphere is rotating with angular speed of $\omega_0$ about a diameter . The temperature of the solid is suddenly increased by $100^{\circ}$ . What will be the new angular speed. $(\alpha = 3 \times 10^{-4}\;per ^{\circ}c)$

asked May 11, 2015 by meena.p

1 answer

Two circular plates of radius $5\;cm$ each , have a $0.01 \;mm$ thick water film between them . What will be the force required to separated the plates (surface tension of water = 73 dynes /cm)

asked Apr 30, 2015 by meena.p

1 answer

Two spheres of volume $500\;cc$ each of relative density $0.6$ and $1.2$ are connected by string and the combination is immersed in a liquid. The tension in the string is

asked Apr 30, 2015 by meena.p

1 answer

In the circuit as shown in the figure what is the potential difference between P and Q.

asked Apr 30, 2015 by meena.p

1 answer

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