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A source of sound emitting a note of frequency 200 Hz moves towards an observer with a velocity v equal to the velocity of sound. If the observer also moves away from the source with the same velocity v, the apparent frequency heard by the observer is

Calculate the amount of heat required to convert 1.00 kg of ice at $-{10}^{\circ }$C into steam at ${100}^{\circ }$C at normal pressure. $(S_{ice}=2100Jk{g}^{-1}{K}^{-1},S_{water}=4200Jk{g}^{-1}{K}^{-1}L{f}_{ice}=3.36\times {10}^{5}Jk{g}^{-1}L{v}_{water}=2.25\times {10}^{6}Jk{g}^{-1})$

Water flows through two identical tubes A and B. A volume V₀ of water passes through the tube A and 2 V₀ through B in a given time. Which of the following may be correct?

What is the phase difference between the two simple harmonic motions whose displacement – time graphs are shown in fig ?

A body dropped from the top of a tower falls through 40m during the last 2s of its fall. The height of the tower is ($g=10m/s^2$)

Which of the following changes decrease the vaporise pressure of water kept in a sealed vessel?

(a) Decreasing the quantity of water

(b) Adding salt to the water

(c) Decreasing the volume of the vessel to one-half

(d) Decreasing the temperature of the water

The length of two open organ pipes are l and ( l + $\Delta l)$ respectively. Neglecting

end correction, the frequency of beats between them will be approximately

(Here v is the speed of sound)

[MP PET 1994; BHU 1995]

A car moving on a horizontal road may be thrown out of the road in taking a turn

The orbital diagram in which both Pauli's exclusion principle and Hund's rule are violated is:

Let $\overrightarrow{v},v_{rms}$ and $v_2$ respectively denote the mean speed, root mean square speed and most probable speed of the molecules in an ideal monoatomic gas at absolute temperature T. The mass of a molecule is m. Then

If the roots of $x^2+bx+c$ = 0 are two consecutive integers then $b^2$ - 4c =

A p-type conductor is created on doping silicon with

Two coherent sources $S_1$ and $S_2$ which emit sound of wavelength $\lambda$ in phase are separated by $2\lambda$. A circular wire of large radius is placed in such a way that $S_1{S}_2$ lies in its plane and the middle point of $S_1{S}_2$ is at the centre of the wire as shown below. Find the angular position $\theta$ (in first quadrant) on the wire for which destructive interference takes place.
[Assume the radius of ring $R>>2\lambda$]

Consider six wires carrying same current coming into or out of the page. Rank the line integral of the magnetic field (from most positive to most negative) taken counter-clockwise around each loop shown.

A body of mass 2 kg has an initial velocity of 3 m/s along OE and it is subjected to a force of 4

Newton’s in OF direction perpendicular to OE. The distance of the body from O after 4 seconds will be

The potential barrier existing across an unbiased p-n junction is 0.2 volt. What minimum kinetic energy a hole should have to diffuse from the p-side to the n-side if (a) the junction is unbiased, (b) the junction is forward-biased at 0.1 volt and (c) the junction is reverse- biased at 0.1 volt ?

Two charges $2.0\times {10}^{-6}$ are placed a ta separation of 10 cm. Where should a third charge be placed such that it experienes no net orce due to these charges?

A body of mass 3 kg is dropped from a height of 1m. The K.E of the body before touching the ground is: (Take g = 10 ms^2).

The minimum deviations suffered by red, yellow and violet beams passing through an equilateral transparent prism are ${38.4}^{\circ },{38.7}^{\circ }$ and ${39.2}^{\circ }$ respectively. Calculate the dispersive power of the medium.

Find the equivalent capacitance of the system shown figure (31-E8) between the points a and b.

The maximum height of an oblique projectile is $8\text{m}$. The horizontal range is $24\text{m}$. The horizontal component of the velocity of projection is

If $\overrightarrow{a}=3\hat{i}+4\hat{j}$ and $\overrightarrow{b}=7\hat{i}+24\hat{j}$, then find the vector having the same magnitude as $\overrightarrow{b}$ and same direction as $\overrightarrow{a}$.

If ${\epsilon }_0\text{and}{\mu }_0$ represent the permittivity and permeability of vacuum and $\epsilon \text{and}\mu$ represent the permittivity and permeability of medium, the refractive index of the medium is given by

A rectangular coil of 20 turns and cross section area $25c{m}^2$ has a resistance of $100\Omega$. If the a magnetic field which is perpendicular to the plane of the coil changes at a rate of 1000 T/s, the current in the coil is:

Two coherent waves represented by $y_1=A\text{sin}(\frac{2\pi x_1}{\lambda }-\omega t+\frac{\pi }{6})$ and ${\lambda }_2=A\text{sin}(\frac{2\pi x_2}{\lambda }-\omega t+\frac{\pi }{8})$ are superposed. The path difference $(x{­}_1-x_2)$ to produce constructive interference $\left(nϵI\right)$.

A 100 W bulb B₁two 60 W bulb B₂ and B₃ are connected to a 250 V source as shown in the figure. Now W₁, W₂ and W₃ are the output powers of the bulbs B₁, B₂ and B₃ respectively. Then

Two tuning forks with natural frequencies of 340 Hz each move relative to a stationary observer. One fork moves away from the observer while the other moves towards him at the same speed. The observer hears beats of frequency 3 Hz. The speed of the tuning fork is (velocity of sound = 340 m/s)

In a YDSE fringes are observed by using light of wavelength 4800 $A^{\circ }$, if a glass plate ($\mu$ =1.5) is introduced in the path of one of the wave and another plate of same thickness is introduced in the path of the ($\mu$ = 1.8) other wave. The central fringe takes the position of fifth bright fringe. The thickness of plate will be

Correct truth table for given circuit is.

A solid cube floats in water half immersed and has small vertical oscillations of time period $\frac{\pi }{5}\text{s}$. Its mass $\left(\text{in kg}\right)$ is:
$(\text{Take}g=10{\text{ms}}^{-2})$

A ball of mass $2\text{kg}$ is suspended by a light string of length $10\text{m}$ as shown in the figure. It is imparted a horizontal velocity of $50\text{m/s}$ . Calculate the speed of the ball at point $\text{B}$. (Take $g=9.8{\text{m/s}}^2$ )

If $\frac{d\tan x}{dx}={\sec }^{2}x$, then $\int \frac{2}{1-{\sin }^{2}x}dx$ is equal to:

A block A can slide on a frictionless incline of angle $\theta$ and length l, kept inside an elevator going up with uniform velocity v in figure. Find the time taken by the block to slide down the length of the incline if it is released from the top of the incline.

The luminous flux of a monochromatic source of 1 W is 450 lumen $wat{t}^{-}1$. Find the relative luminosity at the wavelength emitted.

A ball is thrown upward from the top of a tower of height $50\text{m}$ with a velocity of $15\text{m/s}$. Find the time when it strikes the ground. Take $g=10\text{m}/s^2$.

A block of mass $10\text{kg}$ is suspended from a string of length $4\text{m}$. When pulled by a force $F$ along the horizontal from its midpoint, upper half of the string makes an angle ${45}^{\circ }$ with the vertical. The value of $F$ is

Three bodies A, B and C of masses m, m and $\sqrt{3}\text{m}$ respectively are supplied heat at a constant rate. The change in temperature $\theta$ versus time t graph for A, B and C are shown by I, II and III respectively. If their specific heat capacities are $S_A,S_B$ and $S_C$ respectively then which of the following relation is correct? (Initial temperature of body is $0^{\circ }C$)

There is a flat uniform triangular plate ABC such that $AB=4\text{cm},BC=3\text{cm}$ and $\angle ABC={90}^{\circ }$ as shown in the figure. The moment of inertia of the plate about AB, BC and CA is $I_1,I_2$ and $I_3$ respectively. The incorrect statement is

A force of 100 N is applied on a block of mass 3kg as shown below. The coefficient of friction between wall and the block is $\frac{1}{4}$. The friction force acting on the block is

A transparent cube of $15cm$ edge contains a small air bubble. Its apparent depth when viewed through one face is $6cm$ and when viewed through opposite face is $4cm$. The refractive index of material of cube is