Recent questions in Physics

Two coherent sources whose intensity ratio is $64 :1 $ produce interference fringes. The ratio of intensities of maxima and minima is :

asked Sep 30, 2013 by meena.p

1 answer

The distance between field lens and eye lens in Ramsden eyepiece is $4 cm$. Then, the distance of the cross-wires from the eye lens is :

asked Sep 30, 2013 by meena.p

1 answer

A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and each one is equal to $\large\frac{3}{4}$ th the angle of prism. Then angle of deviation is :

asked Sep 30, 2013 by meena.p

2 answers

In an optical fibre, core and cladding were made with materials of refractive indices 1.5 and 1.414 respectively . To observe total internal reflection , what will be the range of incident angle with the axis of optical fibre?

asked Sep 30, 2013 by meena.p

1 answer

A sonometer wire has a length of $114$ cm, between two fixed ends. Where should two bridges be placed so as to divide the wire into three segments (in cm) whose fundamental frequencies are in the ratio 1 : 3 : 4 ?

asked Sep 30, 2013 by meena.p

2 answers

An organ pipe $P_1$, closed at one end and containing a gas of density $\rho _1 $ is vibrating in its first harmonic. Another organ pipe $P_2$, open at both ends and containing a gas of density $\rho_2$ is vibrating in its third harmonic . Both the pipes are in resonance with a given tuning fork. If the compressibility of gases is equal in both pipes, the ratio of the lengths of $P_1$ and $P_2$ is (assume the given gases to be monoatomic):

asked Sep 30, 2013 by meena.p

1 answer

Three rods AB,BC and BD made of the same material and having the same cross- section have been joined as shown in the figure. The ends A,C and D are held at temperatures of $20^{\circ},80^{\circ}$ and $80^{\circ}$ respectively. If each rod is of smme length, then the temperature at the junction B of the three rods is :

asked Sep 30, 2013 by meena.p

1 answer

3 moles of an ideal monatomic gas performs $ABCDA$ cyclic process as shown in figure below. The gas temperatures are $T_A=400\;K,T_B=800\;K,T_C=2400\;K,$ and $ T_D=1200\;K$. the work done by the gas is (approximately) $(R= 8.314\;J/mole K)$:

asked Sep 30, 2013 by meena.p

1 answer

An ideal gas expands isothermally from volume $V_1$ to volume $V_2$. It is then compressed to the original volume $V_1$ adiabatically.If $P_1,P_2$ and W represent the initial pressure, final pressure and the net work done by the gas respectively during the entire process, then:

asked Sep 30, 2013 by meena.p

1 answer

Three rods of equal lengths are joined to form an equilateral triangle ABC. D is the mid-point of AB. The coefficient of linear expansion is $\alpha _1$ for material of rod $AB$ and $\alpha _2$ for material of rods $AC$ and $BC$. If the distance $DC$ remains constant for small changes in temperature, then:

asked Sep 30, 2013 by meena.p

1 answer

A bimetallic strip is formed out of two identical strips, One of copper and the other of brass. The coefficients of linear expansion of the two metals are $ \alpha _C$ and $\alpha_{B}.$ On heating, the temperature of the strips increases by $\Delta T$ and the strip bend to from an arc of radius R. Then R is proportional to :

asked Sep 30, 2013 by meena.p

1 answer

Water from a tap emerges vertically downwards with initial velocity $4\;ms^{-1}$. The cross- sectional area of the tap is A. The flow is steady and pressure is constant throughout the stream of water. The distance h vertically below the tap, where the cross- sectional area of the stream becomes $\bigg(\large\frac{2}{3}\bigg)A,$ is $(g=10\; m/s^2)$:

asked Sep 30, 2013 by meena.p

1 answer

The excess pressure inside a spherical soap bubble of radius 1 cm is balanced by a column of oil $(Sp.gr=0.8),2$ mm high, the surface tension of the bubble is :

asked Sep 30, 2013 by meena.p

1 answer

Match the following:

asked Sep 30, 2013 by meena.p

1 answer

The displacements of two particles of same mass executing $SHM$ are represented by the equations $x_1=4 \sin \bigg[10t+\large\frac{\pi}{6}\bigg]$ and $x_2=5 \; \cos(\omega t)$. The value of $\omega$ for which the energy of both the particles remain same is :

asked Sep 30, 2013 by meena.p

1 answer

A launching vehicle carrying an artificial satellite of mass 'm'is set for launch on the surface of the earth of mass 'M' and radius 'R'. If the satellite is intended to move in a circular orbit of radius 7R, the minimum energy required to be spent by the launching vehicle on the satellite is : (Gravitational constant =G)

asked Sep 30, 2013 by meena.p

1 answer

A fly -wheel of mass 25 kg has a radius of $0.2\;m$. It is making 240 rpm. What is the torque necessary to bring to rest in 20 sec?

asked Sep 30, 2013 by meena.p

1 answer

The moment of inertia of a disc, of mass M and radius R, about an axis which is a tangent and to its diameter is :

asked Sep 30, 2013 by meena.p

1 answer

An object takes n times as much as to slide down a $45^{\circ}$ rough inclined plane as it takes to slide down a perfectly smooth inclined plane of the same inclination. The coefficient of kinetic friction between the object and the rough incline is given by :

asked Sep 30, 2013 by meena.p

1 answer

A ball falls from a height h and rebounds after striking the floor. The coefficient of restitution is $e$. The maximum distance covered before it comes to rest is :

asked Sep 30, 2013 by meena.p

1 answer

A bady of mass $M_1=4 kg$ moves at $ 5 \hat i$ m/s and another body of mass $m_2=2 kg$ moves at $10 \hat i$m/s. The kinetic energy of center of mass is :

asked Sep 30, 2013 by meena.p

1 answer

A bomb moving with velocity $ (40 \hat i+50 \hat j -25 \hat k)$m/sec explode into two pieces of mass ratio 1:4. After explosion the small piece moves away with velocity $(200 \hat i+70 \hat j+15 \hat k)$ m/sec. The velocity of larger piece after explosion is :

asked Sep 30, 2013 by meena.p

1 answer

A ball is falling from a height . When it reaches 10 m height from the ground its velocity is $V_0$. It collides with the ground and loses $50 \%$ of its energy and rises back to height of 10 m. Then the velocity $V_0$ is :

asked Sep 30, 2013 by meena.p

1 answer

An athlete completes one round of a circular track of radius R in 40 sec. What will be his displacement at the end of 2 min 20 seconds?

asked Sep 30, 2013 by meena.p

1 answer

A and B are two vectors f equal magnitude and $\theta$ is the angle between them. The angle between $\overrightarrow A$ or $\overrightarrow B$ with their resultant is :

asked Sep 29, 2013 by meena.p

1 answer

If the force is given by $F= at +bt^2$ with t as time. The dimensions of a and b are :

asked Sep 29, 2013 by meena.p

1 answer

The sensitivity of a galvanometer is $60$ divisions /Amp. When a shunt is used, its sensitivity become 10 divisions/Amp. If the galvanometer is of resistance $20 \Omega$, the value of shunt used is :

asked Sep 24, 2013 by meena.p

1 answer

A constant voltage of $25\; V$ is applied to a series $L-R$ circuit at $t=0$, by closing a switch. What is the potential difference across the resistor and the inductor at time $t=0$?

asked Sep 24, 2013 by meena.p

1 answer

Match the following and find the correct pairs:

asked Sep 24, 2013 by meena.p

1 answer

The thermo e.m of a hypothetical thermocouple varies with the temperature $\theta$ of hot junction as $E= a \theta + b \theta^2$ in volts, where the ratio $a/b$ is $700^{\circ}C$. If the cold junction is kept at $0^{\circ}C,$ then the neutral temperature is :

asked Sep 24, 2013 by meena.p

1 answer

Int he circuit shown below, the ammeter reading is zero. Then the value of the resistance $R$ is :

asked Sep 24, 2013 by meena.p

1 answer

The electric current i in the circuit shown is :

asked Sep 24, 2013 by meena.p

1 answer

Two identical condenser M and N are connected in series with a battery. The space between the plates of M is completely filled with a dielectric medium of dielectric constant 8 and a copper plate of thickness $\large\frac{d}{2}$ is introduced between the plates of N. (d is the distance between the plates). Then potential differences across M and N are, respectively , in the ratio:

asked Sep 24, 2013 by meena.p

1 answer

A fully charged capacitor has a capacitance $'C'$. It is discharged through a small coil resistance wire, embedded in a block of specific heat $'s'$ and mass $'m'$ under thermally isolated conditions. If the temperature of the block is raised by $'\Delta T$, the potential difference $V$ across the capacitor initially is :

asked Sep 24, 2013 by meena.p

1 answer

Some physical quantities are given in the List I and the related units are given in the List II.Match the correct pairs in the list:

asked Sep 24, 2013 by meena.p

1 answer

If a bar magnet of pole strength $m$ and magnetic moment M is cut equally 5 times parallel to its axis and again 3 times perpendicular to its axis, then the pole strength and magnetic moment of each piece are respectively:

asked Sep 24, 2013 by meena.p

1 answer

In the Young's double slit experiment, the resultant intensity at a point on the screen is $75 \%$ of the maximum intensity of the bright fringe. Then the phase difference between the two interfering rays at that point is :

asked Sep 24, 2013 by meena.p

1 answer

A ray of light refracts from medium 1 into a thin layer of medium 2, crosses the layer and is incident at the critical angle on the interface between the medium 2 and 3 as shown in figure. If the angle of incidence of ray is $\theta$, the value of $\theta$ is :

asked Sep 24, 2013 by meena.p

3 answers

Which of the following statement are $true$ in the context of a Compound Microscope?

asked Sep 24, 2013 by meena.p

1 answer

The focal length of a lens of dispersive power $0.45$ which should be placed in contact with a convex lens of focal length $84\;cm$ and dispersive power $0.21$ to make the achromatic combination from the two lenses, in cm is :

asked Sep 24, 2013 by meena.p

2 answers

Two uniform stretched string A and B, made of steel , are vibrating under the same tension. If the first overtone of A is equal to the second overtone of B and if the radius of A is twice that of B, the ratio of the lengths of the strings is :

asked Sep 24, 2013 by meena.p

1 answer

The wavelengths of two sound notes in air are $\large\frac{40}{195}\;$$m$ and $\large\frac{40}{193}\;$$m$. Each note produces 9 beats per second separately with a third note of fixed frequency. The velocity of sound in air in m/s is:

asked Sep 24, 2013 by meena.p

1 answer

Two slabs A and B of different materials but of the same thickness are joined and to end to form a composite slab. The thermal conductivities of A and B are $'k_1'$ and $'k_2$ respectively. A steady temperature distance of $12^{\circ}$ is maintained across the composite slab. If $k_1=\large\frac{k_2}{2}$, the temperature difference across slab A is

asked Sep 24, 2013 by meena.p

1 answer

During an adiabatic process, the pressure of a gas is proportional to the cube of its temperature. The value of $C_p/C_v$ for that gas is :

asked Sep 24, 2013 by meena.p

1 answer

A reversible engine converts one-sixth of the heat supplied into work. When the temperature of the sink is reduced by $62^{\circ}C$, the efficiency of the engine is doubled. The temperatures of the source and skin are:

asked Sep 24, 2013 by meena.p

1 answer

An insulated cylindrical vessel filled with an insulated piston of negligible weight and negligible thickness at the mid point of the vessel. The cylinder contains a gas at $0^{\circ}C$. When the gas is heated to $100^{\circ}$, the piston moves through a length of $5 \;cm$. Length of the cylindrical vessel is cm is :

asked Sep 24, 2013 by meena.p

1 answer

A non-conducting body floats in a liquid at $20^{\circ}C$ with $\large\frac{2}{3}$ of its volume immersed in the liquid. When liquid temperature is increased to $100^{\circ}C,\large\frac{3}{4}$ of body's volume is immersed in the liquid . Then the coefficient of real expansion of the liquid is (neglecting the expansion of the liquid):

asked Sep 24, 2013 by meena.p

1 answer

A large open tank has two holes in the wall. One is a square hole of side $'L'$ at a depth $'y'$ from the top and the other is a circular hole of radius R at a depth $'4y'$ from the top. When the tank is completely filled with water, the quantities of water flowing out per second from the two holes are the same. Then value of R is :

asked Sep 24, 2013 by meena.p

1 answer

If two soap bubbles of different radii are connected by a tube, then :

asked Sep 24, 2013 by meena.p

1 answer

Two blocks of masses $1\;kg$ and $2\;kg$ are connected by are connected by a metal wire going over a smooth pulley. The breaking stress of metal is $\large\frac{40}{3 \pi}$$\times 10^6\;Nm^{-2}$.What should be the minimum radius of wire used if it should not break? $(g=10\;m/s^{-2})$

asked Sep 24, 2013 by meena.p

2 answers

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