Recent questions in Physics

A small square loop of wire of side i is placed inside a large square loop of slide $L( L >>1)$. If the loops are coplanar and there centers coinside. the mutual induction of the system is directly proportional to :

asked Oct 29, 2013 by meena.p

1 answer

A rectangular loop of length l and breadth b is placed at distance of x from infinitely long wire carrying current i such that the direction of current is parallel to breadth. If the loop moves away from the current wire in a direction perpendicular to it with a velocity v, the magnitude of the emf in the loop is : ($\mu_o$= permeability of free space)

asked Oct 29, 2013 by meena.p

1 answer

When positively charged particle enters a uniform magnetic field with uniform velocity, its trajectory can be :

asked Oct 29, 2013 by meena.p

1 answer

If the cold junction is held at $0^{\circ}$, the same thermo emf V of a thermocouple varies as $V= 10 \times 10^{-6} t -\large\frac{1}{40} \times 10^{-6}t^2$, Where t is the temperature of the hot junction in $^{\circ}C$. The neutral temperature and the maximum value of thermo emf are respectively:

asked Oct 29, 2013 by meena.p

1 answer

Twelve cells, each having emf E volts are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter , an external resistance R ohms and a two- cell battery (two cells of the same type used earlier , connected perfectly in series). The current in the circuit when the 12 - cell battery and 2-cell battery aid each other is 3A and is 2A when they oppose each other . Then, the number of cells in 12 -cell battery that are connected wrongly is :

asked Oct 29, 2013 by meena.p

2 answers

One end of each of a resistance r capacitor C and resistance 2r are connected together. The other ends are respectively connected to the positive terminals of batteries, P, Q, R having respectively emf's E,E and 2E. The negative terminals of the batteries are then connected together. In this circuit, with steady current the potential drop across the capacitor is :

asked Oct 29, 2013 by meena.p

1 answer

Along the X-axis, three charges $\large\frac{q}{2},-q$ and $\large\frac{q}{2}$ are placed at $x=0,x= a$ and $x=2a$ respectively. The resultant electric potential at $x=a+r$ if ( a << r) is : $( \varepsilon_0$ is the permittivity of free space)

asked Oct 29, 2013 by meena.p

1 answer

The bob of simple pendulum is hanging vertically down from a fixed identical bob by means of a string of length l. If both bobs are charged with a charge q each , time period of the pendulum is : (ignore the radii of the bobs)

asked Oct 29, 2013 by meena.p

1 answer

Two short managers AB and CD are in the X-Y plane and are parallel to X-axis and coordinate of their centers respectively are (0,2) and (2,0). Line joining the north- south poles of CD is opposite to that of AB and lies along the positive X-axis. The resultant field induction due to AB and CD at a point P(2,2) is $100 \times 10^{-7}\;T$. When the poles of the magnet CD are reversed, the resultant field induction is $50 \times 10^{-7}T$. The value of magnetic moments of AB and CD (in $AM^2$) are :

asked Oct 29, 2013 by meena.p

1 answer

The effect due to uniform magnetic field on a freely suspended magnetic needle is as follows :

asked Oct 29, 2013 by meena.p

1 answer

In Young's double slit experiment, first slit has width four of the second slit. the ratio of the maximum intensity to the minimum intensity in the interference fringe system is :

asked Oct 29, 2013 by meena.p

1 answer

Match the appropriate pairs from List I and List II

asked Oct 29, 2013 by meena.p

1 answer

Dispersive power depends on the following :

asked Oct 29, 2013 by meena.p

1 answer

The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex lenses. The two pieces are glued such that the convex surface touch each other. If this combination lens is immersed in water(refractive index=4/3), its focal length (in cm) is :

asked Oct 29, 2013 by meena.p

1 answer

An observer is standing 500 m away from a vertical hill, a police van sounding a siren of frequency 1000 Hz moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is 970 Hz. the frequency of the sound heard after reflection from the hill (in Hz) is about, (velocity of sound =$330\;ms^{-1}$):

asked Oct 29, 2013 by meena.p

1 answer

Two string A and b of lengths, $L_a=80\;cm$ and $L_B=x\;cm$ respectively are used separately in a sonometer. The ratio of their densities $(d_A/d_B)$ is $0.81$ The diameter of B is one -half that of A. If the string have the same tension and fundamental frequency the value of x is :

asked Oct 29, 2013 by meena.p

1 answer

Two solid spheres A and B made of the same material have radii $r_A$ and $r_B$ respectively. Both the sphere are cooled from the same temperature under the conditions valid for Newton's law of cooling. The ratio of the rate of change of temperature of A and B is :

asked Oct 29, 2013 by meena.p

1 answer

The cyclic process ABCD is shown below in the given P.V diagram. In the following answers the one that represents the same process as in the P-V diagram

asked Oct 29, 2013 by meena.p

1 answer

A given mass of a gas is compressed isothermally until its pressure is doubled. It is then allowed to expand adiabatically until its original volume is restored and its pressure is then found to be 0.75 of its initial pressure. The ratio of the specific heats of the gas is approximately :

asked Oct 29, 2013 by meena.p

1 answer

The temperature of a thin uniform circular disc, of one meter diameter is increased by $10^{\circ}C$. The percentage increase in moment of inertia of the disc about an axis passing through its center and perpendicular to the circular face: (linear coefficient of expansion $=11 \times 10^{-6}/^{\circ}C)$

asked Oct 29, 2013 by meena.p

1 answer

Two block of masses 1 kg and 2 kg are connected by a metal wire going over a smooth in figure. The breaking stress of the metal is $2 \times 10^{9} \;N/m^2$. What should be the minimum radius of the wire used if it is not to break? Take $g=10\;ms^2$

asked Oct 29, 2013 by meena.p

1 answer

An air bubble of radius 1 cm rises from the bottom portion through a liquid of density $1.5 g/cc$ at a constant speed of $0.250 \;cm^{-1}$.If the density of air is neglected, the coefficient of viscosity of the liquid is approximately, (In pas):

asked Oct 29, 2013 by meena.p

1 answer

Two soap bubbles combine to form a single bubble. In this process, the change in volume and surface area are respectively V and A. If P is the atmospheric pressure, and T is the surface tension of the soap solution, the following relation is true.

asked Oct 29, 2013 by meena.p

1 answer

Assertion (a) : Ductile metals are used to prepare thin wires. Reason (R) : In the stress - strain curve of ductile metals, the length between the points representing elastic limit and breaking point is very small.

asked Oct 29, 2013 by meena.p

1 answer

To the free end of spring hanging from a rigid support, a block of mass m is hung and slowly allowed to come to its equilibrium position. Then stretching in the spring is d. If the same block is attached to the same spring and allowed to fall suddenly, the amount of stretching is : (force constant , k)

asked Oct 28, 2013 by meena.p

1 answer

Assertion (a) : A particle of mass m dropped into a hole made along the diameter of the earth from one end to another and possess simple harmonic mention. Reason (R) : Gravitational force between any two particles is inversely proportional to the square of the distance between them.

asked Oct 28, 2013 by meena.p

1 answer

Assume the earths orbit around the sun as circular and the distance between their centers as D. Mass of the earth is M and its radius is R. If earth has an angular velocity $\omega _0$ with respect to its center and $\omega$with respect to the center of the sun, the total kinetic energy of earth is :

asked Oct 28, 2013 by meena.p

1 answer

A uniform rod of length 8a and mass 6m lies on a smooth horizontal surface. Two points masses m and 2m moving in the same plane with speed 2v and v respectively strikes the rod perpendicularly at distances a and 2a from the mid point of the rod in the opposite directions and stick to the rod. The angular velocity of the system immediately after the collision is :

asked Oct 28, 2013 by meena.p

1 answer

When the angle of inclination of an inclined plane is 0, an object slides down with uniform velocity. If the same object is pushed with a initial velocity u on the same inclined plane; it goes up the plane and stops at a certain distance on the plane. Thereafter the body:

asked Oct 28, 2013 by meena.p

1 answer

For a system to follow the law of conservation of linear momentum during a collision the condition is :

asked Oct 28, 2013 by meena.p

1 answer

A man of 50kg is standing at one end on a boat of length 25 m and mass $200\;kg$. If he starts running and when he reaches the other end, he has a velocity $2\;ms^{-1}$ with respect to boat The final velocity of the boat is : (in $ms^{-1}$)

asked Oct 28, 2013 by meena.p

1 answer

A bullet of mass 10g id fired horizontally with a velocity $1000 ms^{-1}$ from a rifle situated at a height 50 m above the ground. If the bullet reaches the ground with a velocity $500 ms^{-1}$, the work done against air resistance in the trajectory of the bullet is : $ (g=10\;ms^{-2})$

asked Oct 28, 2013 by meena.p

1 answer

A motor is used to deliver water at a certain rate through a given horizontal pipe. To deliver n-times the water through the same pipe in the same time the power of the motor must be increased as follows :

asked Oct 28, 2013 by meena.p

1 answer

A body is projected from the earth at angle $30^{\circ}$ with the horizontal with some initial velocity. If its range is 20 m, the maximum height reached by it is : (in meters)

asked Oct 28, 2013 by meena.p

1 answer

A man standing on a road has to hold his umbrella at $30^{\circ}$ with the vertical to keep the rain away. He throws the umbrella and starts running at 10 km/h. He finds that raindrops are hitting his head vertically. The actual speed of raindrops is :

asked Oct 28, 2013 by meena.p

1 answer

If G.R.I and I denote capacity, resistance, inductance and electric current respectively, the quantities having the same dimensions of time are : $(1)CR ,\; (2)\;\large\frac{L}{R},\;(3)\;\sqrt {LC}, \;(4)\;LI^2$

asked Oct 28, 2013 by meena.p

1 answer

In an n-type semiconductor, the fermi energy level lies

asked Oct 23, 2013 by meena.p

1 answer

In Sun, the important source of energy is

asked Oct 23, 2013 by meena.p

1 answer

The work function of the nickel is $5 \;eV$. When a light of wavelength 2000 A falls on it, it emits photo electrons in the circuit. Then the potential difference necessary to stop the fastest electrons emitted is (given $h= 6.67 \times 10^{-34}\;J-s$)

asked Oct 23, 2013 by meena.p

1 answer

an electron beam travels with a velocity of $1.6 \times 10^{7}\;ms^{-1}$ perpendicularly to magnetic field of intensity 0.1 T. The radius of the path of electron beam $(m_e=9 \times 10^{-31}kg)$

asked Oct 23, 2013 by meena.p

1 answer

The natural frequency of an $I-C$ circuit is $1,25,000$ cycle/s. Then the capacitor C is replaced by another capacitor with a dielectric medium of dielectric constant by $25 \;kHz$. The value of K is

asked Oct 23, 2013 by meena.p

1 answer

Two wires A and B are of lengths 40 cm and 30 cm. A is bent into a circle of radius r and B into an arc of radius r. A current $t_1$ is passed through A and $t_2$ through B. To have the same magnetic induction at the center, the ratio of $t_1:t_2$ is

asked Oct 23, 2013 by meena.p

1 answer

Temperature of cold junction in a thermo couple is $10^{\circ}$ and neutral temperature is $270^{\circ}$, then the temperature of inversion is

asked Oct 23, 2013 by meena.p

1 answer

An aluminium (resistivity $\rho=2.2 \times 10^{-8} \Omega m)$ wire of a diameter $1.4 \;mm$ is used to make a $4 \Omega$ resistor. The length of the wire is

asked Oct 23, 2013 by meena.p

1 answer

Two unit negative charges are placed on a straight line. A positive charge q is placed exactly at the mid point between these unit charges. If the system of these three charges is in equilibrium, the value of (q in C) is

asked Oct 23, 2013 by meena.p

1 answer

In a metre bridge experiment, the ratio of the left gap resistance to right gap resistance is $2:3$, the balance point from left is

asked Oct 23, 2013 by meena.p

1 answer

Along the x-axis, three charges $\large\frac{q}{2},$$-q$ and $\large\frac{q}{2}$ are placed at $x=0,x=a$ and $x=2a$ respectively. The resultant electric potential at a point P located at a distance r from the charge -q( a << r) is ($ \varepsilon _0 $ is the permittivity of free space)

asked Oct 23, 2013 by meena.p

1 answer

A bar magnet of magnetic moment M and moment of inertia I is freely suspended such that the magnetic axial line in the direction of magnetic meridian. If the magnet is displaced by a very small angle ($ \theta$), the angular acceleration is (Magnetic induction of earth's horizontal field$=B_H$)

asked Oct 23, 2013 by meena.p

1 answer

A bar-magnet of moment of inertia $49 \times 10^{-2}$ vibrates in a magnetic field of induction $0.5 \times 10^{-4}T.$ The time period of vibration is $8.8 \;s$. The magnetic moment of the bar magnet is

asked Oct 22, 2013 by meena.p

1 answer

In Huygens eyepiece

asked Oct 22, 2013 by meena.p

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