A tuning fork vibrates with frequency \(256\, Hz\) and gives one beat per second with the third normal mode of vibration of an open pipe . What is the length of the pipe? ... \(cm\) (Speed of sound of air is \(340\, ms^{-1}\))

A small square loop of side \('a'\) and one turn is placed inside a larger square loop of side \({b}\) and one turn \((b \gg a)\). The two loops are coplanar with thei centres coinciding. If a current \(I\) is passed in the square loop of side \('b',\) then the coefficient of mutual inductance between the two loops is

Every planet revolves around the sun in an elliptical orbit : \(A.\) The force acting on a planet is inversely proportional to square of distance from sun. \(B.\) Force acting on planet is inversely proportional to product of the masses of the planet and the sun \(C.\) The centripetal force acting on the planet is directed away from the sun. \(D.\) The square of time period of revolution of planet around sun is directly proportional to cube of semi-major axis of elliptical orbit. Choose the correct answer from the options given below :

In an electric circuit, a cell of certain emf provides a potential difference of \(1.25\, {V}\) across a load resistance of \(5\, \Omega .\) However, it provides a potential difference of \(1\, {V}\) across a load resistance of \(2\, \Omega\). The \(emf\) of the cell is given by \(\frac{x}{10} v\). Then the value of \(x\) is ..... .

A batsman hits back a ball of mass \(0.4 \; kg\) straight in the direction of the bowler without changing its initial speed of \(15 \; ms ^{-1}\). The impulse imparted to the ball is \(\dots \; Ns\)

The box of a pin hole camera, of length \(L\), has a hole of radius \(a\). It is assumed that when the hole is illuminated by a parallel beam of light of wavelength \(\lambda\), the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size ( say \(b_{min}\)) when

Two identical cells, when connected either in parallel or in series gives same current in an external resistance \(5\,\Omega\). The internal resistance of each cell will be \(.............\,\Omega\).

An electric toaster has resistance of \(60\  \Omega\) at room temperature \(\left(27^{\circ} \mathrm{C}\right)\). The toaster is connected to a \(220 \mathrm{~V}\) supply. If the current flowing through it reaches \(2.75 \mathrm{~A}\), the temperature attained by toaster is around _______. (if \(\alpha=2 \times 10^{-4} /{ }^{\circ} \mathrm{C}\) )

The pressure \(( P )\) and temperature \(( T )\) relationship of an ideal gas obeys the equation \(PT ^2=\) constant. The volume expansion coefficient of the gas will be:

The current required to be passed through a solenoid of \(15\,cm\) length and 60 turns in order to demagnetise a bar magnet of magnetic intensity \(2.4 \times 10^3\,Am ^{-1}\) is \(.........A\).