A block of mass \(M\) placed inside a box descends vertically with acceleration \('a'\). The block exerts a force equal to one-fourth of its weight on the floor of the box. The value of \('a'\) will be .............

In the given circuit all resistances are of value \(R\,ohm\) each. The equivalent resistance between \(A\) and \(B\) is 

A circular coil having \(200\) turns, \(2.5 \times 10^{-4} \mathrm{~m}^2\) area and carrying \(100 \mu \mathrm{A}\) current is placed in a uniform magnetic field of \(1 \mathrm{~T}\). Initially the magnetic dipole moment \((\vec{M})\) was directed along \(\vec{B}\). Amount of work, required to rotate the coil through \(90^{\circ}\) from its initial orientation such that \(\overrightarrow{\mathrm{M}}\) becomes perpendicular to \(\vec{B}\) is _______ \(\mu \mathrm{J}\).

A potential barrier of \(0.4 \,V\) exists across a p-n junction. An electron enters the junction from the \(n\)-side with a speed of \(6.0 \times 10^{5} \,ms ^{-1}\). The speed with which electron enters the \(p\) side will be \(\frac{x}{3} \times 10^{5} \,ms ^{-1}\) the value of \(x\) is .............. (Given mass of electron \(=9 \times 10^{-31} \,kg\), charge on electron \(=1.6 \times 10^{-19} \,C\).)

In a hypothetical fission reaction \({ }_{92} \mathrm{X}^{236} \rightarrow{ }_{56} \mathrm{Y}^{141}+{ }_{36} \mathrm{Z}^{92}+3 \mathrm{R}\) The identity of emitted particles \((R)\) is _______.

A single turn current loop in the shape of a right angle triangle with sides \(5\,cm , 12\,cm , 13\,cm\) is carrying a current of \(2\,A\). The loop is in a uniform magnetic field of magnitude \(0.75\,T\) whose direction is parallel to the current in the \(13\,cm\) side of the loop. The magnitude of the magnetic force on the \(5\,cm\) side will be \(\frac{ x }{130}\,N\). The value of \(x\) is \(..........\)

Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01 cm and 18.25 cm. The relative error in the measurement of average length of the rod is :

If minimum possible work is done by a refrigerator in converting \(100\; grams\) of water at \(0^{\circ} C\) to ice, how much heat (in calories) is released to the surrounding at temperature \(27^{\circ} C\) (Latent heat of ice \(=80 Cal / gram\) ) to the nearest integer?

The diffraction pattern of a light of wavelength \(400\) \(\mathrm{nm}\) diffracting from a slit of width \(0.2 \mathrm{~mm}\) is focused on the focal plane of a convex lens of focal length \(100 \mathrm{~cm}\). The width of the \(1^{\text {st }}\) secondary maxima will be _______.

In a Young's double slit experiment, \(16\) fringes are observed in a certain segment of the screen when light of wavelength \(700 \,nm\) is used. If the wavelength of light is changed to \(400 \,nm\), the number of fringes observed in the same segment of the screen would be........

An unknown metal of mass \(192\, g\) heated to a temperature of \(100\,^oC\) was immersed into a brass calorimeter of mass \(128\, g\) containing \(240\, g\) of water at a temperature of \(8.4\,^oC\). Calculate the specific heat of the unknown metal if water temperature stabilizes at \(21.5\,^oC\). (Specific heat of brass is \(394\, J\, kg^{-1}\, K^{-1}\)) ......... \(J\, kg^{-1}\, K^{-1}\)