In the potentiometer, when the cell in the secondary circuit is shunted with 4 \(\Omega\) resistance, the balance is obtained at the length 120 cm of wire. Now when the same cell is shunted with 12 \(\Omega\) resistance, the balance is shifted to a length of 180 cm. The internal resistance of cell is ___________ \(\Omega\).

Two p-n junction diodes \(D _1\) and \(D _2\) are connected as shown in figure. A and B are input signals and C is the output. The given circuit will function as a ___________.

The following observations were taken for determining surface tension \(T\) of water by capillary method: diameter of capillary, \(D= 1.25 \times 10^{-2}\; m\) rise of water, \(h=1.45 \times 10^{-2}\; m \)  Using \(g= 9.80 \;m/s^2\) and the simplified relation \(T = \frac{{rhg}}{2}\times 10^3 N/m\) , the possible error in surface tension is ........... \(\%\)

The bob of a simple pendulum has mass \(2\,g\) and a charge of \(5.0\,\mu C\). It is at rest in a uniform horizontal electric field of intensity \(2000\,\frac{V}{m}\). At equilibrium, the angle that the pendulum makes with the vertical is (take \(g = 10\,\frac{m}{{{s^2}}}\))

In the circuit shown in the figure, the ratio of the quality factor and the band width is \(.............\) s.

Given below are two statement: one is labelled as Assertion \(A\) and the other is labelled as Reason \(R.\) Assertion \(A:\) \(EM\) waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology. Reason \(R\) : Infrared \(EM\) waves are more energetic than microwaves, (used in Radar) In the light of given statements, choose the correct answer from the options given below:

Truth table for the given circuit will be

A metal exposed to light of wavelength \(800\,nm\) and emits photoelectrons with a certain kinetic energy. The maximum kinetic energy of photo-electron doubles when light of wavelength \(500\, nm\) is used. The work function of the metal is \(...eV\) (Take \(hc =1230 \,eV - nm\) ).

The total charge on the system of capacitance \(C _{1}=1\,\mu F , C _{2}=2\,\mu F , C _{3}=4\,\mu F\) and \(C _{4}=3\,\mu F\) connected in parallel is \(......\mu C\) (Assume a battery of \(20\,V\) is connected to the combination)