A galvanmeter has a coil of resistance \(200 \Omega\) with a full scale deflection at \(20 \mu \mathrm{A}\). The value of resistance to be added to use it as an ammeter of range \((0-20) \mathrm{mA}\) is _______.

A rigid wire consists of a semicircular portion of radius \(R\) and two straight sections. The wire is partially immerged in a perpendicular magnetic field \(B=B_0\ {j}\) as shown in figure. The magnetic force on the wire if it has a current \(i\) is _______.

Drift speed of electrons, when \(1.5\, A\) of current flows in a copper wire of cross section \(5\, mm^2\), is \(v\). If the electron density in copper is \(9 \times 10^{28}\, m^3\) the value of \(v\) in \(mm/s\) is close to (Take charge of electron to be \(= 1.6 \times 10^{-19}\, C\))

A Copper \((Cu)\) rod of length \(25\, {cm}\) and cross- sectional area \(3\, {mm}^{2}\) is joined with a similar Aluminium \((Al)\) rod as shown in figure. Find the resistance of the combination between the ends \(A\) and \(B\) (in \({m} \Omega\)) (Take Resistivity of Copper \(=1.7 \times 10^{-8}\, \Omega \,{m}\), Resistivity of Aluminium \(=2.6 \times 10^{-8}\, \Omega \,{m}\) )

A capacitor has air as dielectric medium and two conducting plates of area \(12 \mathrm{~cm}^2\) and they are \(0.6 \mathrm{~cm}\) apart. When a slab of dielectric having area \(12 \mathrm{~cm}^2\) and \(0.6 \mathrm{~cm}\) thickness is inserted between the plates, one of the conducting plates has to be moved by \(0.2 \mathrm{~cm}\) to keep the capacitance same as in previous case. The dielectric constant of the slab is _______. (Given \(\left.\epsilon_0=8.834 \times 10^{-12} \mathrm{~F} / \mathrm{m}\right)\)

In the circuit diagrams \((A, B, C\) and \(D\)) shown below, \(R\) is a high resistance and \(S\) is a resistance of the order of galvanometer resistance \(G\). The correct circuit, corresponding to the half deflection method for finding the resistance and figure of merit of the galvanometer, is the circuit labelled as

The electric field in a region is given by \(\vec E = \frac{3}{5}{E_0}\hat i + \frac{4}{5}{E_0}\hat j\) and \(E_0 = 2\times10^3\, N/C\). Then, the flux of this field through a rectangular surface of area \(0.2\, m^2\) parallel to the \(y-z\) plane is......\(\frac{{N - {m^2}}}{C}\)

Two masses m and 2m are connected by a light string going over a pulley (disc) of mass 30m with radius r = 0.1 m. The pulley is mounted in a vertical plane and it is free to rotate about its axis. The 2m mass is released from rest and its speed when it has descended through a height of 3.6 m is __________ m/s. (Assume string does not slip and \( g=10 m/s^{2} \))

The density of a material in \(SI\, units\) is \(128\, kg\, m^{-3}\). In certain units in which the unit of length is \(25\, cm\) and the unit of mass \(50\, g\), the numerical value of density of the material is

The activity of a radioactive material is \(2.56 \times 10^{-3} \,Ci\). If the half life of the material is \(5\) days, after how many days the activity will become \(2 \times 10^{-5} \,Ci\) ?