The source of time varying magnetic field may be \((A)\) a permanent magnet \((B)\) an electric field changing linearly with time \((C)\) direct current \((D)\) a decelerating charge particle \((E)\) an antenna fed with a digital signal Choose the correct answer from the options given below:

Two point charges \(A\) and \(B\) of magnitude \(+8 \times 10^{-6}\,C\) and \(-8 \times 10^{-6}\,C\) respectively are placed at a distance \(d\) apart. The electric field at the middle point \(O\) between the charges is \(6.4 \times 10^{4}\,NC ^{-1}\). The distance ' \(d\) ' between the point charges \(A\) and \(B\) is..............\(m\)

A telescope has an objective lens of focal length \(150\,\,cm\) and an eyepiece of focal length \(5 \,\,cm.\) If a \(50\,\,m\) tall tower at a distance of \(1\,\,km\) is observed through this telescope in normal setting, the angle formed by the image of the tower is \(\theta \), then \(\theta \) is close to.....\(^o\)

In a meter bridge, the wire of length \(1\, m\) has a nonuniform cross-section such that, the variation \(\frac{{dR}}{{d\ell }}\) of its resistance \(R\) with length \(\ell \) is \(\frac{{dR}}{{d\ell }} \propto \frac{1}{{\sqrt \ell  }}\) Two equal resistances are connected as shown in the figure. The galvanometer has zero deflection when the jockey is at point \(P\). What is the length \(AP\) ? ................ \(m\)

A conducting loop of radius \(\frac{10}{\sqrt{\pi}}\,cm\) is placed perpendicular to a uniform magnetic field of \(0.5\,T\). The magnetic field is decreased to \(zero\) in \(0.5\,s\) at a steady rate. The induced emf in the circular loop at \(0.25\,s\) is:

The stream of a river is flowing with a speed of \(2\,km/h.\) A swimmer can swim at a speed of \(4\,km/h.\) ....... \(^o\) should be the direction of the swimmer with respect to the flow of the river to cross the river straight .

In the circuit shown here, the voltage across \(L\) and \(C\) are respectively \(300\, V\) and \(400\, V\). The voltage \(E\) of the ac source is......\(Volt\)

A block is fastened to a horizontal spring. The block is pulled to a distance \(x =10\,cm\) from its equilibrium position (at \(x =0\) ) on a frictionless surface from rest. The energy of the block at \(x =5\) \(cm\) is \(0.25\,J\). The spring constant of the spring is \(.........Nm ^{-1}\)

The motion of a simple pendulum excuting \(S.H.M\). is represented by following equation. \(Y = A \sin (\pi t +\phi)\), where time is measured in \(second\). The length of pendulum is .............\(cm\)

The rain drop of mass \(1\) g, starts with zero velocity from a height of \(1\) km. It hits the ground with a speed of \(5\) m/s. The work done by the unknown resistive force is _______ J. (take \(g = 10\) m/s\(^2\))

A plane electromagnetic wave having a frequency \(n = 23.9\, GHz\) propagates along the positive \(z-\) direction in free space. The peak value of the electric field is \(60\, V/m\). Which among the following is the acceptable magnetic field component in the electromagnetic wave?