Physics Test-11...

The electric field of a plane electromagnetic wave varies with time of amplitude \(2 \mathrm{~V} \mathrm{~m}^{-1}\) propagating along z-axis. The average energy density of the magnetic field is ( in \(\left.\mathrm{Jm}^{-3}\right)\) :

A body of \(5 \mathrm{~kg}\) is moving with a velocity of \(20 \mathrm{~m} / \mathrm{sec}\). If a force of \(100 \mathrm{~N}\) is applied on it for 10 sec in the same direction as its velocity, what will now be the velocity of the body?

In hydrogen atom, the electron makes \(6.6 \times 10^{15}\) revolutions per second around the nucleus in an orbit of radius \(0.5 \times 10^{-10} \mathrm{~m}\). It is equivalent to a current nearly:

The rest mass of the photon is:

The magnetic flux \(\phi\) (in weber) linked with a coil of resistance \(10 \Omega\) varies with time \(t\) (in second) as \(\phi=8 t^{2}-4 t+1\). The current induced in the coil at \(t=0.1 \mathrm{sec}\) is:

In a compound microscope, the objective and the eyepiece have focal lengths of \(5 \mathrm{~cm}\) and \(9.5\) \(\mathrm{cm}\), respectively, and both are kept at a distance of \(20 \mathrm{~cm}\). If the final image is formed at the least distance of \(25 \mathrm{~cm}\) from the eyepiece, find the total magnification.

The momentum of a body is \(850.00 \mathrm{~kg} \mathrm{~m} / \mathrm{sec}\) and its mass is \(40.00 \mathrm{~kg}\). Find its kinetic energy.

A balloon rises from rest with a constant acceleration \(\frac{g}{8}\). A stone is released from it when it has risen to height \(h\). The time taken by the stone to reach the ground is:

The magnetic field of an electromagnetic wave is given by, \(B_{y}=\left(3 \times 10^{-7} \mathrm{~T}\right) \sin \left(10^{3} x+6.29 \times 10^{12} t\right)\)

Where \(x, t\) are in S.I. units. The wavelength of the electromagnetic wave is:

If the electrical conductivity of a semiconductor increases when electromagnetic radiation of a wavelength shorter than \(2480 \mathrm{~nm}\) is incident on it. What is the band gap (in eV) for the semiconductor?

In an electromagnetic wave, the magnitude of electric and magnetic fields are \(100 \mathrm{~V} / \mathrm{m}\) and \(0.265 \mathrm{~A} / \mathrm{m}\). The maximum energy flow is:

A source emitting wavelengths \(480 \mathrm{~nm}\) and \(600 \mathrm{~nm}\) is used in Young's Double Slit Experiment. The separation between the slits is \(0.25 \mathrm{~mm}\). The interference is observed \(1.5 \mathrm{~m}\) away from the slits. The linear separation between the first maxima of the two wavelengths is:

Two small charged spheres \(A\) and \(B\) have charges \(10 \mu C\) and \(40 \mu C\), respectively, and are held at a separation of \(90 \mathrm{~cm}\) from each other. At what distance from \(A\) would the electric intensity be zero?

Three thermally radiating carbon black coated discs \(A, B\) and \(C\) with radii \(2 \mathrm{~m}, 4 \mathrm{~m}\) and \(6 \mathrm{~m}\) have maximum intensity wavelengths \(300 \mathrm{~nm}, 400 \mathrm{~nm}\) and \(500 \mathrm{~nm}\), respectively. If the powers radiated by them are \(Q_{A}, Q_{B}\) and \(Q_{C}\), respectively, then:

The Young's modulus of the material of a wire is \(6 \times 10^{12} \mathrm{~N} / \mathrm{m}^{2}\) and there is no transverse in it, then its modulus of rigidity will be: