Class 12th

A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure. Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field $\stackrel{}{}$ pointing into the page. An external agent pulls the bar to the left at a constant speed v.

The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is:

For the given circuit, comment on the type of transformer used.

Find out the surface charge density at the intersection of point x = 3 m plane and x-axis, in the region of uniform line charge of 8 nC/m lying along the z-axis in free space.

A bar magnet of length 14 cm is placed in the magnetic meridian with its north pole pointing towards the geographic north pole. A neutral point is obtained at a distance of 18 cm from the centre of the magnet. If BH = 0.4G, the magnetic moment of the magnet is 1G = 10^-4T

The stopping potential in the context of photoelectric depends on the following property of incident electromagnetic radiation:

The refractive index of converging lens is 1.4. What will be the focal length of this if it is placed in a medium of same refractive index? Assume the radii of curvature of the faces of lens are R₁ and R₂ respectively.

The de Broglie wavelength associated with an electron and a proton were calculated by accelerating them through same potential of 100V. What should be the ratio of their wavelengths? (m? = 1.00727u, m? = 0.00055u)

The half-life of Au¹⁹⁸ is 2.7 days. The activity of 1.50 mg of Au¹⁹⁸ if its atomic weight is 198 g mol⁻¹ is, (Nₐ = 6*10²³ / mol)

Two identical antennas on identical towers are separated from each other by a distance of 45 km. What should be the minimum height of receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km)

A charge Q is moving dl distance in the magnetic field B. Find the value of work done by B