A progressive wave is given by, $$\mathrm{Y}=12 \sin (5 \mathrm{t}-4 \mathrm{x})$$. On this wave, how far away are the two points having a phase difference of $$90^{\circ}$$ ?

The de-Broglie wavelength $$(\lambda)$$ of a particle is related to its kinetic energy (E) as

For a purely inductive or a purely capacitive circuit, the power factor is

The electric field intensity on the surface of a solid charged sphere of radius '$$r$$' and volume charge density '$$\rho$$' is ($$\varepsilon_0=$$ permittivity of free space)