Help is available everywhere. This is the unit of electrical current flow. The rate at which current flows past a given point. A passive network comprising usually, but not always, resistors that reduces the power or voltage level of a signal without introducing significant distortion. This is a relative power unit.
Direct current is where at all times the voltage polarity remains constant.
D.C. may however, particularly where it is rectified from mains a.c., contain residual a.c. superimposed or part of the voltage. This is often referred to as mains hum. A dipole is an antenna. It is a fundamental form of antenna consisting of a single wire whose length is approximately equal to half the transmitting wavelength. The actual physical length in practice is slightly different from this owing to other factors.