A Transformer is a device that transfers electrical energy from one circuit to another through inductively coupled electrical conductors. A changing current in the first circuit (the primary) creates a changing magnetic field; in turn, this magnetic field induces a changing voltage in the second circuit (the secondary). By adding a load to the secondary circuit, one can make current flow in the transformer, thus transferring energy from one circuit to the other. A key application of transformers is to reduce the current before transmitting electrical energy over long distances through wires. Most wires have resistance and so dissipate electrical energy at a rate proportional to the square of the current through the wire. By transforming electrical power to a high-voltage (and therefore low-current) form for transmission and back again afterwards, transformers enable economic transmission of power over long distances. Consequently, transformers have shaped the electricity supply industry, permitting generation to be located remotely from points of demand. Transformers are used extensively in consumer electronic products to step down the supply voltage to a level suitable for the low voltage circuits they contain. In these kind of applications the transformer may also act as a key safety component that electrically isolates the end user from direct contact with the potentially lethal supply voltage.

Electrical test equipment is essential for electrical systems.Practical electrical engineering and assembly requires the use of many different kinds of electrical test equipment ranging from test light consisting of just a light bulb and a test lead to extremely complex and sophisticated such as Automatic Test Equipment. Advanced test gear is necessary when developing circuits and systems that is needed when doing production testing or when troubleshooting existing production units in the field.The products used for basic measurement of voltages, currents and components in the circuit under test include voltmeter, ohmmeter, ammeter and multimeter.

Diathermy refers to the use of high-frequency electromagnetic waves (greater than 10 MHz) as therapeutic stimuli. Shortwave diathermy uses waves of 13, 27, or 45 MHz, while microthermy uses waves of up to 2450 MHz in frequency. Both forms of diathermy generate heat in deep muscle tissue, although microthermy is believed to be absorbed more by superficial fatty issue. The patient is placed between the electrodes, and the power level is adjusted until the patient reaches resonance (as determined by automated measurement systems) with a pre-established heating level. Each diathermy session lasts 10-30 minutes, depending on the size of the target area. The heat generated by diathermy improve blood circulation, relax muscular tension and promote drainage in the target areas.

Electrotherapy is the use of electrical energy in the treatment of impairments of health and a conditions of abnormal functioning. In medicine, the term electrotherapy can apply to a variety of treatments, including the use of direct current in cardioversion and the use of electrical devices such as deep brain stimulators for neurological disease. The term has also been applied specifically to the use of electrical current to speed wound healing. Electrotherapy is used for a variety of needs among which: relaxation of muscle spasms, prevention and retardation of disuse atrophy, increase of local blood circulation; muscle rehabilitation and reeducation; maintaining and increasing range of motion; management of chronic and intractable pain, post traumatic acute pain, post surgical acute pain, immediate post-surgical stimulation of muscles to prevent venous thrombosis, wound healing and drug delivery.

Electric Stimulator is an electronic device that produces electrical signals used to stimulate nerves through unbroken skin.The unit is usually connected to the skin using two or more electrodes. A typical battery-operated unit consists of a pulse generator, small transformer, frequency and intensity controls, and a number of electrodes.

Earphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a stereophonic, monophonic or binaural audio-frequency signal source such as an audio amplifier, radio or CD player. In the context of telecommunication, the term headset is used to describe a combination of headphone and microphone used for two-way communication, for example with a telephone.