A cathode is an electrode where electric current exits a device. In energy-supplying devices, it is positively charged, while in energy-consuming devices, it is negatively charged. In electrochemical cells, the cathode is where reduction or gain of electrons occurs. In physics and electronics, the cathode emits electrons into the device. Cold cathodes are not directly heated, while hot cathodes are. Different types of metal have electrodes suitable for different methods of supplying electricity.
A cathode is an electrode through which electric current exits a polarized electrical device. Its opposite is the anode, through which electric current enters the electrical device. Positively charged ions, called cations, move towards the cathode, while negatively charged ions, called anions, move towards the anode. In devices that supply energy, such as discharging batteries, the cathode is positively charged, but in devices that consume energy, including recharging batteries, it is negatively charged.
In chemistry, a cathode is the electrode of an electrochemical cell where the reduction or gain of electrons occurs. If the electrochemical cell is electrolytic, i.e. supplied with electricity to break down chemical compounds, its cathode is negative. In the opposite type of electrochemical cell, the galvanic cell, chemical reactions cause the release of electrical energy, which becomes positive.
Negative polarity must be applied to the cathode of an electrolytic cell to drive the desired chemical reactions. In a galvanic cell, on the other hand, a positive pole must be connected to complete the circuit. The electrons emitted from the anode return to the cell through the cathode when the circuit is complete.
In physics and electronics, a cathode is the electrode responsible for emitting electrons into the device, making it work. The freely emitted electrons can be derived in various ways, either through heat or light energy, or through a strong external electromagnetic field. The latter method of driving electron emission is known as field electron emission and the cathodes involved are called cold cathodes.
While they can operate at high temperatures, cold cathodes are distinct from the “hot” variety because they are not directly heated to drive the emission of electrons. Hot cathodes, also known as filaments, are much more common in modern electronics. Cathodes that derive their energy from light are powered by photoelectric emissions and are used in photovoltaic or solar applications. Different types of metal have electrodes that are suitable for different methods of supplying electricity.
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