One description would be forward biased.
due to high voltage across the diode ie more than piv of the diode or current flows more than maximum allowed range of diode.
A diode is made up of a P-Type and an N-Type semiconductor. P-Type has "missing" electrons (in a sense); N-Type has extra electrons (in a sense). This means that if you have current going through the two semiconductors from N-type into P-type, it should be easier than normal to apply the current because there is a potential difference between the N-type and P-type because of their relative "positivity" and "negativity". ...but if you reverse the voltage, then you are going against this potential difference and hence the voltage is impeded, resulting in a 0 current (in theory). This will only happen until the reverse voltage exceeds a threshold ampage, at which point the current will shoot up (in reverse).
A diode connected in this way is a flyback diode or kickback diode. There are some other names that may be applied. The diode is a protection device. When power to the coil is discontinued, the electromagnetic field around the coil will collapse. The collapse of that field will induce a voltage, and this could expose circuit elements to "kickback" from the field collapse. The polarity of the induced voltage will, however, forward bias the diode, and it will conduct current for an instant. The inductive kickback of the coil will thus be damped by that diode.
A rectifier diode normally allows current to pass in one direction (the forward direction), and almost no current in the opposite direction (the "reverse" direction). The diode is designed to work up to a certain voltage; if more than a certain voltage is applied in the reverse direction, it will "break down", and suddenly a large current will flow. This can irreparably damage the rectifier diode, unless it is of a type specifically designed to operate in the breakdown region - i.e., a Zener diode.
Any diode is less than 100% efficient because there is a forward voltage drop across the diode. This translates to power loss, because power is voltage times current.
ratio of ac voltage applied across the diode to the ac current flowing through it
if the voltage across the diode is less than the cut-in voltage of that particular diode .
An LED is a diode that emits light; diodes allow current to flow only one direction. The voltage applied to the diode attempts to force current to flow in a specific direction. If the voltage polarity is reversed, and current was flowing before (so there was a small voltage drop across the diode), current will cease to flow (assuming the voltage is not too high for the diode to handle), and (almost) all the voltage will be dropped across the diode (a small leakage current may flow, which means some of the voltage will not be dropped across the diode, but this is in the milli or micro range). I would never define a diode as a "voltage controller" or "current controller". It could be either or both, from the above description.
If the applied voltage is greater than maximum forward voltage, the diode will get damaged..
increases
The barrier potential of the silicon diode is 0.7v if the applied voltage across it is more than this voltage then PN-junction of the diode breaks, once pn-junction breaks the voltage across the diode is constant, since it breaks at 0.7 this voltage will be constant and not exceed for any further increase in applied voltage -inform.mayaprasad@gmail.com The voltage across junction will only exceed from 0.7 volt (for silicon diode) in the case of reverse biasing the applied total voltage will appear across p-n junction. ANSWER: .7 VOLTS is an arbitrarily chosen number since a diode any diode have an exponential curve V vs I . This number is chosen when using a diodes but there are times when a greater or lesser voltage is chosen to reflect the application and the current trough the diode determine that. Example a diode gate diode will be chosen as .6 volts rather then .7v and a heavy conducting rectifier may have .8 volt to reflect closely the true value of the diode drop during real conditions
-- The definition of 'reverse bias' is anode negative with respect to the cathode, or negative voltage across the diode. That places the graph in negative-x territory. -- The diode simply acts as a resistor. Its unique 'diode' characteristics arise from the fact that its 'resistance' changes with different bias points, but the current through it always has the same polarity as the voltage across it. Therefor . . . -- When the voltage across it is negative, the current through it is also negative. Negative current appears on the graph in negative-y territory. -- Negative-x territory/negative-y territory is the third quadrant.
As close to virtually zero volts as is possible: the current will very small but there will be current. This depends on two things: the material that is used to make the diode, and whether the voltage is applied in a forward or reverse direction to the diode. A typical silicon diode will pass forward current above 0.6 V and pass no reverse current until a much higher voltage is applied (check the rated peak inverse voltage PIV)
A diode is a semiconductor material which has p region and n region. In order to "turn on" and conduct current in the forward direction, a diode requires a certain amount of positive voltage to be applied across it. An ideal diode conducts only when the diode is forward biased, and then the voltage drop across the diode (Vd) is zero. When the ideal diode is reverse biased, no current flows. The two conditions to operate a diode are: (a) Current flow is permitted; the diode is forward biased. (b) Current flow is prohibited; the diode is reversed biased. When the polarity of the battery is such that current is allowed to flow through the diode, the diode is said to be forward-biased.
a diode and it has a constant voltage across it ANSWER: acts as a voltage regulator if enough current flows to create a breakdown voltage.
The voltage across a semiconductor diode (and across the base/emitter junction of a transistor) decreases as temperature increases: the actual figure is -2mV/°C.
The amount of (forward biased) voltage across a diode is dependent on current and temperature. A typical silicon diode has a forward voltage of about 0.6V at low current and temperature. As current goes up, voltage goes up slightly, with a typical voltage being 1.4V at high current. As temperature goes up, voltage goes down slightly, but the maximum current rating also goes down.