Electronics Engineering

when rectifier is on, the capacitor is almost transparent (it charges to the voltage provided from the rectifier)

when rectifier is off, capacitor holds the peak voltage since it stored a charge during rectifier on time.

maximum forward current in diode IN4007 is 30 amp

That'd be a relay.

frequency drops

İf hunger was a positive feedback, no one would ever eat, so the entire human race would bee wiped out.

Hunger is a very wide term. Extreme from starvation all the way to over eating.... different levels of hunger give positive and negative feedback. One can learn to read these signal through mindfulness, gratitudeand eating in moderation.

series resonant circuit

A diode may be built for high levels of current and voltage. There are diodes for low current and voltages too. They allow the ac current to flow one way and block its return. The first diode that was built a long time ago by Sylvania Co. USA, was named IN34, and could stand only very low current.

Other name for that device is a rectifier. Ancient valve tubes for radios contained a diode inside which main function was to provide cc to feed the filament of a valve. This filament had the function of emitting electrons towards the plate of the valve.

JW70

This may vary by make and model of toaster and the intended operating voltage.

For a North American toaster designed to operate on a 15 ampere outlet at 120 volts RMS, the hot resistance cannot be any less than 8 ohms. By their nature, heating elements have a lower resistance when cold, so an 8 ohm element needs to be used on a circuit that is protected by a thermal time-delay circuit breaker; an ordinary fuse is likely to burn out during the several seconds it takes for the element to heat up and the current to reach the steady-state "hot" current. Due to the uncertainty of the circuit protection scheme, manufacturers will limit the current, and thus the power level of appliances such as toasters to something less than the maximum theoretical capacity of the circuit. For example, a toaster with an 8 ohm steady state hot resistance will draw 1800 watts. More realistically, the device will be designed to draw 1200 watts, and thus its hot resistance will be 12 ohms.

there is no such thing

Because most of the heat buildup occurs in the reverse biased collector-base junction where Ic = Ie + Ib flows.

Transmission bandwidth depends on modulating signal frequency and carrier frequency

C is a conductor, so valence and conduction bands overlap.

if you mean SiC, silicon carbide, energy gap is ~2.86eV @ 300K (ambient temperature)

Approximately 70

If you mean the capacity of the capacitor then,

Factors are:-

Area of of overlap of the plates

Separation of the plates

How good is the insulating material between the plates (the dielectric)

If you mean how large a charge can be stored then,

Factors are:-

The capacitance of the capacitor (C).

The applied voltage (V).

Charge Q =CxV

V cannot exceed the dielectric's breakdown voltage.

In almost any modern electronic device.

chest compressions not effective

Selection and setting of a transistor's operating pointto meet circuit functional requirements.

binary coded decimal counter with carry propagated bit to bit by ripple method instead of carry lookahead combinatorial logic method. this is easy to build but has long settling time with invalid codes occurring before it settles. for example these counters will generate a 1010 code between 1001 and 0000.

9, 8 to shift the bits in & 1 to move the byte into another register.

power supplied=sum of powers delivered to individual elements

Fixed Bias,Self Bias,

Forward Bias, Reverse Bias

Yes, of course but you must first expand the devices to equivalent circuit models of the appropriate approximation level to get reasonable answers. Such equivalent circuit models will have anywhere from 3 or 4 components to dozens depending on approximation level.

The detailed answer would involve quantum physics, with terms such as the Fermi level, the Fermi statistics, and the band gap.

In short, a band gap forms in a pure semiconductor crystal lattice, such as that of silicon or gallium arsenide, in a wide temperature range (roughly above the absolute zero and below the melting point of the solid). The bandgap just means that carriers, electrons or holes, cannot occupy energy levels within the bandgap. The bandgap for pure silicon at room temperature is about 1.1eV. In perspective, a particle at room temperature has a thermal energy of 0.026eV, so 1.1 eV is a big chunk of energy that an electron has to acquire to jump the gap. Statistics describes how much of the electron population has the probability of acquiring such energy. Above the forbidden band is called the conduction bands for electrons to roam with or without the aid of an electric field. Below the gap is called the valence band, where holes travel like a vacancy (the lack of an electron). Under the influence of an electric field, holes will have a net drift toward the negative electrode and electrons toward the positive.

Introducing impurities into the pure solid will create trap levels within the band gap. That is, impurities always introduce imperfection. These trap levels act like a rest station, allowing electrons to be excited from the valence band to the conduction band (equivalent to holes being excited from the conduction band to the valence band) in two trips instead of one giant leap, from the top of the valence band to the trap, and then from the trap to the bottom of the conduction band. Introducing boron atoms to the silicon solid will create trap levels near the valence band; arsenic or phosphorus atoms will create traps near the conduction band. The introduction of impurities intentionally is called doping. Boron doping is called p-type (p stands for positive) and arsenic or phosphorus doping, n-type (n stands for negative).

At room temperature, trap levels at slightly different energy levels in the bangap exist, but p-type doping creates traps near the top of the valence band and n-doping creates traps near the bottom of the conduction band. The Fermi level is the 50% energy level where half of the electron population can ideally be above and half below. The Fermi level is normally located where the trap levels are. At the absolute zero temperature, all electrons will be below the Fermi level, i.e. the valence band; all holes will be in the conduction band. At room temperature, some electrons acquire enough energy to jump the gap to occupy the bottom of the conduction band. Because of the forbidden gap, the levels that an electron can occupy are not always present in the bandgap.

Technology has allowed p-doping and n-doping to happen consecutively and in adjacent regions in the silicon solid, to form a pn junction or diode junction. On the p-side, there is an excess of holes. Electrons are in abundancy on the n-side. By the theory of diffusion, excess holes like to diffuse to the n-side and excess electrons to the p-side.

Diffusion is evident in real life. For example, human beings treasure a personal space. If everyone stands near the punch bowl at the party, someone will feel uncomfortable and move away from the table. Viola, diffusion ensures. However, nature is such that when too many electrons move to the p-side, the next electrons will have need more and more energy to overcome the repulsion from the electrons that have already migrated. Holes do the same. Eventually (microseconds is a long time in electronics), things will settle down. The phenomenon is called the thermal equilibrium. Equal numbers of electrons are crossing from p to n as from n to p. This reluctance to have more electrons migrating from n to p than from p to n is described as that an energy barrier has formed. This energy barrier is approximately 0.7 eV, which is the origin of the 0.7 V in the question, when converting from energy in [eV] to a voltage in [V] for one electron. The Fermi level plays a role of 0.7 eV here -- the Fermi level on the n-side has to align to the Fermi level on the p-side. Lining up the Fermi level on both p- and n-sides creates the potential barrier. Applying a positive bias to the p-side relative to the n-side will lower the potential barrier, causing a positive current -- electrons flowing from the negative terminal to the positive, while holes do the opposite.

Mathematically, this phenomenon can be written as I = Io * [exp(qV/kT) - 1], the diode equation. In this equation, what is important for understanding is that I is the current the diode will conduct for a certain voltage applied, V. V assumes a positive value when the anode is biased more positive than the cathode or the pn junction is forward biased. Conversely, the diode is reverse biased. At room temperature, the term (kT/q) takes on a value of 0.026 V. The value for Io for silicon at room temperature is, let us say, 1E-12 A. Plugging the known values in the diode equation for an increasing V, we get the following pairs of (V,I) values:

V [volts] I [amperes]

0 1E-12

0.1 4.58E-11

0.2 2.19E-09

0.3 1.03E-07

0.4 4.80E-06

0.5 2.25E-04

0.6 1.05E-02

0.7 4.93E-01

At a forward bias of 0.7V, the diode is basically a short circuit, meaning the electric field intensity is so high that practically any electrons near the pn junction on the n-side are swept across to the p-side. Recall that holes do the opposite. The potential barrier has been practically overcome/breached.

In parallel circuit resistance goes with an inverse relation as:

1/Rn = 1/R1+1/R2+1/R3.....

so Power P = V2/R will follow the same proportionality only.