The conduction band in a solid is partially filled at 0 k. The solid sample is

In a p-type semiconductor, the acceptor level is situated 60m eV above the valence band. The maximum wavelength of light required to produce a hole will be [use hc = 12400eV ]

A semiconductor is cooled from \(T_{ 1 }K\ to\ T_{ 2 }k\) Its resistance will

In the middle of the depletion layer of a review biased p-n junction, the 

Choose the correct relation between the transistor parameters \(\alpha \ and\ \beta \)

Where does the fermi-level of intrinsic semiconductor lie?

Write the full form of the terms (i) SSI and
(ii) VLSI used for different types of integrated circuits.

Can we measure the potential difference of a \(p-n\) junction by putting a sensitive voltmeter across its terminals?

How is transistor biased to be in active state?

A digital circuit which either allows a signal to pass through or stops it, is called a.............

Define a hole. State its characteristics.

In a transistor connected in a common emitter mode it has, \(R_{ c }=4k\Omega \ ; \ R_{ i }=1k\Omega \ ; \ I_{ c }=1mA\) and \(I_{ b }=20\mu A\). Find the voltage gain.

What do you understand by the cut off, active and saturation states of the transistor? In which of these states does the transistor not remain when being used as a switch?

Identify the logic gates marked P and Q in the given circuit. Write the truth table for the combination.

Two car generates have a common gate which needs to open automatically when a car enters either of the garages or cars enter both. A circuit, that resembles this situation using diodes for this situation.

Give two advantages of LED's over the conventional incandescent lamps.

Carbon and silicon both have four valence electrons each, then how are they distinguished?

Two amplifiers are connected one after the other in series (cascaded). The first amplifier has a voltage gain of 10 and the second has a voltage gain 20. If the input signal is 0.01 volt, Calculate the output ac signal.

In the depletion region of a diode
(a) there are no mobile charges
(b) equal number of holes and electrons exist, making the region neutral.
(c) recombination of holes and electrons has taken place.
(d) immobile charged ions exist.

Suppose a pure Si crystal has \(5\times 10^{ 28 }\) atmos \(m^{ -3 }\). It is doped by ppm concentration of pentavalent As. Calculate the number of electrons and holes. Given that \({ n }_{ i }=1.5\times { 10 }^{ 16 }m^{ 3 }\)

Find the number density of impurity atoms that must be added to a pure silicon crystal inorder to convert it to have resistivity
(i) \(10^{ -1 }\Omega m\ n\)-type silicon
(ii) \(10^{ -1 }\Omega m\ p\)-type silicon. Given for silicon:\(\mu _{ e }=0.135{ m }^{ 2 }V^{ -1 }\ s^{ -1 }\) and \(\mu _{ h }=0.048{ m }^{ 2 }V^{ -1 }\ s^{ -1 }\) .

The resistivity of pure silicon is \(2500 \ \Omega m\), and the electron and hole mobilities are \(0.12 \ m^{ 2 } \ V^{ -1 } \ s^{ -1 }\) and \(0.045\ m^{ 2 }\ V^{ -1 }\ s^{ -1 }\) respectively. Determine
(i) the resistivity of a specimen of the material when \(10^{ 20 }\) atms of phosphorous are added per \(m^{ 3 }\).
(ii) The resistivity of a specimen if further \(=2\times 10^{ 20 }\) born atoms per \(m^{ 3 }\) are also added?

The current gain for common emitter amplifier is 69. If the emitter current is 7.0 mA, find
(i) base current and
(ii) collector current.

A half wave rectifier is used to supply 50 V d.c. to a resistance load of \(800\Omega \) . Diode has a resistance of \(200\Omega \) . Calculate maximum a.c. voltage required.

The resistivity of a pure germanium at a particular temperature is 0.54 \(\Omega \)m. If the material is doped with \(10^{ 20 }\) atoms per cubic metre of a trivalent impurity material, determine the new resistivity. The electron and hole mobilities are 0.24 \(m^{ 2 }\) \(V^{ -1 }s^{ -1 }\) and 0.18 \(m^{ 2 }V^{ -1 }s^{ -1 }\) respectively.

A pure semiconductor germanium or silicon,free of every impurity is called intrinsic semiconductor, At room temperature, a pure semiconductor has a very small number of current carriers (electrons and holes).Hence,its conductivity is low.
When the impurity atoms of valence five or three are doped in a pure semiconductor,we get respectively \(n-\) type or \(p-\) type extrinsic semiconductor.In case of a doped semiconductor.\({ n }_{ e }n_{ h }={ n }_{ i }^{ 2 };\)when \({ n }_{ e }\) and \(n_{ h }\) are the number density of electrons and holes respectively and \({ n }_{ i }\) is the number density of intrinsic charge carriers in a pure semiconductor. The conductivity of extrinsic semiconductor is much higher than that that of intrinsic semiconductor.
Read the above passage and answer the following question:
(i) Name two materials to be doped in pure semiconductor of silicon to get (a) \(p-\)type semiconductor (b) \(n-\)type semiconductor
(ii) What do you learn from the above study?

Prakash finds his friend Rakesh connecting his new television set directly to a awitch board. Prakash advises Rakesh not to do so and to connect the television through a voltage stabilizer.
(a) Identify the diode used in voltage regulator and give its symbol.
(b) What values dis, Prakash exhibit in the siuation described ?