The energy band gap is maximum in

metals
superconductors
insulators
semiconductors.

Solution

Maximum in in sulators and overlaping in metals

By increasing the temperature, the specific resistance of a conductor and a semiconductor

increases for both
decreases for both
increases, decreases
decreases, increases

Solution

The resistivity of conductor increases with increase in temperature. The resistivity of semiconductor decreases as the temperature increases

A semi-conducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The devicemay be

ap-n junction
an intrinsic semi-conductor
ap-type semi-conductor
an n-type semi-conductor

Solution

In reverse bias the current through the p-n junction is almost zero.

Application of a forward bias to a p–n junction

widens the depletion zone
increases the potential difference across the depletion zone
increases the number of donors on then side
increases the electric field in the depletion zone.

Solution

Number of donors is more because electrons from –ve terminal of the cell pushes (enters) the n side and decreases the number of uncompensated pentavalent ion due to which potential barrier is reduced. The neutralised pentavalent atom are again in position to donate electrons.

Carbon, Silicon and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (E_g)_C,(E_g)_Si and(E_g)_Ge respectively. Which one of the following relationship is true in their case?

(E_g)_C > (E_g)_Si
(E_g)_C < (E_g)_Si
(E_g)_C = (E_g)_Si
(E_g)_C < (E_g)_Ge

Solution

Due to strong electronegativity of carbon.

Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54 Å. The value of lattice constant for this lattice is

2.54 Å
3.59 Å
1.27 Å
5.08 Å

Solution

A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20Ω across source. If 0.1 A current passes through resistance then what is the voltage of the source?

1.5 V
2.0 V
2.5 V
5 V

Solution

The frequency response curve of RC coupled amplifier is shown in figure. The band with of the amplifier will be

f₃ – f₂
f₄ – f₁
\(\frac{f_{4}-f_{2}}{2}\)
f₃ – f₁

The ratio of work function and temperature of two emitters are 1 :2, then the ratio of current densities obtained by them will be

4 : 1
2 : 1
1 : 2
1 : 4

Solution

The grid voltage of any triode valve is changed from –1 volt to –3 volt and the mutual conductance is 3× 10^-4mho.The change in plate circuit current will be

0.8 mA
0.6 mA
0.4 mA
1 mA

Solution

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