Q. Photo electric emission can occur only if

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Q. The reverse saturation current of a diode does not depend on temperature.

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Q. In a piezoelectric crystal, application of a mechanical stress would produce

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Q. The value of α in a transistor

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Q. The amount of photoelectric emission current depends on the frequency of incident light.

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Q. When a p-n junction is forward biased

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Q. The carriers of n channel JFET are

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Q. The depletion layer around p-n junction in JFET consists of

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Q. Junction temperature is always the same as room temperature.

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Q. Assertion (A): A p-n junction has high resistance in reverse direction.
Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases.

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Q. Assertion (A): When a high reverse voltage is applied to a p-n junction the diode breaks down.

Reason (R): High reverse voltage causes Avalanche effect.

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Q. If αac for transistor is 0.98 then βac is equal to

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Q. Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor.

Reason (R): The addition of donor impurity creates additional energy levels below conduction band.

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Q. A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10¯³⁴ J sec.

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Q. Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32 nA at 50°C.

Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature.

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Q. The value of a in a transistor

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Q. The intrinsic carrier concentration of silicon sample at 300 K is 1.5 x 1016/m³. If after doping, the number of majority carriers is 5 x 1020/m³. The minority carrier density is

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Q. Two identical silicon diodes D1 and D2 are connected back to back shown in figure. The reverse saturation current Is of each diode is 10-8 amps and the breakdown voltage VBr is 50 v. Evaluate the voltages VD1 and VD2 dropped across the diodes D1 and D2 assuming KT/q to be 25 m V.

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Q. An one sided abrupt junction has 10²¹/m³ of dopants on the lightly doped side, zero bias voltage and a built-in potential of 0.2 V. The depletion width of abrupt junction.(q = 1.6 x 10¯¹⁹ C, εr =16, ε₀ = 8.87 x 10¯¹² F/m) is

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Q. n-type semiconductors

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