Which one of the following statement is false?

(1) Pure Si doped with trivalent impurities gives a p-type semiconductor 

(2) Majority carries in a n-type semiconductor are holes

(3) Minority carries in a p-type semiconductor are electrons

(4) The resistance of intrinsic semiconductor decreases with increase of temperature 

To get an output Y =1 from the circuit shown below, the input must be

        A     B     C

(1)   0      1     0

(2)   0      0     1

(3)   1      0     1

(4)   1      0     0

The following figure shows a logic gate circuit with two inputs A and B and the output Y. The voltage waveforms of A, B and Y are as given

The logic gate is 

(1) $\mathrm{NOR}$ gate                                                 

(2) $\mathrm{OR}$ gate

(3) $\mathrm{AND}$ gate                                                 

(4) $\mathrm{NAND}$gate

For transistor action

(1) Base, emitter and collector regions should have similar size and doping concentrations.

(2) The base regions must be very thin and lightly doped.

(3) The emitter-base junction is forward biased and the base-collector junction is reverse biased.

(4) Both the emitter-base junction as well as the base-collector junction are forward biased.

Which of the following pairs of statements is correct?

(a)   (4) and (1)                                       (b)   (1) and (2)

(c)   (2) and (3)                                       (d)    (3) and (4)

A p-n photodiode is fabricated from a semiconductor with a band gap of $2.5 \mathrm{eV}.$ It can detect a signal of wavelength 

(a) $6000 \stackrel{\circ }{\mathrm{A}}$                                    (b) $4000 \mathrm{nm}$

(c) $6000 \mathrm{nm}$                                  (d) $4000 \stackrel{\circ }{\mathrm{A}}$

The circuit is equivalent to

1. AND gate                              2. NAND gate

3. NOR gate                              4. OR gate 

The electrical circuit used to get smooth output from a rectifier circuit is called 

(1) Oscillator                         

(2) Filter

(3) Amplifier                           

(4) Logic gates

PN-junction diode works as a insulator, if connected

(1) To A.C.                             

(2) In forward bias
(3) In reverse bias                   

(4) None of these

The PN junction diode is used as

(1) An amplifier                       

(2) A rectifier
(3) An oscillator                       

(4) A modulator

Two PN-junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be 

(a) In the circuit (1) and (2)                    (b) In the circuit (2) and (3)
(c) In the circuit (1) and (3)                    (d) Only in the circuit (1)