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:

Which of the following pairs of statements is correct?
1. (d) and (a)
2. (a) and (b)
3. (b) and (c)                                       
4. (c) and (d)

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 

1. $6000 \stackrel{\circ }{\mathrm{A}}$                                   
2. $4000 \mathrm{nm}$
3. $6000 \mathrm{nm}$                                 
4. $4000 \stackrel{\circ }{\mathrm{A}}$

The circuit is equivalent to

1. AND gate                              2. NAND gate

3. NOR gate                              4. OR gate 

In the forward bias arrangement of a PN-junction diode

(1) The N-end is connected to the positive terminal of the battery

(2) The P-end is connected to the positive terminal of the battery

(3) The direction of current is from N-end to P-end in the diode

(4) The P-end is connected to the negative terminal of battery

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