# The output from a $$\mathrm{NAND}$$ gate is divided into two in parallel and fed to another $$\mathrm{NAND}$$ gate. The resulting gate is a:   1. $$\mathrm{AND}$$ gate 2. $$\mathrm{NOR}$$ gate 3. $$\mathrm{OR}$$ gate 4. $$\mathrm{NOT}$$ gate

Subtopic:  Logic gates |
78%
From NCERT
NEET - 2013
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In an unbiased $$\mathrm{p\text{-}n}$$ junction, holes diffuse from the $$\mathrm{p\text{-}}$$regions to $$\mathrm{n\text{-}}$$regions because of:
 1 the attraction of free electrons of the $$\mathrm{n\text{-}}$$region. 2 the higher hole concentration in the $$\mathrm{p\text{-}}$$region than that in the $$\mathrm{n\text{-}}$$region. 3 the higher concentration of electrons is in the $$\mathrm{p\text{-}}$$region than that in the $$\mathrm{n\text{-}}$$region. 4 the potential difference across the $$\mathrm{p\text{-}n}$$ junction.
Subtopic:  PN junction |
67%
From NCERT
NEET - 2013
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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. OR gate

2. AND gate

3. NAND gate

4. NOR gate

Subtopic:  Logic gates |
78%
From NCERT
AIPMT - 2010
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Pure Si at $$500~\text{K}$$ has an equal number of electron $$(n_e)$$ and hole$$(n_h)$$ concentrations of $$1.5\times10^{16}~\text{m}^{-3}$$. Doping by indium increases $$n_h$$ to $$4.5\times10^{22}~\text{m}^{-3}$$.  The doped semiconductor is of:

 1 $$p$$-type with electron concentration $$n_e=5\times10^9~\text{m}^{-3}$$ 2 $$n$$-type with electron concentration $$n_e=5\times10^{22}~\text{m}^{-3}$$ 3 $$p$$-type with electron concentration $$n_e=2.5\times10^{10}~\text{m}^{-3}$$ 4 $$n$$-type with electron concentration $$n_e=2.5\times10^{23}~\text{m}^{-3}$$
Subtopic:  Types of Semiconductors |
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From NCERT
AIPMT - 2011
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In the following figure, the diodes which are forward biased are:

 (a) (b) (c) (d)

1. (a), (b) and (d)
2. (c) only
3. (a) and (c)
4. (b) and (d)

Subtopic:  PN junction |
83%
From NCERT
AIPMT - 2011
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A Zener diode, having a breakdown voltage equal to 15 V, is used in a voltage regulator circuit as shown in the figure. The current through the diode is:

1. 5 mA
2. 10 mA
3. 15 mA
4. 20 mA

Subtopic:  Applications of PN junction |
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From NCERT
AIPMT - 2011
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To get output $$Y = 1$$ in the given circuit which of the following input will be correct?

 $$A$$ $$B$$ $$C$$ 1. 1 0 1 2. 1 1 0 3. 0 1 0 4. 1 0 0

Subtopic:  Logic gates |
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From NCERT
AIPMT - 2012
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The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B, and C are as shown below:

The logic circuit gate is:

1. AND gate

2. NAND gate

3. NOR gate

4. OR gate

Subtopic:  Logic gates |
75%
From NCERT
AIPMT - 2006
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Which of the following is an example of forward biasing?

 1 2 3 4
Subtopic:  PN junction |
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From NCERT
AIPMT - 2006
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In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is a/an:

1. p-type semiconductor

2. insulator

3. metal

4. n-type semiconductor

Subtopic:  Energy Band theory |
72%
From NCERT
AIPMT - 2007
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