Electronic Science

Electronic Science

Electronic Science
| Electronic Devices | | Magnetism and Matter | | Moving Charges and Magnetism | | Current Electricity | | Electrostatic Potential and Capacitance | | Digital Logic | | Digital Circuits | | Analog Circuits | | Electronic Devices | | Power Electronics | | Electrical and Electronic Measurements | | Electric Circuits |
Q.1
Basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc are
A. Semiconductors
B. metals
C. insulators
D. conductors
Answer : Option A
Explaination / Solution:

Semiconductors are materials that have electrical conductivity between conductors such as most metals and nonconductors or insulators like ceramics. Semiconductor material is used in the manufacturing of electrical components and used in electronic devices such as transistors and diodes. Semiconductors are the basic materials used in the present solid state electronic devices like diode, transistor, ICs etc

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Q.2
in n-type semiconductor majority carriers and minority carriers are respectively
A. germanium and silicon
B. electrons and holes
C. aluminum and boron
D. holes and electrons
Answer : Option B
Explaination / Solution:

N-type semiconductors have a larger electron concentration than hole concentration. The term n-type comes from the negative charge of the electron. In n-type semiconductors, electrons are the majority carriers and holes are the minority carriers. N-type semiconductors are created by doping an intrinsic semiconductor with donor impurities (or doping a p-type semiconductor as done in the making of CMOS chips). A common dopant for n-type silicon is phosphorus.

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Q.3
In an insulator, the forbidden energy gap between the valance band and conduction band is of the order of
A. 1 eV
B. > 5 eV
C. 2 MeV
D. eV
Answer : Option B
Explaination / Solution:

In an insulator, the forbidden energy gap is very large.In general, the forbidden energy gap is more than 5eV and almost no electrons are available for conduction. Therefore, a very large amount of energy must be supplied to a valence electron to enable it to move to the conduction band. In the case of materials like glass, the valence band is completely filled at 0 K. The energy gap between valence band and conduction band is of the order of 10 eV. Even in the presence of high electric field, the electrons cannot move from valence band to conduction band.

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Q.4
The conductivity of P – type semiconductor is due to
A. holes
B. electrons
C. none of the above.
D. both electrons and holes
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.5
For forward biasing a P-N junction the positive terminal of the battery is connected to
A. N – type crystal
B. Neither P – type nor N – type crystal
C. P – type crystal
D. Either P –type or N – type crystal
Answer : Option C
Explaination / Solution:

Biasing is the application of a voltage across a p–n junction.

When we connect p-type region of a junction with the positive terminal of a voltage source and n-type region with the negative terminal of the voltage source, then the junction is said to be forward biased.

At this condition, due to the attraction of positive terminal of source, electrons which participated in covalent bond creations in p-type material, will be attracted towards the terminal.


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Q.6
which of the following statements about earth's magnetism is correct
A. The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to the north.
B. The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-west to the north-east.
C. The earth behaves as a magnet with the magnetic field pointing approximately from the geographic east to the west.
D. The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south-east to the north-west.
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.7
considering the magnetic field of the earth,the correct relation of the geographic pole and the magnetic poles is
A. north magnetic pole is located near the south geographic pole and south magnetic pole is located near the north geographic pole
B. north magnetic pole is located near the south geographic pole but south magnetic pole is not located near the north geographic pole
C. north magnetic pole is not located near the south geographic pole but south magnetic pole is located near the north geographic pole
D. north magnetic pole is located near the north geographic pole
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.8
permanent magnets should have
A. low retentivity and high coercivity
B. high retentivity and high coercivity
C. high retentivity and low coercivity
D. low retentivity and low coercivity
Answer : Option B
Explaination / Solution:
No Explaination.


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Q.9
Nitric oxide is a paramagnetic compound. The magnetic moment of each NO molecule has a maximum component in any direction of about one Bohr magneton.Interaction energy of such magnetic moments in a 1.5-T magnetic field is
A. 8.7×105eV
B. 9.0×105eV
C. 8.9×105eV
D. 8.4×105eV
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.10
A short bar magnet placed with its axis at  with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to J. What is the magnitude of magnetic moment of the magnet?
A. 0.30 J/T
B. 0.36 J/T
C. 0.33 J/T
D. 0.26 J/T
Answer : Option B
Explaination / Solution:
No Explaination.


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