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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 2
6.
When a material becomes a superconductor, its resistivity becomes
very small
zero
about 10% of normal value
about 20% of normal value
Answer: Option
Explanation:

A superconductor has zero resistance.

7.
In a piezoelectric crystal, the application of mechanical force will cause
plastic deformation of crystal
magnetic dipoles in the crystal
electrical polarization in the crystal
shift in Fermi level
Answer: Option
Explanation:

Piezoelectric materials permit conversion of mechanical force into electrical energy.

8.
Consider the following statement
If an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is
  1. both due to electrons and holes with electrons as majority carriers
  2. sum of hole and electron currents
  3. difference between electron and hole currents.
Which of above statements are correct?
1 only
1 and 2
2 only
3 only
Answer: Option
Explanation:

The net current is sum of currents due to holes and electrons.

In n type materials, electrons are majority carriers.

9.
As the temperature of a pure silicon specimen is increased
the number of free electrons increases
the number of holes decreases
the number of holes increases
the number of free electrons and holes increases
Answer: Option
Explanation:
No answer description is available. Let's discuss.
10.

Assertion (A): In many materials, dielectric polarization causes mechanical distortion.

Reason (R): If dielectric polarization causes mechanical distortion then mechanical distortion must cause dielectric polarization.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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