12th Class Physics MCQS
Those materials whose resistivity becomes zero at certain temperature is called:
Conductor
Insulator
Semiconductor
Super conductor
The temperature at which, semiconductor behaves as insulators:
None of above
10k
0k
237k
Which of the modulus of elasticity is involved in compressing a rod to decrease its length ?
Modulus of elasticity
Bulk modulus
None of these
Young’s modulus
Semiconductors have conductivity of order:
10-6 to 10-4 (?m)-1
102 to 105 (?m)-1
10-8 to 10-6 (?m)-1
10-5 to 10-7 (?m)-1
Yield stress is another name of
Plasticity
Both (b) and (c)
Proportional limit
Elastic limit
Recentaly a complex crystalline structure known as yttrium barium copper oxide (Yba2 Cu3 O3) have reported to become super conductor at
100 K
200 K
163 K
169 K
The domain theory of magnet is important to explain the behaviour of
Ferromagnets
Diamagnets
All of these
Paramagnets
Insulators have:
Al full valence band
An empty conduction band
A large energy gap
All of above
A pentaralent impurity in Si
a free hole
a free electron
a free electron and a free hole
No free particle
The curie temp for iron is about
800oC
650oC
740oC
750oC
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