Engineering :: Engineering Materials
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| 391. |
Which type of electron pair exists in a semi-conductor? |
| A. |
Ionic |
B. |
Non-ionic |
| C. |
Homopolr |
D. |
Hetropolar |
Answer: Option C
Explanation:
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| 392. |
Selenium is an |
| A. |
intrinsic semi-conductor |
B. |
extrinsic semi-conductor |
| C. |
p-type semi-conductor |
D. |
n-type semi-conductor |
Answer: Option A
Explanation:
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| 393. |
Silicon doped with phosphorous is an |
| A. |
intrinsic semi-conductor |
B. |
extrinsic semi-conductor |
| C. |
p-type semi-conductor |
D. |
n-type semi-conductor |
Answer: Option D
Explanation:
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| 394. |
Silicon doped with gallium is |
| A. |
intrinsic semi-conductor |
B. |
extrinsic semi-conductor |
| C. |
p-type semi-conductor |
D. |
n-type semi-conductor |
Answer: Option C
Explanation:
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| 395. |
A material with unequal anti-parallel atomic magnetic moments is |
| A. |
an anti-ferromagnetic |
B. |
ferrimagnetic |
| C. |
ferrite |
D. |
non-magnetic |
Answer: Option A
Explanation:
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| 396. |
The permeability of soft iron can be increased by |
| A. |
purifying it |
B. |
reducing carbon percentage |
| C. |
alloying with cobalt |
D. |
increasing carbon percentage |
Answer: Option C
Explanation:
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| 397. |
When a ferromagnetic substance is magnetised, small changes in dimensions occur. Such a phenomenon is known as |
| A. |
magnetic hysteresis |
B. |
magnetic expansion |
| C. |
magneto striction |
D. |
magneto-calorisation |
Answer: Option C
Explanation:
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| 398. |
High purity copper is obtained by |
| A. |
casting |
B. |
rolling |
| C. |
induction heating |
D. |
electric refining |
Answer: Option D
Explanation:
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| 399. |
Which variety of copper has the best mechanical strength? |
| A. |
Annealed copper |
B. |
Hard drawn copper |
| C. |
Cast copper |
D. |
Soft copper |
Answer: Option B
Explanation:
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| 400. |
Nickel is used in |
| A. |
cutting tools |
B. |
automatic voltage regulators |
| C. |
electrodes of thermionic valves |
D. |
pressure sensitive elements |
Answer: Option C
Explanation:
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