Q221
Open questionAt what temperatures domains lose their ferromagnetic properties?
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ECE · all questionsMaterials And Components
Materials And Components
practice.
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248
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Q222
Open questionResistivity of Ge is
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Q223
Open questionSuperconductivity is destroyed
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Q224
Open questionWhich one of the following is the best definition of a superconductor?
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Q225
Open questionMatch List-I with List-II and select the correct answer:
| List-I | List-II |
| a. Ferro-magnetism | 1. d.c. electrical resistivity vanishes at the critical temperature TC |
| b. Semiconductor | 2. Doping with impurity increases the electrical conductivity |
| c. Optical property of solid | 3. An internal molecular field BM which is proportional to magnetization M exists at each dipole and aligns it parallel to other dipoles |
| d. Superconductivity | 4. Above the Neel temperature the dipoles become randomly oriented |
| 5. The conductivity of crystalline semiconductors and dielectrics increases by radiation incident |
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Q226
Open questionWhich of the following statements in NOT true?
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Q227
Open questionWhich one of the following materials is a ceramic material?
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Q228
Open questionConsider the following statements:
The conductivity of a metal has negative temperature coefficient since:
1. The electron concentration increase with temperature.
2. The electron mobility decreases with temperature.
3. The electron-lattice scattering rate increases with temperature.
Which of the above statements is/are correct?
The conductivity of a metal has negative temperature coefficient since:
1. The electron concentration increase with temperature.
2. The electron mobility decreases with temperature.
3. The electron-lattice scattering rate increases with temperature.
Which of the above statements is/are correct?
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Q229
Open questionPiezoelectricity is the reverse effect of
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Q230
Open questionConsider the following statements:
He-Ne laser
1. gives continuous output
2. emits red light
3. requires a DC magnet
4. can be voice modulated by using a Kerr cell
Which of these statements are correct?
He-Ne laser
1. gives continuous output
2. emits red light
3. requires a DC magnet
4. can be voice modulated by using a Kerr cell
Which of these statements are correct?
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Q231
Open questionThe piezoelectric effect is the polarization of a dielectric under the influence of
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Q232
Open questionThe superconductivity is due to
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Q233
Open questionThe dielectric strength of gaseous dielectric depends on which of the following factors?
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Q234
Open questionMatch List-I with List-II and select the correct answer using the options given below:
| List-I (Optical devices) | List-II (Electrical/optical characteristics) |
| a. GaAs | 1. Emits monochromatic light of low intensity |
| b. Solar cell | 2. Consumers electrical power due to the incident light |
| c. Photo Diode | 3. Deliver power to a load |
| d. LED | 4. Emits monochromatic light of light intensity |
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Q235
Open questionA large value of the exchange interaction energy in a ferromagnetic material implies.
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Q236
Open questionThe resistance of a metallic wire would
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Q237
Open questionWhich of the following represent the properties of carbon nanotubes?
1. High electrical conductivity
2. Very high tensile strength
3. High thermal conductivity
4. Low thermal expansion coefficient
Select the correct answer using the options given below:
1. High electrical conductivity
2. Very high tensile strength
3. High thermal conductivity
4. Low thermal expansion coefficient
Select the correct answer using the options given below:
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Q238
Open questionMaterials which lack permanent magnetic dipoles are known as
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Q239
Open questionA 'hole' in a semiconductor has
1. Positive charge equal to the electron charge
2. Positive mass equal to the mass of the electron
3. An 'effective mass' greater than the effective mass of electron
4. Negative mass and positive charge equal to the charge in nucleus
1. Positive charge equal to the electron charge
2. Positive mass equal to the mass of the electron
3. An 'effective mass' greater than the effective mass of electron
4. Negative mass and positive charge equal to the charge in nucleus
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Q240
Open questionThe magnetic field at which a superconductor remains in its superconducting state at a temperature less than the transition temperature is
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