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- Question
The wavelength of light emitted by GaAs laser is 8670 x 10-10 m. If h = 6.626 x 10-34 Js, velocity of light = 3 x 108 m/s and eV = 1.602 x 10-19 J, the energy gap in GaAs is
Options- A. 0.18 eV
- B. 0.7 eV
- C. 1.43 eV
- D. 2.39 eV
- Correct Answer
- 1.43 eV
- 1. Assertion (A): Copper is a good conductor of electricity.
Reason (R): Copper has a face centred cubic lattice.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
- 2. For a superconductor, the relative permeability is
Options- A. zero
- B. high
- C. low
- D. either low or high Discuss
- 3. The units for electric dipole moment are
Options- A. coulombs
- B. colomb-metre
- C. coulomb/metre
- D. coulomb/m2 Discuss
- 4. When the atom of rare gas is placed in an electric field the nucleus shifts from the centre of electron cloud by an amount x. If the radius of electron cloud is R, then
Options- A. x << R
- B. x ≂ 0.5 R
- C. x ? 0.75 R
- D. x ? R Discuss
- 5. In anti-ferromagnetic materials, the graph of susceptibility versus temperature shows a sharp maximum at a certain temperature. This temperature is known as
Options- A. Curie temperature
- B. Neel temperature
- C. Weiss temperature
- D. Bitter temperature Discuss
- 6. Assertion (A): Relative permittivity is determined by the atomic structure of the material.
Reason (R): Absolute permittivity is determined by the atomic structure of the material.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
- 7. The core of an atom consists of
Options- A. nucleus
- B. nucleus and all orbits
- C. nucleus and inner orbits
- D. none of the above Discuss
- 8. Diamagnetic materials do not have permanent magnetic dipoles.
Options- A. True
- B. False Discuss
- 9. Assertion (A): Rochelle salt and Barium titanate are both ferroelectric.
Reason (R): Ferroelectric materials exhibit hysteresis effect.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
- 10. If a metal specimen has n valence electrons per m3 each having charge e and mass m and t is the relaxations time, the conductivity is
Options- A.
- B.
- C.
- D.
Discuss
Materials and Components problems
Search Results
Correct Answer: Both A and R are true but R is not correct explanation of A
Explanation:
Conductivity does not depend on lattice structure.
Correct Answer: zero
Correct Answer: colomb-metre
Explanation:
It is product of charge and distance.
Correct Answer: x << R
Correct Answer: Neel temperature
Correct Answer: A is true but R is false
Correct Answer: nucleus and inner orbits
Correct Answer: True
Correct Answer: Both A and R are true but R is not correct explanation of A
Explanation:
Both the materials exhibit ferroelectric properties. Hysteresis effect is one of the features of ferroelectric materials.
Correct Answer:
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