Materials and Components problems
- 1. The direction of force an a conductor carrying current and lying in a magnetic field can be found by using
Options- A. Fleming's left hand rule
- B. Fleming's right hand rule
- C. Cork screw rule
- D. Any of the above Discuss
Correct Answer: Fleming's left hand rule
- 2. The real part of complex dielectric constant and tan? for a dielectric are 2.1 and 5 x 10-4 at 100 Hz respectively. The imaginary part of dielectric constant at 100 Hz is
Options- A. 1.05 x 10-3
- B. 2.1 x 10-3
- C. 5 x 10-3
- D. 1.05 x 10-2 Discuss
Correct Answer: 1.05 x 10-3
Explanation:
- 3. A single layer air cored coil has n turns and inductance L. If a new coil is formed by having 2n turns while keeping the coil length and diameter the same, the new inductance is
Options- A. 0.5 L
- B. L
- C. 2 L
- D. 4 L Discuss
Correct Answer: 4 L
Explanation:
Inductance is proportional to square of number of turns.
- 4. 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
Correct Answer: Neel temperature
- 5. 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
Correct Answer: x << R
- 6. The units for electric dipole moment are
Options- A. coulombs
- B. colomb-metre
- C. coulomb/metre
- D. coulomb/m2 Discuss
Correct Answer: colomb-metre
Explanation:
It is product of charge and distance.
- 7. For a superconductor, the relative permeability is
Options- A. zero
- B. high
- C. low
- D. either low or high Discuss
Correct Answer: zero
- 8. 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
Correct Answer: Both A and R are true but R is not correct explanation of A
Explanation:
Conductivity does not depend on lattice structure.
- 9. 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 Discuss
Correct Answer: 1.43 eV
- 10. 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
Correct Answer: A is true but R is false
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