Materials and Components – Section 3
21. | The dielectric constant of ferroelectric materials can be expressed by the equation | |||||||
Answer: Option A |
23. | Assertion (A): Orbital magnetic moment of an electron in an atom is of the order of 1 Bohr magneton.
Reason (R): 1 Bohr magneton = 9.27 x 10-24 A/m2. |
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Answer: Option B |
24. | As per Bohr’s postulate, only those circular orbits are stable for which the angular momentum is equal to an integer times ![]() ![]() ![]() ![]() |
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Answer: Option A Explanation: It is a quantum condition postulated by Bohr. |
25. | Inductors used at V.H.F. are made using | |||||||
Answer: Option D Explanation: Thin film technique ensure low hysteresis and eddy current losses. |
26. | If a capacitor C having selectivity factor Q is scaled down in all its dimensions by a factor K without any altering the dielectric material, the new capacitor will have capacitance and selectivity as | |||||||
Answer: Option B Explanation: Since the dimension of plates is scaled down by K, the area decreases by a factor of K2, the distance between plates decreases by a factor of K. Therefore, capacitance changes to The selectivity will not be affected. |
27. | The hysteresis loss is | |||||||
Answer: Option A |
28. | If m, v, r are the mass, velocity and radius of orbit of electron and h is Planck’s constant, quantum condition for electron’s orbit is | |||||||
Answer: Option B Explanation: For stable circular orbit angular momentum is equal to integer times |
29. | Assertion (A): For a magnetic material M = (μr – 1) H, where M is magnetic dipole moment/m3, H is field intensity A/m and μr is relative permeability.
Reason (R): μr can have any value from 0 to hundreds of thousands. |
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Answer: Option C Explanation: μr is always more than 1. It cannot be 0 or less than 1. |
30. | As regards ∈0 and ∈r (absolute and relative permittivity) | |||||||
Answer: Option B |