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Materials and Components problems

1. An electron in a homogeneous magnetic field and having velocity perpendicular to the direction of field moves
Options
A. perpendicular to the field
B. along the field
C. along a straight line inclined at 45� to field
D. in a circular path

2. An homogeneous dielectric material is subjected to an electric field E. If a small cavity is made inside the material, the electric field intensity inside and outside the cavity are different.
Options
A. True
B. False

4. In an hydrogen atom, an electron moves in the field of a proton. The stability of orbit requires equilibrium between coulomb's force and centrifugal force.
Options
A. True
B. False

5. An electron shell corresponding to principal quantum number n can contain a maximum of
Options
A. n² electrons
B. 2n² electrons
C. 2n electron
D. n³ electron

6. Assertion (A): Dielectric losses are proportional to tan ?.
Reason (R): tan ? = where ?_r^' and ?_r^" denote the real and imaginary parts of ?_r.
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

8. For a core having a relative permeability ?_r, magnetic dipole moment per unit volume M and field strength H, the flux density B is
Options
A. B = ?_r (H + M)
B. B = ?₀ (H + M)
C. B = ?₀?_r (H + M)
D. B = ?₀?_r (H - M)

9. Figure shows a composite capacitor. If C_A, C_B, C_C are the capacitances of capacitors A, B, C, the overall capacitance C is
Options
A. C = C_A + C_B + C_C
B. C = (C_A + C_B) C_C
C. C =
D. C =

10. Assertion (A): In some materials, ?_r is independent of temperature while in others, ?_r depends on temperature.
Reason (R): If permanent dipoles are absent, ?_r varies with temperature.
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

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