Inductors used at V.H.F. are made using air core cast iron cored sheet steel cor

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Correct Answer

thin film technique

Explanation

Thin film technique ensure low hysteresis and eddy current losses.

Materials and Components problems

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1. In a metal, the drift velocity of electrons in the presence of a electric field E is
Options
A. proportional to E
B. proportional to E
C. inversely proportional to E
D. proportional to E²

3. Assertion (A): In Figure, the intercept of the line on y-axis is equal to N (a_e + a_i), where N is number of atoms/m³, a_e is electronic polarizability and a_i is ionic polarizability.
Reason (R): a_e and a_i are independent of 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

4. Assertion (A): If difference between static and optical dielectric constant is high, the mechanical compressiblity of that material is also high.
Reason (R): For soft ions, ionic polarization per unit field is higher than that of hard ions.
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

5. A piece of iron is placed in a magnetic field
Options
A. the magnetic field will not be affected
B. the magnetic lines of force will bend to pass through the piece
C. the magnetic lines of force will bend away from the piece
D. any of the above depending on type of iron

6. Assertion (A): The resistance of a copper specimen changes by about 22% when temperature is increased from room temperature to 700�C.
Reason (R): The physical properties of a material are determined mostly by the extent of impurities.
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

7. Assertion (A): For elemental dielectrics, P = Na_eE_i where N is number of atoms/m³, P is polarization, a_e is electronic polarization and E_i is internal electric field.
Reason (R): In elemental dielectrics there are no permanent dipoles or ions.
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

9. 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
Options
A. C,
B. , Q
C. ,
D. C, K

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