In a metal, the drift velocity of electrons in the presence of a electric field

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Question
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

Correct Answer

proportional to E

Explanation

Drift velocity is proportional to field strength.

Materials and Components problems

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2. 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

3. 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

4. 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

5. In a piezoelectric crystal, the application of mechanical force will cause
Options
A. plastic deformation of crystal
B. magnetic dipoles in the crystal
C. electrical polarization in the crystal
D. shift in Fermi level

6. Inductors used at V.H.F. are made using
Options
A. air core
B. cast iron cored
C. sheet steel cored
D. thin film technique

7. 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

8. 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

10. 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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