Hydrogen is used in large size transformers MCB large size generators circuit br

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Correct Answer

large size generators

Explanation

Modem large size generators have hydrogen cooling.

Materials and Components problems

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1. A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must be
Options
A. halved
B. kept the same
C. doubled
D. made 4 times

2. For a permanent magnetic material
Options
A. the residual induction and coercive field should be large
B. the residual induction and coercive field should be small
C. area of hysteresis loop should be small
D. initial relative permeability should be high

3. If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1).
Options
A. True
B. False

4. Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger.
Options
A. True
B. False

5. If e is the charge of an electron, R is the radius of its orbit and ? is the angular velocity of electron, the magnetic dipole moment ?_m of the orbit is |?_m| = e?R².
Options
A. True
B. False

7. Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm² of surface.
Reason (R): Thermionic emission current is given by I_th = SA₀ T² e^-Ew/kT.
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): From the slope of the line in Figure, we can find permanent dipole moment of the molecules.
Reason (R): Total polarization of a polyatomic gas is given by P = N(a_e + a_i + ?²_p / 3kT)E.
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. Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature.
Reason (R): The orientation polarization is 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

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