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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 1
31.
For a paramagnetic material, susceptiblity increases with increasing temperature.
True
False
Answer: Option
Explanation:

Susceptibility ∝ .

32.
Hydrogen is used in
large size transformers
MCB
large size generators
circuit breakers
Answer: Option
Explanation:

Modem large size generators have hydrogen cooling.

33.

Assertion (A): Ferroelectric materials have spontaneous polarization.

Reason (R): Above curie temperature, ∈ = for ferro-electric materials.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:

Both A and R are correct. Spontaneous polarization vanishes above ferroelectric curie temperature.

34.
If e is the charge of an electron, R is the radius of its orbit and ω is the angular velocity of electron, the magnetic dipole moment μm of the orbit is |μm| = eωR2.
True
False
Answer: Option
Explanation:

1 μm 1 = 0.5 eωr2.

35.
If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then
tan δ = ∈'∈"
tan δ = 1 - ∈'
Answer: Option
Explanation:

If ∈r" = 0, δ = 0.

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