Q. Assertion (A): The regular or irregular stacking of atoms has importanteffect on properties of materials.

Reason (R): The arrangement of atoms in a given material can be studied using X-rays.

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Q. The probability of recombination of electrons and holes in a semiconductor is proportional to

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Q. For iron, the ferromagnetic Curie temperature is

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Q. Assertion (A): Both sodium and ferrous are ferromagnetic.

Reason (R): Both sodium and ferrous have body centred cubic structure.

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Q. A photoconductor is a

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Q. The amount of time between the creation and recombination of a free electron and hole is called

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Q. As per Curie-Weiss law, the magnetic susceptibility of a material varies as

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Q. If ∈ᵣ = ∈ᵣ' - j∈ᵣ" tan δ = ∈ᵣ'/∈ᵣ".

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Q. The materials having low retentivity are suitable for making

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Q. Assertion (A): Drift velocity of electrons is proportional to the applied electric field E.

Reason (R): The average drift velocity per unit field is called mobility.

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Q. Transformer oil is

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Q. In a valence crystal, the valence electrons

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Q. Lines of magnetic field attract each other.

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Q. Resistivity of copper is lower than that of nickel. When a small percentage of copper is added to nickel, the resistivity

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Q. In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel.

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Q. A parallel plate capacitor having C = 200 x 10¯¹² F has loss dielectric having tan δ = 4 x 10¯⁴. At an ac voltage of f = 10⁶ Hz and peak value 2 V, the dielectric losses are

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Q. As regards dielectric constant εr

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Q. When temperature is more than ferromagnetic curie temperature, the behaviour of a ferromagnetic material is similar to that of paramagnetic material.

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Q. Assertion (A): ∈₀ has the dimensions of farad per meter.

Reason (R): D = ∈₀∈ᵣ E.

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Q. The number of valence electrons in germanium atom is

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