Difference between Metals, Insulators and Semiconductors

The filament of electric bulb is generally made of tungsten because

When the electrical conductivity of a semi-conductor is due to the breaking of its covalent bonds, then the semiconductor is said to be

Si and Cu are cooled to a temperature of $300 \mathrm{K}$, then conductivity,

Three photo diode $D_1, D_2$ and $D_3$ are made of semiconductors having a bandgap of $2 \mathrm{eV}, 2.5 \mathrm{eV}$  and $3 \mathrm{eV}$ respectively. Which one will be able to detect light of wavelength $4800 \mathrm{\AA }?$

If $N_{\mathrm{p}}$ and $N_{\mathrm{e}}$ be the numbers of holes and conduction electrons in an extrinsic semiconductor, then :-

In insulators the forbidden energy gap between valence band and conduction band is of

What kind of source has conduction current same as displacement current?

Pure silicon and germanium can be used as which of the followng:

Consider semiconductors, now choose the correct statement from the following: 

Identify the wrong statement.

Pure silicon and germanium behave as

Good optical reflectors are conventionally made of

For the metallic conductor

Metals are good conductors of electricity because they contain

Assertion: Conductivity of semiconductor increases with increment in temperature.

Reason: $\alpha$ for semiconductor is negative

Assertion: The average thermal velocity of the electrons in a conductor is zero.
Reason: Direction of motion of electrons are randomly oriented.

Assertion: The electric field inside a charged conductor is zero.

Reason: The charge resides on the outer surface in a conductor.

In a semiconductor

Metals have

Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,