Class 12th

1.4 Glass is basically an amorphous solid. When glass is made the silica is cooled from its liquid state, and it does not solidifies even when the temperature is dropped below freezing point. Hence, glass is a super cooled liquid. Due to this fluidity property, glass can be considered as a liquid of extremely high viscosity. The evidence of the fact can be seen in the windows getting thicker at bottom over a period of time.

As per the NCERT Textbooks

“An integrated Chip consists of many passive and active components fabricated on a single chip of silicon. these ICs are compact, low-cost, and highly reliable. They consume less power and have high speed.”

These ICs are used in majority of our daily use electronics and all advance electronics. 

1.3 Amorphous solids: Amorphous solids are solids in which the geometry of the solid is said to be irregular. When the amorphous solids are cut with a knife, a clean surface is not obtained. The amorphous solids are called pseudo solids or sometimes also as super cooled liquids. Polyurethane, Cellophane, Polyvinyl Chloride, Fiberglass, Teflon.

Crystalline solids: Crystalline solids are solids in which the geometry of the solid is said to be regular. When the Crystalline solids are cut with a knife, a clean surface is obtained. Crystalline solids are also called true solids.Naphthalene, Benzoic acid, Potassium nitrate, and Copper

1.2 They are rigid so the intermolecular forces of attraction that are present in solids are very strong. Hence, solids have a definite volume.

1.1 : It is because of the lack of mobility which makes a solid rigid. Since the atoms are almost lacking in mobility, their kinetic energy is negligibly small. The constituent particles in solids are held together by strong inter-atomic forces. The average location of the particles in a lattice does not change with time.

2.35 According to Gauss's law, the electric field between a sphere and a shell is determined by the charge $q_1$ on a small sphere. Hence, the potential difference, V, between the sphere and the shell is independent of charge $q_2$ . For positive charge $q_1$ , potential difference V s always positive.

2.34 Equidistant planes parallel to the x-y plane are the equipotential surfaces.

Planes parallel to the x-y plane are the equipotential surfaces with the exception that when the planes get closer, the field increases

Concentric spheres centered at the origin are equipotential surfaces.

A periodically varying shape near the given grid is the equipotential surface. This shape gradually reaches the shape of planes parallel to the grid at a larger distance.

2.32  Length of the co-axial cylinder, l = 15 cm = 0.15 m

Radius of the outer cylinder, $r_1$ = 1.5 cm = 0.015 m

Radius of the inner cylinder, $r_2$ = 1.4 cm = 0.014 m

Charge on the inner cylinder, q = 3.5 $\mu C=3.5*{10}^{-6}$ C

Capacitance of a co-axial cylinder of radii $r_1$ and $r_2$ is given by the relation

C = $\frac{2\pi {\epsilon }_{0}l}{{\log }_e?\frac{r_1}{r_2}}$ , where ${\epsilon }_0$ = permittivity of free space = 8.854 $*{10}^{-12}$ $C^2{N}^{-1}$ $m^{-2}$

C = $\frac{2\pi *8.854\mathrm{}*{10}^{-12}*0.15}{{\log }_e?\frac{0.015}{0.014}}$ = 1.21 $*{10}^{-10}$ F

Potential difference of the inner cylinder is given by

V = $\frac{q}{C}$ = $\frac{3.5*{10}^{-6}}{1.21\mathrm{}*{10}^{-10}}$ = 2.893 $*{10}^4$ V