ODISHA CLASS 9

1. Electric Charges Definition : Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electric and magnetic field. There are two types of charges: positive (+) and negative (-). Unit : The SI unit of charge is the coulomb (C) . 2. Conservation of Charge Principle : The total charge in an isolated system remains constant over time. Charge cannot be created or destroyed, only transferred between bodies. Implication : This principle is a fundamental law of nature, ensuring that charge is conserved in all processes. 3. Coulomb’s Law – Force Between Two Point Charges Statement : Coulomb's law gives the force between two point charges. It states that the force between two charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. Mathematically: F = k e ∣ q 1 q 2 ∣ r 2 F = \frac{k_e |q_1 q_2|}{r^2} where: F F is ...

  Diamond and graphite are — allotropes . Diamond is — co-valent solid. Number of atoms per unit cell: Face-centred cubic (FCC) = 4 atoms Body-centred cubic (BCC) = 2 atoms Radius ratio for an ion to occupy tetrahedral site is between 0.225 to 0.414 . Isotropy refers to the property of a material where its physical properties are identical in all directions. Anisotropy refers to the property of a material where its physical properties vary with direction. Unit cell of a crystal is the smallest repeating unit of a crystal structure that, when repeated in space, forms the entire crystal. Interstitials are atoms or ions that occupy spaces (interstices) between the regular lattice positions in a crystal. Types of lattice imperfections found in crystals are: Point defects (vacancies, interstitials, and substitutional defects) Line defects (dislocations) Planar defects (grain boundaries) Crystal lattice is a three-dimensional arrangement of points (atoms, ions, or molecules) in...