Ohm’s Law 

It states, the current passing through any conductor is proportional to the potential difference applied across the conductor provided that physical condition (mechanical strain, temperature) of the conductor remains unchanged. Verification of Ohm’s Law Ohm’s law can be verified by using a simple circuit as shown in fig. aside. A resistance R is connected in […]

Expression for drift velocity 

Consider a section of a metallic conductor of length l and cross-section area A. Let n be the no. of electrons per unit volume of the conductor. Then, volume of the conductor = Al no .of electrons in this volume = nAl Total charge (Q) = nAel; where e is and electric charge. On connecting […]

Mechanism of Conduction of current in metal 

In any metallic conductor large no. of free electrons are available these electrons are in random motion as a result of which their average velocity is zero and there is no net flow of electron so current is zero. When the conductor is connected to a battery, an electric field is setup in the conductor […]

Current Density (J) 

The flow of current per unit area held perpendicularly to the flow of current is called current density. Current density is defined for any point in the conductor. if I current flows across area A then current density is given by The direction of J is along the direction of current. Its unit is ampere/m2.

Current and its direction 

Current The rate of flow of charge in any specific direction is called current. If Q charge flows through a conductor in time t then current is If one coulomb of charge flows through a conductor in one second then the current in the conductor is said to be one ampere. Direction of Current: Before […]

Chemical bonding and shape of molecules | Old is Gold | Class XII 

Very Short Question: (2 marks each)         1.      Predict the structure of methane based on hybridization.         2.      Identify the hybridization of the indicated atom in each of the following molecules: a.       Be in BeF2 b.      B in BF3 c.       N in NH3         3.      Draw […]

Manufacture of Ammonia by Haber’s process 

Theory: NH3 is manufactured by Haber’s process. In this process, pure nitrogen and hydrogen gases react in the ratio of 1:3 by volume in 400°C-500°C temperature, 200-900 atm pressure in presence of iron as catalyst & molybdenum as promoter.                        Fe/Mo (400-500°C)     N2+3H2 ——————–> 2NH3+ […]

Manufacture of Sodium(Na) by Down’s process 

Principle: Down’s cell is a special type of cell that is made for extraction of sodium. During the extraction of sodium metal, following difficulties are seen: a.  Sodium ores like NaCl, Na2CO3 are very stable. b.  The chemical reduction of those sodium salts is not possible since sodium itself is a good reducing agent. c.  The […]

Manufacture of NaOH Caster Kellner’s Process 

Fig: Manufacture of NaOH by Caster Kellener’s Process It consist mercury cathode cell which is a rectangular vessel divided into three compartments by a non-porous slate partition which do not touch the bottom of the cell. A layer of mercury seperates each compartments at the bottom of the cell. One end of the cell is pivoted […]

Polarization | Old is Gold | Class XII 

Polarization Short answers question 1. Can sounds waves be polarized? Explain. 2. Is polarization possible for longitudinal waves? Why? 3. Light waves can be polarized. What about sound waves? Explain. 4. What is polarizing angle? Does it depend on the wavelength of light? 5. The polarizing angle for a transparent medium is 600. What is the refractive index of the […]