We got to see a word ‘hadrons’ above. But what actually are they? As mentioned above, hadrons are composite particles made of quarks. Although individual quarks have fractional electrical charges, they combine such that hadrons have a net integer electric charge. Another property of hadrons is that they have no net color charge even though […]


A quark is an elementary particle and a fundamental constituent of matter. Quarks only exist in groups with other quarks and are never found alone. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Quarks are strongly interacting particles and existence of isolated quark is not discovered so far. There are […]

The Standard Model 

Particle physicists believe that matter is built of twelve types of fundamental particle – the building blocks of the universe. These fundamental particles cannot be broken down any further. Fig: Classification of Elementary Particles according to Standard Model There are two families of fundamental particles- the quarks and the leptons. There are six sorts of […]

Alternating Currents | Old is Gold | XII 

Short Questions 1.      Why do we prefer a choke coil to rheostat in an a.c. current? 2.      What is meant buy independence of an a.c. current? 3.      Why is choke coil preferable to resistor? 4.      Why is choke considered superior to a rheostat? 5.      What do you mean by r.m.s value of an AC current? […]

Electromagnetic Induction | Old is Gold | XII 

Short Questions 1.      What is Lenz’s law? 2.      Mention two types of loss in a transformer. 3.      Show that Lenz’s law is an example of conservation of energy. 4.      Two closely would circular coils have the same number of turns, but one has twice the radius of the other. What is the ratio of self […]

Magnetic Properties of Materials | Old is Gold | XII 

Short Questions 1.      What are magnetic domains? 2.      What is angle of dip? How does it vary from the equator to the poles/ 3.      Define angle of dip and angle of declination at a place. 4.      How does dip vary from place to place on earth`s surface? 5.      Why does a bar magnet not retain […]

Magnetic effect of current | Old is Gold | XII 

Short Questions 1.      Under what conditions does a charge affect a magnet? 2.      State Ampere’s theorem 3.      Does a charged particle moving through a magnetic field experience a force? Express with conditions, maximum, and mini8mum force it experiences. 4.      A portion moving in a straight line enters a strong magnetic field along the field direction. […]

Chemical Effect Of Current | Old is Gold | XII 

Short Questions 1.      What is meant by Faraday’s Constant? 2.      What is the function of copper sulphate used in Daniel cell? 3.      Define one Faraday? 4.      Distinguish between ionic and electronic conduction. Long Questions 1.      State and explain Faraday’s law of electrolysis. Hence define Faraday’s Constant. 2.      State the Faraday’s laws of electrolysis and verify […]

Thermoelectric Effect | Old is Gold | XII 

Short Questions 1.      What do you mean by Peltier`s effect? 2.      What is thermoelectric emf? 3.      Why is Sb-Bi thermocouple preferred to Fe-Cu thermocouple? 4.      What are the factors on which the thermo emf produced in a thermocouple depends? 5.      How is Seebeck effect different from Pektier effect? Explain. 6.      How does thermo emf change […]

Electrical Circuits | Old is Gold | XII 

Short Questions 1.      State Kirchhoff`s laws of circuits. 2.      Why does voltmeter measures current more accurately than an ammeter? 3.      What is Wheatstone bridge? Obtain the balanced condition for the bridge? Explain how resistance can be measured by a meter bridge? Long Questions 1.      What is a Wheatstone bridge? Using Kirchhoff`s law, derive the principle of […]