S.N Valve S.N Transistor 1. The charge carriers of valves are electrons. 1. The carriers of the transistors are the electron and holes. 2. In a valve the charge carries are provided by heater called hot cathode. 2. In a transistor, charge carriers are provided by emitter. No heater or heating elements are required. 3. … Read more
A) Diamagnetic Substances and its characteristics Diamagnetic substances are those substances which, in their normal states, have no magnetic moment at all. Antimony, Bismuth, Copper, Gold, Mercury, water, alcohol, Hydrogen are diamagnetic substances. Characteristics They are feebly repelled by magnet and magnetic field. When placed in a magnetic field, they all are weakly magnetized in … Read more
A) α-radiation The α-rays are not rays, but consist of a stream of positively charged particles, having 2 units of positive (+) charge, and 4 units of mass. Thus, α-particles are doubly ionized helium atoms i.e., He2+. The α-particles emitted by any radioactive source are shot out with high velocity. The initial velocity depends on … Read more
When a solid object is immersed in a fluid, an upward force acts on it. The magnitude of the force is given by Archimede’s principle. This principle was propounded by Archimedes (287- 212 BC), a famous Greek scientist. Archimede’s principle states , “ When a body is partially or wholly immersed in a fluid, it … Read more
The disorder in which a person cannot see nearby or distant objects clearly is called defect of vision. There are two most common defects of vision. They are: a)Myopia It is the defect of vision in which a person can see nearby objects clearly but cannot see distant objects. It is also called short sightedness … Read more
It is a device that converts high voltage AC to low voltage AC of the same frequency and vice versa. It works on the principle of mutual induction, i.e., whenever the current (magnetic flux) through a coil changes, an e.m.f. is induced in the neighbouring coil. According to this principle, when the electric current in … Read more
S.N Alternating current Direct current 1. The current which changes magnitude and polarity is called alternating current. The current which does not change magnitude and polarity is called direct current. 2. It is produced by AC generator, dynamo, etc. It is produced by cells, battery, DC generator, etc. 3. It can be used in transformer … Read more
S.N Convex lens Concave lens 1. It is thick in the middle but thin at the edges. It is thin in the middle but thick at the edges. 2. It converges the parallel rays of light falling on it. It diverges the parallel rays of light falling on it. 3. It has a real focus. … Read more
S.N Heat Temperature 1. It is a form of energy which gives us sensation of warmth. It is a measure of degree of hotness or coldness of body. 2. It is the cause of change in temperature. It is the effect of heat. 3. It is measured by calorimeter. It is measured by thermometer. 4. … Read more
S.N Mass Weight 1. The amount of matter contained in a body is called mass. The force by which earth attracts or pull objects towards its center is called weight. 2. It remains always constant regardless of the location in universe. It varies from place to place. 3. It is measured by ordinary or beam … Read more