9th 10th
Doping, N-Type, P-Type Semi-Conductors (Physics-19.4,5,6)
Doping 19.4 A semi-conductor, in its purest form is not such a good conductor, so it is of little practical value. But it can be rendered useful by increasing the number of holes and free electrons according to our requirement. This is done by adding specified quantities of a trivalent or a pentavlent atoms as [...]
Semi Conductor (10th-Physics-Lesson-19.3)
The material objects, on the basis of electrical properties, are classified in three groups: Conductor The substances in which electric current flows easily are called conductors. Usually, metals are good conductors. For example gold, silver, copper, aluminum and other metals. Our body is also a good conductor of electricity. Earth is also a very big [...]
Radiation Hazards (10th-Physics-Lesson-18.7)
We have already read that radiations are very useful in many ways for mankind. Radiations are being used in different ways in medical, agriculture and in some industrial units, but there is always danger of radiation hazards due to carelessness in its use. The problem is that these radiations are not visible and their adverse [...]
Nuclear Fission (10th-Physics-Lesson-18.6)
In 1938, Ottohann and Stresemann bombarded slow neutrons on uranium. As the neutron is a neutral particle, so it was expected that the uranium nucleus will absorb the neutron and become a heavy uranium nucleus. But what happened was, that the uranium nucleus itself broke into two equal parts. In this process two or three [...]
Uses of Radio Isotopes (10th-Physics-Lesson-18.4)
18. 4 Uses of Radio Isotopes Although, all the isotopes of an element chemically behave identically, but every isotope emits specific radiations due to which it is easy to identify an isotope. It is this characteristic due to which the isotopes are being used in different fields of our life. Uses in agriculture If the [...]
Half Life (10th-Physics-Lesson-18.3)
We have already studied that radioactive elements continuously emit radiations, due to which they change into new elements. For example if an a particle is emitted by an element . The atomic mass number of the newly produced element remains the same, but its charge number increases by one unit. It is due to the [...]
Natural Radioactivity (10th-Physics-Lesson-18.2) Part 2
Experiment A small quantity of the radioactive source was placed in a hole dug in a block of lead (fig. 18.1) so that parallel rays ma come out of the nosal at S. A photographic plate was placed at some distance above the block so that all the radiations fall on this plate. All of [...]
Self Induction (10th-Physics-Lesson-17.8)
The number of lines of force in a magnetic field depends upon the strength of the field. A stronger field has more lines than a weaker one. interesting information how some birds, like pigeon, correctly estimate the direction? there is some sort of natural magnet in their head. We have read that as current passes [...]
Mutual Induction (10th-Physics-Lesson-17.7)
Fig. 17.19 shows two coils X and Y, placed close to each other, the coil X has been connected with a battery and a switch, whereas a sensitive galvanometer is connected with the coil Y. we observe that as soon as the switch of the coil X is closed, the galvanometer connected with the coil [...]
A.C. Generator (10th-Physics-Lesson-17. 6)
If a coil is rotated in a magnetic field, the magnetic flux passing through it would be maximum when its position is perpendicular to the lines of force (fig. 17. 15 a) and the flux would be zero (fig 17. 15b) when its plane is parallel to the lines of force because in this position, [...]
