Physics-Important Points-One Liners
1-The process of heat transmission in the form of electromagnetic waves is called radiation. It does not require any medium for propagation.
2-A body that absorbs all the radiation incident on it is called a perfectly black body.
3-A force which changes the configuration of a body is called a deforming force
4-The property of a body by virtue of which it does not regain its original configuration after the removal of deforming force is called plasticity.
5-A substance which begins to flow under an external force is called a fluid. Liquids and gases are fluids
6- Hydrometer- It is an instrument used to measure density or relative density of the liquid. Its working is based on the law of floatation.
7-Aneroid barometer is used to measure atmospheric pressure and height of a place
8-When a body is partially or wholly immersed in a liquid, an upward force acts on it, which is called buoyant force or upthrust and this property of fluids is called buoyancy
9-Archimedes Principle– When a body is partially or completely immersed in a quid, it loses some of its weight. The loss in weight is equal to the weight of the liquid displaced by the submerged part of the body.
10-The phenomenon of rising or falling of liquid column in a capillary tube ( a glass tube of very fine bore) is called capillarity.
11-The property of a liquid by virtue of which it tries to minimise its free surface area is called surface tension
12-Viscous force: The force which opposes the relative motion between different layers of liquid or gases is called viscous force.
13-Stoke’s Law– According to this law, the viscous force depends upon the coefficient of viscosity, velocity of the moving object and its size.
14-The electricity produced by friction between two appropriate bodies, is called static electricity, it is also called frictional electricity
15-The space in the surrounding of any charge in which its influence can be experience by other charge, is called electric field.
16-An electric cell is a device which converts chemical energy into electrical energy.
17-A current-carrying coil containing a soft iron core, is called an electromagnet. It is utilised in electric bell, telegraph receiver, telephone diaphragm, transformer, dynamo etc.
18-The electrical energy produced or consumed per unit time is called electric power.
19-An ammeter is an instrument used to measure electric current. It is always connected in series. The resistance of an ideal ammeter is zero
20-Lenz’s Law– The direction of induced emf or induced current is always in such a way that it opposes the cause due to which it is produced.
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