Monthly Archives: March 2014

SSC REVISION POINTS AND IMPORTANT NOTES OF NCERT

Radioactivity
The phenomenon of spontaneous emission of radiation by heavy element is called radioactivity and the element which show this phenomenon are called radioactive element.



Alpha particle
An alpha particle is a helium nucleus having two neutron and two proton.when electron orbiting around the nucleus of helium atom are knocked out completely we get a double ionised helium atom called alpha particle.

Beta particle
A beta particle is a fast moving electron.

Gama particle
Gama particle are packet of electromagnetic radiation and are known as photons.they do not have any charge and their rest mass is zero.

SSC IMPORTANT NOTES

Protons
Positive charge of an atom is concentrated in the nucleus due to positive charge particle called proton.
Properties
1.   It is constituent of nucleus
2.   It is positively charge particle.
3.   The number of proton in the nucleus is called atomic number.

Neutron
The uncharged particle or neutral particle present in the nucleus of an atom are called as neutron.



Properties
1.   Neutron is a constituent of nucleus.
2.   Neutron is a neutral particle i.e it has no charge.
3.   Neutron has very high penetrating power.
4.   A free neutron is unstable.

Isotopes
An atom of an element having same atomic no. but different mass no. is called  as isotopes.

Isobar
The atom of element having same mass no. but different atomic no. are called isobar.

Isotones

Isotone are the nuclides which contain the same no. of neutron.

SSC SCIENCE STUDY MATERIAL

Law of photoelectric emission

1.   For a given metal and frequency of incident light the no. of photoelectron ejected per second is directly proportional to the intensity of incident light.

2.   For a given metal there exist a minimum frequency of incident light below which no emission of photoelectron take place called as threshold frequency.

3.   The photoelectric emission is an instantaneous process.

4.   The maximum K.E is independent of the intensity of incident light.
Einstein photoelectric equation




Acc. To Einstein when photon of energy fall on the metal surface the energy of the photon is absorbed by the free electron in a metal.

Critical frequency

It is defined as the highest frequency which when sent straight toward ionosphere get reflected from the ionosphere and return to the earth.

Reading all those points will help you remember important points which
will help in easy and quick answer of the SSC general knowledge
questions or other competitive exam

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SMART GUESSES THAT CAN COME IN SSC EXAMS,UPSC PRELIM


Hertz observation
Hertz observed that spark jump more readily when the detector was exposed to ultraviolet light this observe lead to him to conclude that light fluctuated the emission f charge from metallic sphere.

Lenard’s observation
He observed that when ultraviolet light was allowed to fall on a metallic electrode C electron were emitted by it these electron are attracted toward an electrode A maintained at positive potential thus the electric current began to flow in the circuit.

Cut of potential or stopping potential
The minimum negative potential we not applied to plate A for which photoelectric current become zero is called as cut of potential or stopping potential.

Threshold frequency

The minimum value of frequency of the incident light below which photoelectric emission is not possible is called as threshold frequency.

Reading all those points will help you remember important points which will help in easy and quick answer of the SSC general knowledge questions or other competitive exam

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QUESTION OF PHYSICS THAT CAN COME IN SSC

Solar cell
A p-n junction diode which convert solar energy into electrical energy is known as solar cell.

Work function
The minimum energy required by the free electron to just leave the metal surface is called as work function.

Electron emission
The phenomenon of emission of electron from a surface of metal is called a electron emission.

Type of electron emission
1.   thermodynamic emission
it is a phenomenon of emission of electron from metal surface when heated suitable.

2.  Photo electric emission 
It is a phenomenon of emission of electron from the metal surface when light radiation of suitable frequency fall on it.

3.   Field emission
It is the phenomenon of emission of electron from the metal surface under the application of strong electric field.

4.   Secondary emission
It is the phenomenon emission of electron from the metal surface when fast moving electron strike the metal surface.

Photoelectric effect

The phenomenon of emission of electron from the metal surface when exposed to light energy of suitable frequency is called as photoelectric effect.

SSC SCIENCE QUESTIONS THAT CAN COME + NCERT NOTES

Zener diode
A heavily doped p-n junction diode which work  in the break down region is called a zener diode.

Zener diode as a voltage regulator

A zener diode can be used as voltage regulator or voltage stabilizer to provide a constant voltage from a source whose voltage may fluctuate over a wide range.when the input voltage is increase resistance of zener diode decrease and hence the current through the diode increase to high value
As a result of this large voltage drop occurs across the dropping resistance R.hence the output voltage across RL is maintain to the desire value.when the input voltage decrease through the diode also decrease.so now small voltage drop take place across the resistance R and the output voltage across RL is maintain at the desire constant value.

NCERT NOTES FOR SSC {REVISION POINTS}


Eddy current

The induce circulating current produce in a conductor itself due to change in magnetic flux linked with the conductor is called eddy current.

Disadvantage of eddy current
1.the production of eddy current in a metallic block leads to the loss of electrical energy.in the form of heat.
2.the heat produce due to eddy current breaks the insulation used in the electrical machine.

Impedance               
The impedance of L.C.R circuit is define as the total effective a position offered by a circuit to flow of ac.

Electrical resonance
It is said to be take place in L.C.R circuit when the circuit is allow the maximum current for a given frequency of the alternative source for which the inductive resistance become equal to the capacitance resistance.

Metals
The solid having very low value of resistivity or very high value of conductivity are called as metal.

Insulators
The solid having very high value of resistivity or low value of conductivity are called insulators.

Photons

Photons are the packets of energy which are emmited by a source of radiation.


Reading all those points will help you remember important points which
will help in easy and quick answer of the SSC general knowledge
questions or other competitive exam

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SSC SCIENCE SECTION {IMPORTANT POINTS TO GAIN MARKS}


Electric energy
Work done by a source to maintain current in an electrical circuit is called an electric current.

Electric power
Electric power can be defined as rate of doing electrical work.

Cells
A cell is a electrical device which provides the necessary potential difference in an electrical circuit to maintain the flow of current.

Emf (electro motive force)
Emf of the may be defined as the potential difference between its terminal when no current is drawn from the cell.

Magnetic flux
Magnetic flux through any surface is define as a total number of magnetic field line passes through the surface.

Faraday law

1st law
Whenever there is a change in magnetic flux linked with a coil an emf induce in the coil this emf is as long as there is change in magnetic flux.

2nd law

The magnitude of induce emf is directly proportional to the rate of change of magnetic flux linked with a coil.

SSC SCIENCE SECTION [IMPORTANT REVISION POINTS]

Ohm’s law
The current flowing through the conductor is directly proportional to the potential difference across its end provides the external condition like temperature,pressure remain constant.

Resistance
The hindrance offered by the conductor in the flow of current is called as resistance.
S.I unit ohm.

Conductivity
Conductivity is defined as the inverse of resistivity.

Limitation of ohms law
1.change in nature of material occur with passage of current.
2.increase of current possible of decrease in voltage.
3.decrease of current is possible decrease in voltage.

Ohmic and non ohmic conductor
The conductor which obeys ohms law is called ohmic conductor.

The conductor which do not obeys the ohms law is called non ohmic conductor.