05-01-2018, 04:28 PM
Power
*The rate of doing work is known as Power. Power (P) = Work done / Time
*Unit of measurement of power is - Horse power
*Joule /sec= 1 watt
*1 horse power = 746 watts
*1 kilowatt = 1000 watts
*1 megawatt =1000000 watts
Freely falling
*When an object falls towards the earth under gravity in the absence of air resistance is called freely falling body.
*All objects in free fall near the earth have same acceleration.
*The acceleration of an object in free fall is independent of its
Ans : Mass
Terminal Velocity
*Terminal Velocity is the highest velocity attainable by an object as it falls through air.
*At some speed, the force of resistance will be equal to the gravitational pull on the object. At this point the object ceases to accelerate and continues falling at a constant speed is called terminal velocity.
ELECTRICITY
*The flow of electrons is
Ans : Electricity
*Properties of Electricity
Ans : Electric charge, Electric current, Electric field, Electric potential, Electro magnetism
*Electric charge was first observed in a substance called
Ans : Amber
*Fundamental quantity of electricity
Ans : Charge
*Unit of electric charge
Ans : coulomb
*1 coulomb = 6.25 x 1018 electrons
*Charge of an electron is 1.6 x 10-19C
*Electric current is the flow of electrically charged particles through a medium.
Current = Charge/Time
*Unit of flow of electric current - Ampere.
*Electric field is the region which surrounds the electrically charged particles.
Michael Faraday
*Father of Electricity
Ans : Michael Faraday
*Law of electrolysis was formulated by
Ans : Michael Faraday
*The concept of an electric field was introduced by
Ans : Michael Faraday
*Dynamo was invented by
Ans : Michael Faraday
*Electro magnetic Induction was discovered by
Ans : Michael Faraday
*Electrolysis is the process of splitting up of a chemical substance when an electric current flows through it.
*Substance used for electrolysis are - electrolytes.
eg: Sodium Chloride, Potassium Chloride, Hydrochloric acid.
*Electrical conductivity of an electrolyte increases with the rise in temperature. Instrument that regulates the resistance or current in a circuit - Rheostat
*Electric potential is the capacity of an electric field to do work on an electric charge.
*Electro magnetism is the force that causes the interaction between the magnetic field and the electrically charged particles.
*Electro magnetism was discovered by Hans Christian Oersted (1820).
*Negatively charged particles gain electrons.
*Positively charged particles lose electrons.
*The stationary electric charge built up on a material is called
Ans : Static Electricity.
*Electricity that can flow from one point to another through the conductors, cables etc. is called
Ans : Dynamic Electricity (current electricity)
*Dynamic electricity is of two types.
1.Alternating current (AC)
2.Direct Current (DC)
*Alternating current (AC) is the continuous How of current.
*It reverses its direction and magnitude with respect to time.
*Direct Current (DC) is the unidirectional flow of electric charge.
*It does not reverse its direction with respect to time.
*Batteries, solar cells, thermocouples etc produce DC.
*DC was formerly known as Galvanic current.
*AC is used more widely than DC.
*The advantage of AC over DC is, it can be transmitted over long distances with minimum power loss.
*The device which conducts DC but blocks AC is Inductor.
Conductors and Insulators
*The substances which easily allows electricity to flow through them is called Conductors, eg: Metals, graphite, animal bodies and earth.
*The best conductor of electricity is Silver, as it has the least resistance.
*Copper and Aluminium are the metals commonly used in electrical circuits.
Energy Conversion
*Electric Fan -Electrical to Mechanical energy
*Electric bell -Electrical to Sound energy
*Solarcell -Solar to Electrical energy
*Electric bulb -Electrical to Light energy and Heat energy
*Battery -Chemical to electric energy
*Electric oven -Electrical to Heat energy
*Dynamo-Mechanical to Electrical energy
*Motor-Electrical to Mechanical energy
