Showing posts with label part. Show all posts
Showing posts with label part. Show all posts
CHEMISTRY BASICS PART 1 JOSEPH JOHN THOMSON AND AN ATOM
I decided to do the Chemistry basics posts in full details. So,Ill be doing one event per day unless it is completed. Today Im going to explain the concept of an atom as proposed by J J Thomson. (I have a chemistry test today!) Thomson is the scientist whos credited with the discovery of electrons. He was the first one who proposed that atoms are spherical in shape and that electrons are embedded in this spherical body. He explained the model of an atom as that of a Christmas Pudding and that electrons where embedded in it like dry fruits.
Thomson, in 1897, was the first to suggest that the fundamental unit was over 1000 times smaller than an atom, suggesting the subatomic particles now known as electrons. Thomson discovered this through his explorations on the properties of cathode rays Thomson made his suggestion on 30 April 1897 following his discovery that Lenard Rays could travel much further through air than expected for an atom-sized particle. He estimated the mass of cathode rays by measuring the heat generated when the rays hit a thermal junction and comparing this with the magnetic deflection of the rays. His experiments suggested not only that cathode rays were over 1000 times lighter than the hydrogen atom, but also that their mass was the same whatever type of atom they came from. He concluded that the rays were composed of very light, negatively charged particles which were a universal building block of atoms. He called the particles "corpuscles", but later scientists preferred the name electron which had been suggested by George Johnston Stoney in 1891, prior to Thomsons actual discovery.
Thomson, in 1897, was the first to suggest that the fundamental unit was over 1000 times smaller than an atom, suggesting the subatomic particles now known as electrons. Thomson discovered this through his explorations on the properties of cathode rays Thomson made his suggestion on 30 April 1897 following his discovery that Lenard Rays could travel much further through air than expected for an atom-sized particle. He estimated the mass of cathode rays by measuring the heat generated when the rays hit a thermal junction and comparing this with the magnetic deflection of the rays. His experiments suggested not only that cathode rays were over 1000 times lighter than the hydrogen atom, but also that their mass was the same whatever type of atom they came from. He concluded that the rays were composed of very light, negatively charged particles which were a universal building block of atoms. He called the particles "corpuscles", but later scientists preferred the name electron which had been suggested by George Johnston Stoney in 1891, prior to Thomsons actual discovery.
SWITCH Part 1
1.Periappa and switch.
I had two periappas near by my house and their matams were electrified before us. One of them was very social, he used to say- I know one thing of current " If switch is put up, light will go and keep down light will be come " When our houses were electrified, there were three or four lights, which were filament bulbs of different wattage. 60 Watts was felt high. 45 watts was common and certain areas were lighted with 25 watts bulb. Only tumbler switch and wiring was on teakwood reaper and clipping with link clips. Plugs were just inserted to sockets to extend lights temporarily and no switches were there to control supply to socket or plug point. It was considered as a half point for wiring. Today plugs are with switch only unless we ask, and considered as full point.
2. Let us see what is switch and its importance.
Switch in simple language can be defined as an electrical connector. An equipment to connect or disconnect current. When we operate the switch, the PHASE which carry forward current is connected from one point to the other. Electricity is carried by two wires; the second wire is called NEUTRAL. While we operate switch for illuminating a bulb, the electrical circuit is completed via switch for phase to the equipment and NEUTRAL IS ALREADY CONNECTED TO THE LIGHT. We will discuss neutral later.
3. 5 Amps switch.
The day of tumbler switch has gone. Today what we get in market is pressing type switch, better called PIANO switch. (The flush switches, soft switches, photo electric switches etc will be detailed later)
The body of these switches are made by high quality fibre in ISA switches. ISA stands for Indian Standards Organisation. ISA mark means, they have checked the quality and awarded the certificate on the companys application. Earlier they were made of porcelain in Tumbler switches. The metal connector embedded in fibre in the present day switches. In the back of the switch we can see connecting points in metal for the current carrying wire.
4. Switch testing
The typical switch with the metals used is quality tested for thousands of operations and found perfect. Normally once in three or four years it is better to replace the frequently used switch. The switch testing is done mechanically and manually. The method of testing is beyond the scope of this posting. Just for the curious ,the manufacturer test one in hundred switches, for the mechanical test and find the bunch OK – "Oru pana chothukku oru choru patham" is the principle employed.
5. 15 Amps switch.
I had earlier mentioned 5 amps switch. For explaining 15 amps switch, I will first explain what is 5 amps switch.
Amperes is the measurement unit of current. The street voltage supplied by Electricity board in India is 230 volts. This is represented in Physics as V. The current is denoted either as A or I. For simplicity first we will understand even 75 volt is a high voltage. This is the voltage ringing the telephone bell. If you touch the bare end of wires broken and falling while ring come, you will experience it. But it will not harm you like 230 Volts.
5a. Ohms Law
There is a famous and most important law in Physics. It is called OHMS LAW. Yester years we used to say who ever know Ohms law well could be a Telecom Engineer. So much application for the law in Telecommunication…. Now such relay type equipments are phased out.
The law is VOLTAGE X CURRENT = WATTS. Or V x I = W .
W represents wattage. We know there is a marking in our electric iron, washing machine, TV, food cooker etc as xxx watts. For electric iron normally this will be 1000 watts most commonly.
So 1000/ 230 =4.35 A . A five amps switch takes care since it can take a load up to 5 amps.
5.b Water heater switch
But the water heater you can see the wattage as 2000 or 2500 watts. So naturally now we have seen the normal 5 Amps switch is not sufficient. The next category now in market is 15 Amps.
Surely these switches are slightly bigger. Earlier these switches were very big specially made for them. Anchor Company was making them in sandal colour, with special broad switch. We would have operated it for motor, water heaters etc.
Now a day the same flush type is available slightly bigger than 5 amps switch. If load is more it may spark while put on.
6. Water heaters.
About 2 years back there was news about some unfortunate incidents in Chennai with water heater put on and using heated water for bath . It is preferable to keep the heater switch out side than the bathroom so that it can be controlled by others in case of emergency. It is more preferable to switch off the water heater and take bath.
The insulating coil used in water heaters should be periodically checked for insulation and replaced ad safety ensured, then we can very well switch on and take bath, as we take water more water will flow and get quickly heated. Checking and replacing should be done at least ONCE A YEAR.
The cut of switch in the water heater should work efficiently.
7. Ironing
Now a day electric irons with L ED display for cut of are only available. It should be ensured the LED goes on and off, the cord wire not getting heated, cord wire end fixture called plug should have good grip with socket and socket is controlled surely by a switch.
I had two periappas near by my house and their matams were electrified before us. One of them was very social, he used to say- I know one thing of current " If switch is put up, light will go and keep down light will be come " When our houses were electrified, there were three or four lights, which were filament bulbs of different wattage. 60 Watts was felt high. 45 watts was common and certain areas were lighted with 25 watts bulb. Only tumbler switch and wiring was on teakwood reaper and clipping with link clips. Plugs were just inserted to sockets to extend lights temporarily and no switches were there to control supply to socket or plug point. It was considered as a half point for wiring. Today plugs are with switch only unless we ask, and considered as full point.
2. Let us see what is switch and its importance.
Switch in simple language can be defined as an electrical connector. An equipment to connect or disconnect current. When we operate the switch, the PHASE which carry forward current is connected from one point to the other. Electricity is carried by two wires; the second wire is called NEUTRAL. While we operate switch for illuminating a bulb, the electrical circuit is completed via switch for phase to the equipment and NEUTRAL IS ALREADY CONNECTED TO THE LIGHT. We will discuss neutral later.
3. 5 Amps switch.
The day of tumbler switch has gone. Today what we get in market is pressing type switch, better called PIANO switch. (The flush switches, soft switches, photo electric switches etc will be detailed later)
The body of these switches are made by high quality fibre in ISA switches. ISA stands for Indian Standards Organisation. ISA mark means, they have checked the quality and awarded the certificate on the companys application. Earlier they were made of porcelain in Tumbler switches. The metal connector embedded in fibre in the present day switches. In the back of the switch we can see connecting points in metal for the current carrying wire.
4. Switch testing
The typical switch with the metals used is quality tested for thousands of operations and found perfect. Normally once in three or four years it is better to replace the frequently used switch. The switch testing is done mechanically and manually. The method of testing is beyond the scope of this posting. Just for the curious ,the manufacturer test one in hundred switches, for the mechanical test and find the bunch OK – "Oru pana chothukku oru choru patham" is the principle employed.
5. 15 Amps switch.
I had earlier mentioned 5 amps switch. For explaining 15 amps switch, I will first explain what is 5 amps switch.
Amperes is the measurement unit of current. The street voltage supplied by Electricity board in India is 230 volts. This is represented in Physics as V. The current is denoted either as A or I. For simplicity first we will understand even 75 volt is a high voltage. This is the voltage ringing the telephone bell. If you touch the bare end of wires broken and falling while ring come, you will experience it. But it will not harm you like 230 Volts.
5a. Ohms Law
There is a famous and most important law in Physics. It is called OHMS LAW. Yester years we used to say who ever know Ohms law well could be a Telecom Engineer. So much application for the law in Telecommunication…. Now such relay type equipments are phased out.
The law is VOLTAGE X CURRENT = WATTS. Or V x I = W .
W represents wattage. We know there is a marking in our electric iron, washing machine, TV, food cooker etc as xxx watts. For electric iron normally this will be 1000 watts most commonly.
So 1000/ 230 =4.35 A . A five amps switch takes care since it can take a load up to 5 amps.
5.b Water heater switch
But the water heater you can see the wattage as 2000 or 2500 watts. So naturally now we have seen the normal 5 Amps switch is not sufficient. The next category now in market is 15 Amps.
Surely these switches are slightly bigger. Earlier these switches were very big specially made for them. Anchor Company was making them in sandal colour, with special broad switch. We would have operated it for motor, water heaters etc.
Now a day the same flush type is available slightly bigger than 5 amps switch. If load is more it may spark while put on.
6. Water heaters.
About 2 years back there was news about some unfortunate incidents in Chennai with water heater put on and using heated water for bath . It is preferable to keep the heater switch out side than the bathroom so that it can be controlled by others in case of emergency. It is more preferable to switch off the water heater and take bath.
The insulating coil used in water heaters should be periodically checked for insulation and replaced ad safety ensured, then we can very well switch on and take bath, as we take water more water will flow and get quickly heated. Checking and replacing should be done at least ONCE A YEAR.
The cut of switch in the water heater should work efficiently.
7. Ironing
Now a day electric irons with L ED display for cut of are only available. It should be ensured the LED goes on and off, the cord wire not getting heated, cord wire end fixture called plug should have good grip with socket and socket is controlled surely by a switch.
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