Both Jupiter and Saturn have days that last about 10 hours. Jupiter has a period of 0.410 earth days or about 9.84 hours and Saturn has a period of 0.426 earth days or about 10.224 hours.
Which planet rotates so fast that its day is only 10 hours long?
Both Jupiter and Saturn have days that last about 10 hours. Jupiter has a period of 0.410 earth days or about 9.84 hours and Saturn has a period of 0.426 earth days or about 10.224 hours.
What is the Astronomical Unit?
When describing distances on the scale of our Solar System, conventional units of measure are not conveniently sized. Miles are too small, and light years are too large, to permit easily compared numbers. For example, the distance between the Sun and Earth is about 93,000,000 miles; between the Sun and Pluto is about 3,700,000,000 miles. Comparing those two numbers, it is not easily seen that Pluto is about 40 times as far from the Sun as Earth is.
The Astronomical Unit (AU) represents a distance of Earth's average distance to the Sun, or about 93,000,000 miles.
How did planet Neptune get its name?
In Roman mythology Neptune was the god of the Sea.
After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. An international dispute arose between the English and French (though not, apparently between Adams and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Le Verrier diverge from Neptune's actual orbit fairly quickly. Had the search for the planet taken place a few years earlier or later it would not have been found anywhere near the predicted location.
Read more.....
What is the hottest part of Sun?
The center of the sun is the hottest part (at around 15 million Kelvins, or 27 million degrees Fahrenheit). The temperature then drops to 5,800 K (10,000 degrees F) at the visible surface, although the corona (the part just above the surface, where solar flares are), can get much hotter (2 million K, or 3.6 million degrees F).
What is the difference between cathode rays and beta rays?
cathode 'rays' were observed in electrical
experiments because of their fluorescent effect near a negatively charged plate (called the
cathode) in a vacuum. They were only later found to be negatively charged electrons emitted
from negatively charged plates and accelerating toward positively charged ones. (Like
charges repel, unlike charges attract.)
Beta 'rays' were first observed being emitted from certain unstable (radioactive) isotopes, and behaved unlike the alpha and gamma radiation also found in radioactivity. It wasn't until later that both alpha and beta 'radiation' were discovered to actually be particles; only gamma rays consist of true electromagnetic radiation. Beta 'rays' are actually electrons ejected from decaying neutrons, and are now more often referred to as Beta emission or Beta particles.
So electrons can be described differently, not based on WHAT they are but HOW they are created or observed.
Beta 'rays' were first observed being emitted from certain unstable (radioactive) isotopes, and behaved unlike the alpha and gamma radiation also found in radioactivity. It wasn't until later that both alpha and beta 'radiation' were discovered to actually be particles; only gamma rays consist of true electromagnetic radiation. Beta 'rays' are actually electrons ejected from decaying neutrons, and are now more often referred to as Beta emission or Beta particles.
So electrons can be described differently, not based on WHAT they are but HOW they are created or observed.
How fast do electrons travel when moving as an electrical current through copper wire?
The actual velocity of electrons through a conductor is
measured as an average speed called drift velocity. This is because
individual electrons do not traverse straight
line paths in conductors, instead they move in a random zig-zag motion, changing
directions as they collide with atoms in the conductor. Thus, the
actual speed of the electrons through the conductor is very
small in the direction of current.
For example, the drift speed through a copper wire of cross-sectional area 3.00 x 10-6 m2, with a current of 10 A will be approximately 2.5 x 10-4 m/s or about a quarter of a milimeter per second.
For example, the drift speed through a copper wire of cross-sectional area 3.00 x 10-6 m2, with a current of 10 A will be approximately 2.5 x 10-4 m/s or about a quarter of a milimeter per second.
What is Plasma?
A plasma (or, more properly, an electromagnetic plasma) is a phase of matter that has enough energy for the electrons to separated from the nucleus. It consists of independently moving electrons and nuclei, and thus has some rather interesting properties, such as very good magnetic shielding. It can be found in places such as the center of the sun, and also, in small quantities, surrounding a lightening bolt.
Many people consider solid, liquid, gas and plasma to be the only four phases of matter. This is not true, as there exist many others, but they are generally more exotic with names like hadron gas or Bose-Einstein Condensate.
How did atom obtain its name?
The word is derived from the Greek word "atomos", meaning indivisible. The concept of the atom originated round 440 BC. In Greek, the prefix "a" means "not" and the word
"tomos" means cut. Word "atom" therefore comes from "atomos", a Greek
word meaning uncuttable.
In 1803, John Dalton formulated the "atomic theory" of matter based on experiments that quantified the weights of elements formed when compounds were broken down. Based on experimental evidence, Dalton proposed that atoms really do exist as fundamental units of all elements.
Twentieth century physics was able to probe atoms and prove that they are not, in fact, indivisible. But the name stuck, and still has meaning in that atoms are the smallest, indivisible part of any element. If you do divide them into smaller pieces of protons, neutrons and electrons, you no longer have the original element.
In 1803, John Dalton formulated the "atomic theory" of matter based on experiments that quantified the weights of elements formed when compounds were broken down. Based on experimental evidence, Dalton proposed that atoms really do exist as fundamental units of all elements.
Twentieth century physics was able to probe atoms and prove that they are not, in fact, indivisible. But the name stuck, and still has meaning in that atoms are the smallest, indivisible part of any element. If you do divide them into smaller pieces of protons, neutrons and electrons, you no longer have the original element.
What is Dry Ice?
Dry ice is nothing but solidified Carbon Dioxide (CO2). When Carbondioxide is cooled to a very low temperature it transforms into solid. The temperature is about -78 deg centigrade.
Carbon Dioxide is an interesting material because, at normal atmospheric pressures, it has no liquid state. It can only obtain a liquid state under very high pressure in a containment vessel.
So, when you have a frozen chunk of carbon dioxide out in the open where you can see it, it will transform directly from its solid state to a gas state with no intermediate liquid state. This process is known as 'sublimation'.
Dry ice freeze water vapor in the air near it producing visible vapor all by itself, however adding water will also add substantial heat which will cause the solid CO2 to sublimate at a greatly accelerated rate thus producing much more visible vapor.
Carbon Dioxide is an interesting material because, at normal atmospheric pressures, it has no liquid state. It can only obtain a liquid state under very high pressure in a containment vessel.
So, when you have a frozen chunk of carbon dioxide out in the open where you can see it, it will transform directly from its solid state to a gas state with no intermediate liquid state. This process is known as 'sublimation'.
Dry ice freeze water vapor in the air near it producing visible vapor all by itself, however adding water will also add substantial heat which will cause the solid CO2 to sublimate at a greatly accelerated rate thus producing much more visible vapor.
What is Heavy water?
Normal water is made of two Hydrogen atoms and one Oxygen atom. Hydrogen atom and Oxygen atoms are covalently bonded
together. Normal water is designated by H2O.
Heavy water also has same molecular structure but Hydrogen atoms are replaced by isotopes of Hydrogen called 'Deuterium'. Standard hydrogen has one Proton in its nucleus (Relative Molecular Mass = 1), Deuterium has one Proton and one Neutron in it nucleus, (Relative Molecular Mass = 2). Hence it is 'heavier' than normal hydrogen. This leads to the water being heavier.
Heavy water also has same molecular structure but Hydrogen atoms are replaced by isotopes of Hydrogen called 'Deuterium'. Standard hydrogen has one Proton in its nucleus (Relative Molecular Mass = 1), Deuterium has one Proton and one Neutron in it nucleus, (Relative Molecular Mass = 2). Hence it is 'heavier' than normal hydrogen. This leads to the water being heavier.
What is Boyles Law?
Boyle's Law is a statement of the relationship
between the pressure and volume of gasses. Specifically it states that
under isothermic conditions, i.e. when temperature remains constant, the product of the pressure and volume
remains constant, or
P1 x V1 = P2 x V2
where P1 is the pressure before some change, V1 is the volume before the change, P2 and V2 are the new values after the change.What are the differences between jet airplanes and rockets?
Newton's third law of motion holds good for motion of both jet air planes and rocket engines. They move by
expelling hot gases opposite to the direction of desired acceleration. The momentum imparted to the gases is exactly
opposite to the momentum imparted to the vehicle.
The biggest difference between a jet engine and a rocket lies in their propulsion systems.
A jet engine works like this: It sucks in air from the front of the engine. This air is burned with the fuel within the engine. The resulting large mass of gas is ejected towards the rear at high velocity, which both propels the airplane forward, and gets more air sucked into the engine. In normal flight, the engines are used to propel the airplane forward. The actual 'uplift' is gained through the wings using the strong flow of the wind.
A rocket, in contrast, carries both fuel (which may be solid or liquid) and oxygen. Therefore it does not suck in air from the front. All it does is burn the fuel with the oxygen, and eject it at very high velocities backward. This momentum is used to both lift and propel the rocket. There are no wings for uplift. Any wings are for steering purposes.
In a nut shell, rocket carries its own supply of oxygen for combustion. A jet engine requires oxygen from the atmosphere for combustion, and so cannot operate in the vacuum of space.
The biggest difference between a jet engine and a rocket lies in their propulsion systems.
A jet engine works like this: It sucks in air from the front of the engine. This air is burned with the fuel within the engine. The resulting large mass of gas is ejected towards the rear at high velocity, which both propels the airplane forward, and gets more air sucked into the engine. In normal flight, the engines are used to propel the airplane forward. The actual 'uplift' is gained through the wings using the strong flow of the wind.
A rocket, in contrast, carries both fuel (which may be solid or liquid) and oxygen. Therefore it does not suck in air from the front. All it does is burn the fuel with the oxygen, and eject it at very high velocities backward. This momentum is used to both lift and propel the rocket. There are no wings for uplift. Any wings are for steering purposes.
In a nut shell, rocket carries its own supply of oxygen for combustion. A jet engine requires oxygen from the atmosphere for combustion, and so cannot operate in the vacuum of space.
How does ice form on a window pane in winter?
Its is related to "relative humidity", which is a
measure of the amount of actual water vapor in the air compared to the
maximum amount of water vapor the air can
hold at a particular temperature. Warmer air can support more water vapor than cold air. As warm
air comes in contact
with a cold window pane, it's temperature is lowered and the water vapor
that it can no
longer hold condenses. If the temperature of the pane is below 0°C
(32°F). that water
freezes to become ice on the window pane.
What is outgassing in vacuum science?
The generation of gas resulting from the desorption is known as
outgassing. The outgassing constant is defined as the rate at which gas appears
to emanate from unit area of surface, and is usually measured in units of
Torr.Liter.Sec-1.Cm-2.
If the temperature of the material is raised (baking), the outgasssing
rate rises to a peak value.
Together with the acceleration of desorption, heating may also have the
effect of causing activated chemisorption of physically adsorbed gas (in
particular water vapour), which can then be desorbed only by prolonged heating
at much high temperatures.
Chemi-adsorbed water vapor continues to be evolved at temperatures in
excess of 300 degC. It should therefore appear that a degassing programme should
begin with pumping at room temperature to remove physically adsorbed water
vapor, before baking is commenced.
What is desorption?
When
a material is placed in Vacuum, the gas which was previously adsorbed begins to
desorb i.e. to leave the material.
The
desorption is influenced by
1.
Pressure
2.
Temperature
3.
Shape of material
4.
Kind of its surface
The pressure has a basic influence on the desorption phenomenon since
according to its tendency of increasing over or decreasing below the
equilibrium , the phenomenon of sorption or that of desorption appears.
The temperature has a clear influence on desorption phenomena. Desorption
is endothermic, thus it is accelerated by increase of temperature.
The shape of the material influences desorption either if the gas is
adsorbed or absorbed.
If the gas is adsorbed, then only the amount of surface is the influencing
factor, but if the gas has to diffuse from the interior of the material to the
surface, then the third dimension “thickness” is also influencing the rate of
desorption.
ABOUT ELECTROLYTIC CAPACITORS
They
provide more capacitance for their size than any other type. Electrolytics all
have one thing in common, instead of usual plates separated by a dielectric,
the electrolytic capacitor has a metallic anode coated with an oxide film. This
outer covering is the dielectric, and a liquid electrolyte acts as a cathode. A
second metallic conductor serves primarily as the connection to the liquid
cathode, providing an external termination.
In actual practice, porous paper is wrapped around the anode
and saturated with the electrolyte to eliminate the spillage problem.
There are two common types of electrolytic capacitors: a) Aluminum b) Tantalum
Both
employ the same basic principle. The aluminum or Tantalum anode is covered with
an oxide film. A suitable liquid or solid electrolyte is the cathode. The
Aluminum type is by far the most popular because of its lower cost. The
aluminum –oxide film has a very high resistance to current in one direction and
has very low resistance to current in opposite direction. In other words, film
acts as a dielectric in first instance and as a plate in second case. Because
of this electrolytic are polarized. If the designated polarity is not observed,
the oxide film on anode will breakdown and migrate to cathode connection,
resulting in prompt failure of capacitor.
Electrolytics
are described as belonging to one of the three basic families;
Polarized
type
This
type has one anode, the liquid cathode and a cathode connection. Polarity must
be observed.
Semi
polarized type
In
many energy storage applications a certain amount of current reversal is often
encountered. In such cases this type is recommended. In this type, the primary
anode has a relatively thick oxide surface. The cathode connection now becomes
the secondary anode with a thin oxide surface. Also liquid cathode has a
slightly different chemical composition.
Non-polarized
This
type is used in audio cross over networks and ac motor starting applications.
Here there is a complete reversal of polarity; therefore, two anodes are
required. The cathode connection now becomes a second, and equal, anode.
Obviously size will be affected. Infact, the third type called nonpolarized is just
twice as large as a polarized type of equivalent capacitance and voltage
rating.
MICA CAPACITORS
Mica is popularly known as Isin glass. Important
characteristics of Mica:
i) Its ability to operate at very high temperature (upto 500
oC).
ii) The material is almost totally inert and will not change
with age, either chemically or physically.
iii) Mica is usable as a dielectric in its naturally state.
iv) It can be readily split into very thin sheets.
Mica capacitors are made by a method of depositing a thin
layer of silver on each side of sheet of Mica was developed. This is done by a
type of silver screen process. The silver is then fired in a furnace.
The principal advantage of Mica capacitor is its excellent
degree of stability over a wide range of operating temperatures.
Mica capacitors are also among the best types to use where
radio frequencies are involved.
Disadvantages of Mica capacitors:
i) They are relatively bulky when compared to other
capacitors on a pure capacitance vs volume basis.
ii) The flat plates and method of construction lead to
resonant frequency problems in some circuits.
What is a relay?
A relay is an electromagnetic switch. An actuating current passed in a coil operates one or more galvanically separated contacts. In fact it is a remote controlled switch capable of switching multiple circuits, either individually, simultaneously or in sequence.
The most widely used type of relay is electromechanical relay. In electromechanical relays the switching element is a mecahncial contact, actuated by an electromagnet. This is the msot widely used type of relay design. The principal internal functions of the electromechanical relay are:
The most widely used type of relay is electromechanical relay. In electromechanical relays the switching element is a mecahncial contact, actuated by an electromagnet. This is the msot widely used type of relay design. The principal internal functions of the electromechanical relay are:
- Conversion of electrical current into magnetic field
- Conversion of magnetic field into a mechanical force
- This Mechanical force operates the contacts
- Contacts switch and conduct electrical current
Typical applications of relays are as follows:
- Laboratory instruments
- Telecommunication systems
- Domestic appliances
- Traffic control
- Control of motors & solenoids
- Air conditioning & heating
Natural Radioactivity in Soil (Bq.Kg-1)
Country
|
Type
of Radioactive Isotope
|
|||
K-40
|
U-238
|
Ra-226
|
Th-232
|
|
India
|
400
|
29
|
29
|
64
|
China
|
440
|
33
|
32
|
41
|
Japan
|
310
|
29
|
33
|
28
|
USA
|
370
|
35
|
40
|
35
|
Russia
|
520
|
19
|
27
|
30
|
Spain
|
470
|
NA
|
32
|
33
|
Mean values are given from wide range of values
Courtesy: UNSCEAR, 2000Natural Background Radiation in Various Cities of India
|
City
|
µGy.yr-1
|
||
|
Cosmic
|
Terrestial
|
Total
|
|
|
Mumbai
|
280
|
204
|
484
|
|
Kolkata
|
280
|
530
|
810
|
|
Delhi
|
310
|
390
|
700
|
|
Chennai
|
280
|
510
|
790
|
|
Bangalore
|
440
|
385
|
825
|
As one shifts from Mumbai to Delhi, he is going to get 216 µGy
additional natural radiation dose which is 10 times more than that from a
nuclear power plant.
WE LIVE IN NATURALLY RADIOACTIVE WORLD
We are exposed
to radiation from the sun and outer space, also from the naturally occurring
radioactive materials present in the earth, the house we live in, the buildings
where we work, the food and drink we consume.
Where we live in
The
houses are made up of materials which contain radioactivity. Gamma radiation
from walls, floor & ceiling, and Radon and Thoron progeny are major sources
of radiation exposure. Especially in closed rooms, Radon is the significant
dose contributing factor.
Natural Radioactivity (Bq.Kg-1) in Building Materials used
in India
|
Material
|
Type
of Radioactive isotope
|
||
|
K-40
|
Ra-226
|
Th-232
|
|
|
Cement
|
5-385
|
16-377
|
8-78
|
|
Brick
|
130-1390
|
21-48
|
26-126
|
|
Stone
|
48-1479
|
6-155
|
5-412
|
|
Sand
|
5-1074
|
1-5047
|
4-2971
|
|
Granite
|
76-1380
|
4-98
|
103-240
|
|
Clay
|
6-477
|
7-1621
|
4-311
|
|
Fly
Ash
|
6-522
|
7-670
|
30-159
|
|
Lime
stone
|
6-518
|
1-26
|
1-33
|
|
Gypsum
|
70-807
|
7-807
|
1-152
|
We are always in natural background radiation*
Cosmic-from the sun and outer space – 0.4mSv.Yr-1
Terrestrial – from the earth’s crust – 0.5mSv.yr-1
Radon – from decay of Uranium/radium – 1.2mSv.yr-1
Internal sources in the body(eg: 40K)
--- 0.3mSv.yr-1
Total Dose from
Natural Sources: ----2.4 mSv.Yr-1
What we drink
Radioactivity in
milk is over 200 times more than in
drinking water and 3 times that in beer.
From a cup of milk ,
180 beta particles of Ptassium-40 are emitted per minute
From a cup of tea, 91
beta particles of Potassium-40 are emittd per minute from tea leaves(excluding
milk and water)
What we eat
|
Food
stuff
|
K-40
(Bq.Kg-1)
|
|
Rice
|
40-90
|
|
Leafy vegetables
|
80-220
|
|
Brinjal
|
90-140
|
|
Carrot
|
60-120
|
|
Beetroot
|
90-120
|
Radiation Doses from Cosmic Rays
|
Distance
above Ground
|
Dose
Rate in µSv. h-1
|
|
~ 15 Km above ground
|
10
|
|
~ 10 Km above ground
|
5
|
|
~ 8 Km above ground
|
2
|
|
~ 2 Km above ground
|
0.1
|
|
Sea Level
|
0.03
|
Courtesy: Radiation Safety, IAEA (1996), NRPB, UK
Comparison Between Wastes From A Nuclear Reactor & Coal Based Thermal Power Plant [1000 Mwe Each]
|
Thermal
Power Plant
|
|
Nuclear
Power Plant
|
||
|
Ash:
|
320,000
tonnes
|
|
High
Level:
|
27
tonnes spent fuel or 3 Cu.m after reprocessing
|
|
CO2:
|
6.5
Million tonnes
|
|
||
|
SO2:
|
44,000
tonnes
|
|
Intermediate
level:
|
310
tonnes
|
|
NO2:
|
22,000
tonnes
|
|
Low
Level:
|
460
tonnes
|
Units of Radioactivity
------------------------------------------------------------------------------------------------------------
Physical Quantity SI Unit Non-SI Unit
------------------------------------------------------------------------------------------------------------
Activity Becquerel Curie (Ci)
Absorbed Dose Gray RAD
Dose Equivalent Sievert REM
Exposure Coulomb/Kg Roentgen
------------------------------------------------------------------------------------------------------------
Physical Quantity SI Unit Non-SI Unit
------------------------------------------------------------------------------------------------------------
Activity Becquerel Curie (Ci)
Absorbed Dose Gray RAD
Dose Equivalent Sievert REM
Exposure Coulomb/Kg Roentgen
------------------------------------------------------------------------------------------------------------
BF3 Properties
- Molecular Weight : 67.82
- Density of gas : 3.06 gm / litre at 0 deg C, 760mm of Hg
- Density of Liquid : 1.68 gm/cc @ -128 deg C
- Density of solid : 1.87 gm/cc
- Melting Point : -128 deg C
- Boiling Point : -100 deg C
- Triple Point : - 123 deg C
The Cost of Oxygen!!
The cost of Oxygen. Very interesting!!!
In one day a human being breathes oxygen equivalent to three cylinders.
Each oxygen cylinder on an average costs Rs 700, without subsidy.
So in a day one uses Oxygen worth Rs 2100 and for a full year it is Rs 7,66,500.
If we consider an average life span of 65 years; the costs of oxygen we use become a staggering sum of Rs 500,00,000. Rs 50 million.
All this oxygen is derived free of cost from the surrounding trees..
Very few people look at trees as a resource and there is rampart tree cutting going on everywhere which should stop.
Please pass this to your friends and care for trees.
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