Q. & A.s ‑‑‑ SCIENCE & TECHNOLOGY -- 2
1.
What is blue moon?
If there come
two “full moon ” s in a month the first
one is called fullmoon day and the other is called “blue Moon”.
2. Which isotope isotope
can trace out the source of water?
Krypton 81.
3. What are mach numbers.
a.
Speed at sound speed is
called mach 1.
b.
Speeds below sound are
called sub-sonic = < mach 1
c.
Speeds above mach 1 are
called super-sonic.
d.
Speeds above mach 5 are
called hyper sonic.
e.
Concorde travels at
mach 2
4. How does the Sun give
this much of energy?
a.
In every second crores
of nuclear fusion reactions are going on.
b.
Mass consumed = 4.26 x 109 kgs per
sec.
c.
Energy released = 384.6 x 1026 watts
per sec.
d.
Earth receives = 94 x 1012 mega
watts
e.
Per sec 100 x 10 9 kgs hydrogen is converted into 695 x 10 9
kgs of He.
f.
Temperature at the core = 1.5 crore o K
5. When will sun die?
When the
entire Hydrogen gas is converted into Helium then there won’t be further fuel
to burn. That is the death of SUN.
6.
Write the data of the Sun.
a.
Distance from earth 15
crore kilometers
b.
Light takes 8
minutes, 19 seconds
c.
From the centre of the
galaxy 26,000 light years
d.
Sun goes round the
galaxy at 220
kilometers per second
e.
Diameter 1.4
X 106 kms
f.
Circumference 109 X
Earth 4.4
X 106 kms
g.
Volume 13 lakhs x Earth 1.4 x 1018 cu. kms
h.
Mass 3,33,000 x Earth 1.4 x 1030 kgs
i.
G 28g 27.94
g = 27.94 x 9.8 m/sec2
j.
Velocity – rotation 7200
kmph
k.
Type of star G
type
l.
State of matter plasma
m.
Escape velocity 617.7
kmps
n.
Temperature – core 1.5
x 107 o K
o.
Temperature – outer 5778
o K
p.
Luminosity 3.8
x 10 26 Watts
q.
Age 4.57
x 10 9 years
7. What are the things
emitted by Sun.
The sun emits
gamma rays, neutrinos, protons, light, heat, gravitational waves, radioactive
rays, solar wind, sun spot activity etc.
8.
Why it is cold at high altitudes?
As we go up in troposphere,
for every 1 km height 6.4oC temperature is reduced. That is why when
we go up and up the temperature is decreased. That is why there is ice on Himalayas.
9.
Why do water drops dance when poured on a hot plate?
When we pour water on hot
plate the lower layer of water drop gets evaporated. The next layer touches the
hot plate. This sequence is done very fast. That why we feel that the water
drop dances.
10.
Can woolen dress give us heat?
No. woolen is a bad conductor
of heat. It does not allow heat from our body to go out and does not allow cool
air from touching our body. That is why we feel hot.
11.
What are different years?
Lunar year 954 days
Leap year 366 days
Julius year 3561/2
days
Solar year 365 days 5
hrs 48 m 9 sec
Sybil year 368 d 6 h 9 m 9
s
Anomalistic year 365 d 6
h 13 m 19.3 s
Gregorian year 967 d 5
h 49 m 12 s
12.
What is the Indian system of measuring place values.
1.
Units,
2.
Tens,
3.
Hundreds,
4.
Thousands,
5.
Ten-thousands,
6.
Lakhs,
7.
Ten-lakhs,
8.
Crores,
9.
Ten-crores,
10.
Arabs,
11.
Ten-arabs,
12.
Kharabs,
13.
Ten-kharabs,
14.
Nils
15.
Ten-nils
16.
Padams
17.
Ten-padams
18.
Sankhs
19.
Ten-sankhs.
13.
How is angle measured ?
60’’ = 1 minute
60’ = 1 degree
90 degrees = 1 right angle
180 degrees = 1 straight line
360 degrees = 1 circle
14.
How is frequency measured?
1 cycle/sec = 1 Hz. = 1
1000 Hz = 1
kilo Hz = 103 Hz
1000 K Hz = 1
Mega Hz = 106 Hz
1000 M Hz = 1
Giga Hz = 109 Hz
1000 G Hz = 1
Tera Hz = 1012 Hz
1000 T Hz = 1
Peta Hz = 1015 Hz
15.
How is place value measured in western system?
Units
Tens
Hundreds
Thousands =
103
Ten thousands = 104
Hundred thousands = 105
Million = 106
Billion =
109
Trillion = 1012
Quadrillion =
1015
Quintillion
Sextillion
Heptillion ………
16. The powder of any glass is white. Why?
Each tiny piece of the glass powder has
many faces. The light falling on those tiny faces is reflected. There is no
refraction. That is why the powder of any coloured glass is white.
17. What is a light year?
The distance travelled by light in one
year is called one light year.
18. What is periscope?
It is a Z shaped device. It is used by
soldiers sitting in trenches, captains to see from underwater submarine…
without being detected.
It is because of diffraction of light
which can be explained by wave theory of light
.
19. If sun light is outside how is that inside the
house there is light?
Light
has a property called diffraction. That means it bends and travels. The light
falling on roof tops bends and travels inside the house making it bright.
20. What is the velocity of light?
3,00,000 kilometres per second.
21. Why signals are red or green in colour?
These are the colours that can be seen
to far distances.
22. Why leaves are green in colour?
It is because of the presence of chlorophyll.
23. What are the fundamental colours?
Red, blue, green are called the
fundamental colours.
24. How many colours can our eye distinguish?
Our eye can distinguish 17,000 colours.
25. What are the properties of light?
Light has
1. Reflection
2. Refraction
3. Interference
4. Diffraction
5. Polarization
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