FUNDAMENTAL UNITS
(i) Metre (m) : 1 metre is equal to the
length of the path travelled by light in
vacuum in 1/2 99792458 of a second where
speed of light is 299792458 m/s. Recently,
the definition of 1 metre of length is realized
by using the iodine stabilized helium neon
lasers.
(ii) Kilogram (kg) : A standard block of
Platinum Iridium alloy preserved in the
International Bureau of Weights & Measures
at Sevres, near Paris, France is used as a
prototype of unit of mass and one kilogram
is equal to the mass of this alloy.
(iii) Second (s) : The definition of second
is based on an atomic clock which works
on energy radiation from an isotope of
caesium (Cs-133). One second is equal to
the duration of 9, 192, 631, 770 periods of radiation corresponding to unperturbed
transition between the two specific energy
levels of the ground gaseous state of Cs-
133 isotope. The caesium atoms in the
atomic clock act like a pendulum in a
pendulum clock. The atomic clock gives
the most accurate time with an error of 1
second only in 5000 years.
Contents in the pdf
Units & Measurement
2. Motion
3. Work, Energy and Power
4. Gravitation
5. Properties of Matter
6. Space Exploration
7. Simple Harmonic Motion
8. Sound
9.optics
10. Heat
11. Electromagnetic Radiation
12. Atomic Physics
13. Astronomy
14. Communication System
15. Electromagnetism
16. Physics at a Glance-I
Full full pdf click the download button below
إرسال تعليق