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Seismograph
Seismograph | ||||||
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A seismograph is a sensitive device for recording and measuring the vibration below the earth’s surface. It is especially used for detecting earthquakes and underground nuclear explosions. Wouldn’t you like to make one at home?
If you can’t find a wooden support with a crossbar, make one for yourself. Take a wooden plank and fix a wooden scale upright on it. Fix another wooden scale to this one horizontally. Ensure that the second wooden scale is parallel to the wooden plank. Place the wooden structure on a table. Hand the spring from
a crossbar (see picture). Make a ball of damp clay or play dough and fix it to
the other end of the spring. Stick a ballpoint pen into the clay ball (see
picture). Ensure that the pen is
Stand the white cardboard in front of the wooden crossbar in such a manner that the pen touches the cardboard. Your seismograph is all set now. Now you need an earthquake to record the tremor! Hit the table hard with your fist or a blunt object. The vibrations produced will result in the pen making a wave pattern on the cardboard. You can hit the table with varying intensities and note down the wave pattern marked on the cardboard. You may later plot the data on a graph and interpret it.
Source: The Hindu (Indian Newspaper) More information on Seismograph: U.S. Geological Survey |
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Web Design
by member
Aswin Rangaswamy, P.E |
You
need: metal spring, pen, clay or play dough, wooden support with a
crossbar, table, and white cardboard.
parallel
to the base of the wooden structure and the table. 
The
seismograph used by meteorologists’ works in a slightly more complicated manner,
using the same principle as above. The seismograph records the movements in the
earth with a device called the Richter scale. The scale is marked from 1 to 9
and indicates the strength of the earthquake. An earthquake measuring five or
less is considered minor. An earthquake measuring seven on the Richter scale is
serious and could cause severe damage to lives and property. It is twenty times
stronger than the earthquake measuring five.