The three major scales used to measure earthquakes are mercalli scale, richter scale and magnitude scale. t or f

There are various scales for the measurement of earthquakes.

As per the question the first one is the Mercalli scale.It is a seismic intensity scale which is used to measure the intensity of earthquake.Here the intensity refers to the effect of earthquake on a particular zone.

The Ritcher scale is also associated with the measurement of earth quake.It is the seismic scale which is used to get the quantitative measurement of approximate size of earthquake .Here the size of the earthquake is obtained by taking the logarithm of amplitude waves obtained during earthquake .The data is provided by the seismograph.

The third one is the magnitude scale.It is also one type of seismic scale which is also similar to The Ritcher scale .It measures the size of earthquake.

Hence all the three scales are related to earthquake.Hence the statement is true.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

trig 15.3 cos