Question

Which of the following statements is false?
A. The P-wave shadow zone is larger than the S-wave shadow zone.
B. P waves travel mostly in the outer core than in the lower mantle.
C. Liquids do not transmit S waves.
D. Seismic waves follow curved paths through the interior of the earth.

Answer 1

Hint: P-waves and S-waves have different properties and therefore travel differently. Not all kinds of seismic waves can travel through all the layers of the Earth. So not every kind of wave will reach the surface. The path which the waves follow depends on the surroundings. It always takes the path where there is least resistance.

Complete Answer:
Seismic waves are waves of energy which move through the layers of the Earth's interior and the surface. Seismic waves are broadly classified into two types- the surface waves and the body waves. The body waves travel through the different layers of the Earth and the surface waves travel at the Earth's surface. The body waves are divided into P-waves (primary waves) and S-waves (secondary waves). All these different types of waves have their own unique features. Let us now check the veracity of each of the given statements.

A. It is incorrect that the P-wave shadow zone is larger than the S-wave shadow zone. P-wave shadow zones are formed due to refraction, which causes the waves to deviate away. But S-wave shadow zones are created because these waves are completely blocked. Thus the S-wave shadow zones are much larger.

B. It is true that P waves travel mostly in the outer core than in the lower mantle. P-waves in the mantle get refracted away and reach the surface more quickly.

C. It is also true that Liquids do not transmit S-waves. This is the reason why S-waves are not transmitted through the outer core since it is liquid.

D. It is true that seismic waves follow curved paths through the interior of the earth. This is because the path changes due to variation in composition, temperature and pressure in the layers of the Earth

Therefore, the correct answer is Option A.

Note: P-waves are also known as compression or longitudinal waves. S-waves are also known as shear or transverse waves. Seismic wave shadow zones were first discovered in around 1910.