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Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

An earthquake generates both transverse $(S)$ and longitudinal $(P)$ sound waves in the earth. The speed of $S$ waves is about $4 \,\,km \,\,s^{-1}$ and that of $P$ waves is about $8 \,\,km \,\,s^{-1}$. A seismograph records $P$ and $S$ waves from an earthquake.The first $P$ wave arrives $4$ min before the first $S$ wave. The epicentre of the earthquake is located at a distance of about

  1. $192 km$
  2. $384 km$
  3. $1920 km$
  4. $3840 km$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Let $\nu _1, \nu _2$ be speed $S$ of $S$ and $P$ waves and $t _1,t _2$ be the time taken by these waves to travel to reach the seismograph. Let the epicenter of the earthquake is located at a distance $d$ from the seismograph. Then,
$d = V _1 t _1 = V _2 t _2$          ................ .....(i)
Here, $V _1 = 4 km \,\,s^{-1}$ and $V _2 = 8 km \,\,s^{-1}$
$\therefore 4t _1 = 8t _2 \Longrightarrow t _1 = 2t _2$           ....(ii)
and  $t _1 - t _2 = 4 min = 240 s$
$\therefore 2t _2 - t _2 = 240$      ....................  [using (ii)]
or $t _2 = 240 s$
put in Eq. (ii), we get,
$t _1 = 2 \times 240 s = 480 s$
From Eq. (i), we get, $d = (4 km \,\,s^{-1}) (480 s) = 1920 km$
Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

The weak zone around the boundaries of plates underneath the Earth, which is prone to slide and cause an earthquake is commonly known as :

  1. Fault zone

  2. Eruption zone

  3. Explosive zone

  4. Sliding zone
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The weak zone around the boundaries of plates underneath the Earth, which  is prone to slide and cause an earthquake is known as Seismic or Fault Zones.

The correct option is A.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

The natural calamity that cannot be predicted accurately in advance:

  1. Flood

  2. Cyclone

  3. Earthquake

  4. Famine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

While floods, cyclones, and famines often have precursors or meteorological indicators that allow for some level of prediction, earthquakes currently cannot be predicted with accuracy regarding time, location, or magnitude.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

Waves produced during in earthquake are _____waves. .

  1. ultrasonic

  2. infrasonic

  3. audible

  4. both (1) and (2)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Earthquakes produce seismic waves that travel through the earth. These waves, particularly the primary waves, often have frequencies below the human audible range, classifying them as infrasonic.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

The point where the waves originate is called the _______ of the earthquake

  1. centre

  2. epicenter

  3. focus

  4. origin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is C.

The point where the waves originate is called the focus of the earthquake.
The point within the earth along the rupturing geological fault where an earthquake originates is called the focus, or hypocenter. The point on the earth's surface directly above the focus is called the epicenter. Earthquake waves begin to radiate out from the focus and subsequently form along the fault rupture. If the focus is near the surface between 0 and 70 km (0 and 40 mi) deepshallow-focus earthquakes are produced. If it is intermediate or deep below the crust between 70 and 700 km (40 and 400 mi) deepa deep-focus earthquake will be produced. Shallow-focus earthquakes tend to be larger, and therefore more damaging, earthquakes. This is because they are closer to the surface where the rocks are stronger and build up more strain.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

In which of the following states of India, earthquake is most likely to occur?

  1. Gujarat

  2. Chhattisgarh

  3. Tamil Nadu

  4. Kerala
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In India, the seismic or fault zores lie below Kashmir, Western and Central Himalays, North-East, Runn of Kutch and Indo-gangetic plane. So, among the options provided, earthquake is most likely to occur in Gujarat.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

An earthquake is caused by

  1. shaking of the earth

  2. strain building up in the tectonic plates

  3. plates slipping along the fault lines

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An earthquake is caused by shaking of the earth, strain building up in the tectonic plates, plates slipping along the fault lines, etc.
Earthquake is shaking of the earth's surface caused by rapid movement of the earth's rocky outer layer. Earthquakes occur when energy stored within the earth, usually in the form of strain in rocks, suddenly releases. This energy is transmitted to the surface of the earth by earthquake waves.

Multiple choice physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

Match the following and choose the correct answer.

Table A Table B
a. Earthquake        1. Prevent leakage
b. Lightning 2. Fault zone
c. Insulation 3. Detection of charges
d. Electroscope 4. Earthing

  1. a-2, b-4, c-1, d-3

  2. a-3, b-4, c-2, d-1

  3. a-4, b-3, c-2, d-1

  4. a-1, b-2, c-3, d-4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fault zones are highly prone to earthquakes.

Earthing is done to save buildings from lightning.
Insulation is done on conducting wires to prevent charge leakage.
Electroscopes are used to detect the presence of charges in a body.