Tag: lightning safety

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Multiple choice physics some natural phenomena lightning conductors lightning safety advanced of lightning

                      is engineered to protect an elevated structure in the event of lightning strike.

  1. A lightning conductor

  2. Copper wire

  3. A lightening shield

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A lightening conductor is a metal rod mounted on a structure and designed to protect the structure from lightening strike. 

Multiple choice physics some natural phenomena lightning conductors lightning safety advanced of lightning

If the instantaneous current in a metallic wire is $i = \left( {5 + 10t} \right)A$ then find amount of charge flown through it from $t = 2s$ to $t = 3s$ is

  1. 10 C

  2. 20 C

  3. 30 C

  4. 40 C
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given instantaneous current,

$i=(5+10t)A$
and from the definition of instantaneous current,  $i=\dfrac { dq }{ dt } $
$\Rightarrow \quad \left( 5+10t \right) =\dfrac { dq }{ dt } $
$dq=\left( 5+10t \right) dt$
Integrating implies,
$Q=5t+{ 5t }^{ 2 }$
At $t=2$,
                ${ Q } _{ 1 }=30C$
At $t=3$,
                ${ Q } _{ 2 }=60C$

$\therefore $  Option (C) is the correct option.

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

Assertion : An earthquake will not cause uniform damage to all building in an affected area, even if they are built with the same strength and materials.
Reason : The one with its natural frequency close to the frequency of seismic wave is likely to be damaged less.

  1. If both assertion and reason are true and reason is the correct explanation of assertion.

  2. If both assertion and reason are true and reason is not the correct explanation of assertion.

  3. If assertion is true but reason is false.

  4. If both assertion and reason are false.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An earth quake will not cause uniform damage to all building in an affected area because the natural frequencies of a building depend on its height and other size parameters and the nature of building materials.
The one with its natural frequency close to the frequency of seismic wave is likely to be damaged more.

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.