Tag: physics

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Multiple choice physics air, winds and cyclones the concept of bernoulli's principle air exerts pressure wind and pressure wind and rain uneven heating of earth

The continuous spectrum is obtained when the incandescent substance is?

  1. In state of atomic vapour

  2. In solid state

  3. In state of molecular vapour

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An incandescent light bulb produces a continuous spectrum because the source of the light is a metal filament (i.e. solid).

Multiple choice physics properties of a magnetic field earth - a gigantic magnet magnetic field of earth introduction to magnetic field and magnetic flux

The magnetic south pole of the earth is situated near the 

  1. geographic south pole

  2. geographic north pole

  3. geographic east

  4. geographic west
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

'Magnetic North' is a LOCATION, so-named to distinguish it from True North -it has NOTHING to do with its magnetic POLARITY. The magnetic polarity at this location is south -which is why it attracts the north-seeking pole of a compass needle or magnet.

Multiple choice physics properties of a magnetic field earth - a gigantic magnet magnetic field of earth introduction to magnetic field and magnetic flux

The shape of the earth's magnetic field resembles that of an imaginary

  1. current-carrying circular loop

  2. solenoid

  3. U-shaped magnet

  4. bar magnet
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Answer is D.

A freely suspended magnet always points in the North-South direction even in the absence of any other magnet. This suggests that the Earth itself behaves as a magnet which causes a freely suspended magnet (or magnetic needle) to point always in a particular direction: North and South. The shape of the Earth's magnetic field resembles that of a bar magnet of length one-fifth of the Earth's diameter buried at its center.
The South Pole of the Earth's magnet is in the geographical North because it attracts the North Pole of the suspended magnet and vice versa. Thus, there is a magnetic S-pole near the geographical North, and a magnetic N-pole near the geographical South. The positions of the Earth's magnetic poles are not well defined on the globe; they are spread over an area. The axis of Earth's magnet and the geographical axis do no coincide. The axis of the Earth's magnetic field is inclined at an angle of about 15 degrees with the geographical axis. Due to this a freely suspended magnet makes an angle of about 15 degrees with the geographical axis and points only approximately in the North-South directions at a place.

Multiple choice physics properties of a magnetic field earth - a gigantic magnet magnetic field of earth introduction to magnetic field and magnetic flux

The angle of declination at a place is the angle

  1. Between the vertical plane and the geographical meridian

  2. Between the vertical plane and the magnetic meridian

  3. Between the geographical meridian and magnetic meridian

  4. Between the geographical meridian and horizontal plane
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A freely suspended magnet always points in the North-South direction even in the absence of any other magnet. This suggests that the Earth itself behaves as a magnet which causes a freely suspended magnet (or magnetic needle) to point always in a particular direction: North and South.

The vertical plane passing through the axis of a freely suspended magnet is called magnetic meridian. The direction of Earth's magnetic field lies in the magnetic meridian and may not be horizontal. The vertical plane passing through the true geographical North and South (or geographical axis of Earth) is called geographical meridian. The angle between the magnetic meridian and the geographic meridian at a place is called declination at that place.

Multiple choice physics properties of a magnetic field earth - a gigantic magnet magnetic field of earth introduction to magnetic field and magnetic flux

It is a common notion that the earth's magnetism is due to the

  1. presence of a huge permanent magnet in the interior of the earth

  2. presence of electric currents circulating in the interior of the earth

  3. influence of the sun's magnetic field

  4. influence of a nuclear explosion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the Earth, the liquid metal that makes up the outer core passes through a magnetic field which causes an electric current to flow within the liquid metal. The electric current, in turn, creates its own  magnetic field—one that is stronger than the field that created it in the first place.

Multiple choice physics properties of a magnetic field earth - a gigantic magnet magnetic field of earth introduction to magnetic field and magnetic flux

Even though earth is a giant magnet, all the iron does not stick to it at north and south pole because

  1. Iron is embedded in between rocks

  2. Very less iron is present near the magnetic poles of earth

  3. Force of earth's magnetism is weak

  4. Much iron is scattered away from the poles
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The Earth has a magnetic field which is produced deep in the interior by electrical currents in the molten part of the core.At the surface of the Earth and beyond the magnetic field is weak.It is just strong enough to rotate a small magnet, called a compass needle, balanced with little friction on a pointed support.
The Earth itself is not a magnet.The magnetic field produced in the core is much more complex in form that what would be expected for a simple magnet such as a bar magnet.The illustration of the Earth as if there is a bar magnet inside are misleading.