PHYSICS COMPETITION for 3rd GRADES

When a magnet bar is divided into small pieces:

• We get small non magnetized pieces.

• Each piece will have only one magnetic pole either north or south

• Each piece will have four magnetic poles, two north poles and two south poles.

• Each piece will have two magnetic poles, one north and one south.

Fill in the blank with appropriate word.

Similar poles......................and different poles attract.

Fill in the blank with appropriate word.

An ................................. is an electrical apparatus used in electric experiments.

Materials are classified in respect to their abilities to electrically conduct:

• Diamagnetic, Paramagnetic, and Ferromagnetic

• Insulator and Conductor

• Rubbing, Conduction, and Induction

• Ferromagnetic

Answer the blank with correct option.

The ............................ in any region is the space which surrounds the magnet in which the effect

of the magnet would be observed.

• Magnetic Poles

• Magnetic field lines

• Magnetic Field

• Magnetic Force

Magnetic field is represented by lines that characterized by being:

• Invisible

• Cross between them

• closed

• Moving from the north pole to the south pole outside the magnet

Which one of the followings defines negatively charged atom?

• If the number of electrons of an atom decreases

  as a result of releasing some of them to the outside of the body,

  then the atom transfers to a positive ion. This will result in the

  body becoming ..................... charged (+q).

• Those bodies which gain electrons from some other bodies

  their atoms convert to negative ions, then the body will be ........................... charged (-q).

• The electrical material attracts small particles such as (small pieces of paper, pieces of hay) when it is rubbed down with a piece of woolen cloth.

When losing a charge (1.6x10^-9 C) from a conducted body which is isolated and neutrally charged, then the number of electrons that was lost from this body will equal:

• 10¹⁰ electrons

• 10⁹ electrons

• 10⁸ electrons

• 10¹² electrons

Which of the followings are correct?

• The Poles of a Magnet are the areas at which the magnetic forces are weakest.

• Similar magnetic poles repel and different magnetic poles attract.

• The charge of proton inside the nucleus of an atom is negative.

• The magnetic field is represented in drawing by lines and these are close lines (invisible) heading from the North pole to South one and completing its circuit inside the bar.

When a positively charged body gets closer to the electroscope disk with two positively charged leaves, this will lead to:

• The leaves will get closer

• The leaves will get identified (close gap)

• Nothing changes

• The leaves will get apart further