It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it.
Pencil sharpener gets attracted by both the poles of magnet when it is placed near it because the blade of the sharpener is made up of iron which is a metal. As we know metal is attracted towards the magnet easily.
You are given an iron strip. How will you make it into a magnet?
How is a compass used to find directions?
Where are poles of a bar magnet located?
A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?
A magnet was brought from different directions towards a toy boat that has been floating in water in a tub. Affect observed in each case is stated in Column I. Possible reasons for the observed affects are mentioned in Column II. Match the statements given in Column I with those in Column II.
Column I Column II
Boat gets attracted towards the magnet Boat is fitted with a magnet with north pole towards its head
Boat is not affected by the magnet Boat is fitted with a magnet with south pole towards its head
Boat moves towards the magnet if north Boat has a small magnet fixed along its length
pole of the magnet is brought near its
head
Boat moves away from the magnet Boat is made of magnetic material when north pole is brought near its head
Boat floats without changing its direction Boat is made up non-magnetic material
Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting action between them for each situation. Fill in the blanks.
Column I Column II
N - N _________
N - _________ Attraction
S - N _________
_________ - S Repulstion
Write any two properties of a magnet.
State whether the following statements are true or false
(i) A cylindrical magnet has only one pole.
(ii) Artificial magnets were discovered in Greece.
(iii) Similar poles of a magnet repel each other.
(iv) Maximum iron filings stick in the middle of a bar magnet when it is brought near them.
(v) Bar magnets always point towards North-South direction.
(vi) A compass can be used to find East-West direction at any place.
(vii) Rubber is a magnetic material.
Fill in the blanks in the following
(i) Artificial magnets are made in different shapes such as __________, __________ and ____________.
(ii) The Materials which are attracted towards a magnet are called________.
(iii) Paper is not a ______ material.
(iv) In olden days, sailors used to find direction by suspending a piece of ___________.
(v) A magnet always has __________ poles.
(a) Which kind of garbage is not converted into compost by the redworms?
(b) Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Do you find that all living beings need the same kind of food?
Name the major nutrients in our food.
Classify the following fibres as natural or synthetic:
nylon, wool, cotton, silk, polyester, jute
Name five objects which can be made from wood.
Why do we need to separate different components of a mixture? Give two examples.
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal.
Fill in the blanks:
(a) Joints of the bones help in the ——————— of the body.
(b) A combination of bones and cartilages forms the _______ of the body.
(c) The bones at the elbow are joined by a ______________________ joint.
(d) The contraction of the _____________ pulls the bones during movement.
Match the items in Column I with one or more items of Column II.
Column I Column II
Upper jaw have fins on the body
Fish has an outer skeleton
Ribs can fly in the air
Snail is an immovable joint
Cockroach protect the heart
shows very slow movement
have a streamlined body
The height of a person is 1.65 m. Express it into cm and mm.
Would the bulb glow after completing the circuit shown in Fig. 12.14 if instead of safety pin we use an eraser?
How do plants and animals help each other in the exchange of gases in the atmosphere?
Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
S.No. | Change | Can be reversed (Yes/ No) |
---|---|---|
1 | The sawing of a piece of wood | |
2 | The melting of ice candy | |
3 | Dissolving sugar in water | |
4 | The cooking of food | |
5 | The ripening of a mango | |
6 | Souring of milk |
State whether the following statements are true or false:
a) Yarn is made from fibres.
b) Spinning is a process of making fibres.
c) Jute is the outer covering of coconut.
d) The process of removing seed from cotton is called ginning.
e) Weaving of yarn makes a piece of fabric.
f) Silk fibre is obtained from the stem of a plant.
g) Polyester is a natural fibre.
Do you find that all living beings need the same kind of food?
Fill in the blanks:
a) Plant fibres are obtained from_________ and ________ .
b) Animals fibres are __________ and ___________ .
What is winnowing? Where is it used?
In which part of a flower, you are likely to find the ovary?