Group (Physics)
Some of the processes to demagnetize a magnet are:
a) By dropping or striking a magnet.
b) By heating the magnets.
c) By rubbing similar poles of the magnet.
| Fundamental units | Derived units | |
|---|---|---|
| Definition | Fundamental units are the units of measurement which are independent of each other or any other units. | Derived units are the units of measurement which are dependent on each other and other units for their existence. |
| Derivation | Fundamental units cannot be derived from any other units. | Derived units can be derived from other basic units. |
Some of the evidences to support terrestrial magnetism are:
a) A freely suspended bar magnet always shows the geographical N-S direction due to terrestrial magnetism.
b) The ores of iron or any other buried magnet show magnetic property.
c) The angle of inclination and angle of declination are shown by a magnetic needle.
d) In the magnetic field of a magnet, the neutral point can be formed.
A dry cell is a portable cell. A dry cell consists of a zinc container whose base acts as the negative electrode. The carbon rod placed at the centre with a brass cap (metal cap) acts as the positive electrode. This is surrounded by a mixture of manganese dioxide and charcoal in a muslin bag. The electrolyte uses is a moist paste of ammonium chloride. The outer body (excluding the base) of the zinc container is insulated with cardboard.
When the dry cell is connected in a circuit comprising a bulb, current flows in the circuit due to the chemical reaction that takes place in the cell. This makes the bulb glow. The dry cell is a primary cell and it cannot be recharged.
Here, we have to calculate the area and volume of a book.
For that, let us collect the given information.
The information given are;
The length of a book (let us represent it by l) is equal to 18 centimetres.
Length (l) = 18 cm
The breadth of the book (let us represent it by b) is equal to 8 centimetres.
Breadth(b) = 8 cm
The height of the book (let us represent it by h) is equal to 5 centimetres.
Height (h) = 5 cm
Now, we have to calculate the area of the book (let us represent it by A)
Area (A) =?
And we have to calculate the volume of the book (let us represent it by V).
Volume (V) =?
We know,
Area of book (A) is the product of its length (l) and breadth (b).
A = l × b
Substituting the given values in the formula
A = l × b
We get,
A is equal to
Let us write 18 in the place of ‘l’ and 8 in the place of ‘b’.
Remember that it is not necessary to write the units while performing the calculations.
A = 18× 8
Multiplying 18 and 8 together, we get 144.
A = 144
Remember that we should not forget to write the unit while writing the final answer.
So, let us write the unit of area (square centimetre) in the final answer.
Therefore, the area of the book is equal to 144 square centimetres.
∴ A = 144cm2
Now, let us convert the value of area of the book in terms of its SI unit i.e. square metre.
We know,
1 square metre is equal to 10000 square centimetres.
1 m2= 10000cm2
As we need to convert the square centimetre value of areain terms of square metre, let us write the square centimetre value at first.
10000square centimetres is equal to 1 square metre.
10000cm2= 1 m2
Now, we can apply simple unitary method to get the value of 1 square centimetre in terms of metre.
1 square centimetre is equal to ten thousandth square metre
1 cm2 =As we need the area of the book (i.e. 144 square centimetres) in terms of its SI unit, let us multiply 144 by the unit value of square centimetre in terms of square metre.
144 cm2 = 144 ×Dividing 144 by 10000, we get 0.0144.
Therefore, the area of the book in terms of its SI units is equal to 0.0144 square metres.
Area = 0.0144 m2
Now, let us calculate the volume of the book (V).
We know,
Volume of book (V) is the product of its length (l), breadth (b) and height (h).
V= l × b × h
Substituting the given values in the formula
V= l × b × h
We get,
V is equal to
Let us write 18 in the place of ‘l’, 8 in the place of ‘b’ and 5 in the place of ‘h’.
Remember that it is not necessary to write the units while performing the calculations.
V = 18× 8 × 5
Multiplying 18, 8 and 5 together, we get 720.
V = 720
Remember that we should not forget to write the unit while writing the final answer.
So, let us write the unit of volume (cubic centimetre) in the final answer.
Therefore, the volume of the book is equal to 720 cubic centimetres.
∴ V = 720 cm3
Now, let us convert the value of volume of the book in terms of its SI unit i.e. cubic metre.
We know,
1 cubic metre is equal to one million cubic centimetres.
1 m3= 1,000,000cm3
As we need to convert the cubic centimetre value of volume in terms of cubic metre, let us write the cubic centimetre value at first.
One million cubic centimetres is equal to 1 cubic metre.
1000000cm3= 1 m3
Now, we can apply simple unitary method to get the value of 1 cubic centimetre in terms of cubic metre. This gives us
1 cubic centimetre is equal to one millionth cubic metre
1 cm3 =As we need the volume of the book (i.e. 720cubic centimetres) in terms of its SI unit, let us multiply 720 by the unit value of cubic centimetre in terms of cubic metre.
720 cm3= 720 ×Dividing 720 by 1,000,000, we get 0.000720.
Therefore, the volume of the book in terms of its SI units is equal to 0.000720 cubic metres.
Volume = 0.000720 m3
Hence, the area and volume of the given book are 0.0144 m2and 0.00072m3 respectively.
Mathematically,
Work output = Work input (In a balanced state of a lever)
Or, L х Ld = E х Ed
We have,
MA =
Mechanical advantage of a machine is 4 which means that the machine can lift load four times greater that the applied force.
Load distance (Ld) = 20 cm =
Effort (E) = 200 N
Effort distance (Ed) = 80 cm = 0.8 m
Mechanical advantage (MA) =?
Velocity ratio (VR) =?
Efficiency (ɳ) =?
We have,
MA = L/(E ) =
Again, VR =
Finally,
Efficiency =
Hence, MA, VR, and efficiency of the lever is 3, 4 and 75% respectively.
Work (W) = Force (F) х Displacement (d)
Force is expressed in N and distance is expressed in metre, then, work done is expressed in Nm. Newton metre is also called Joule. In short, it is represented by 'J'.
If F = 1N and d = 1 m,then,
W = 1 N х 1 m = 1 Nm = 1J
Hence, 1 joule of work is said to be done if a force of 1 N displaces a body by 1 m distance in the direction of force applied.
Rotating fan and stretched rubber contains kinetic energy and potential energy respectively.
The distance between two consecutive compressions or rarefactions of a sound wave is called wavelength of that wave. It is denoted by 'ʎ'.
Group (Chemistry)
Application of sulphuric acid
It is used in manufacture of chemical fertilizers, like ammonium sulphate, superphosphate.
Molecular formula of sodium hydroxide is NaOH.
Word equation-
Hydrogen + Oxygen → Water
Chemical equation-
2H2 + O2 → 2H2O
i. Paper chromatography
ii. Adsorption chromatography
| Protons | Electrons |
|---|---|
| They are positively charged particles. | They are negatively charged particles. |
| They are found in nucleus. | They revolve around nucleus. |
Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.
Acid is a chemical compound which gives hydrogen ion (H+) when dissolved in water. One molecule of sulphuric acid gives two hydrogen ions (2H+) when dissolved in water. Hence, sulphuric acid is called an acid.
Group (Biology)
The two function of epithelial tissue are:
i. To protect skin.
ii. Absorption of intestinal lining.
i. Brain
a. Thinking or cognition
b. Perception or sensing
ii. Spinal cord
a. Reflexes
b. walking
Beaker, funnel, test tube, hydrilla plant.
Procedure:
Take some healthy, fresh branches of hydrilla plant in a funnel and invert in a beaker. Put water in the beaker till the end of the funnel is under water as shown in figure. Take a test tube full of water and close its mouth with a thumb. Then invert it over the stem of funnel and release the thumb. Such method is applied so as to keep the test tube free of air. Keep the set undisturbed in the sunlight for a while.
Observation:
After a short time some bubble of gas in the test tube is produced. The gas so evolved is collected at the top of test tube. Take it out and bring burning match stick near the tube. The test-tube will steak light.
Figure in copy
Fig: Oxygen is evolved during photosynthesis.
Result
The evolved gas is oxygen which helps in burning.
Conclusion
O2 is evolved during photosynthesis.
Group (Astronomy and Geology)
In Nepal monsoon comes from south east of Nepal. During the summer, the water vapour rising from Bay of Bangal enters to Nepal from eastern part and flows towards the north and the west. When this vapour reaches in northern hills, it turns into rain and causes rainfall. Due to which eastern part of Nepal receives more rain that western in summer.
i) Minerals are crystalline in form.
ii) Every mineral has its own colour. For example, hematite has red-brown colour whereas chalcopyrite has golden green colour.
iii) Minerals are hard solid substances.
iv) Minerals shine according to their properties.
Group (Environment Science)
i. Forest protects us from bad weather and unpleasant consequences.
ii. Forest provides shelter and food to wildlife.
iii. Human beings depend upon forest for firewood, fodder, medicinal herbs, etc.
iv. Industries get their raw materials from the forest.
i. Water vapour
ii. Carbon dioxide
iii. Methane
iv. Ozone
A labeled diagram of soil profile is as follows:
Fig: Soil profile