I. Choose the correct answer. 8x1=8
1. The most suitable material for making the core of an electromagnet is
a)Brass b)Soft iron c)Aluminium d)Steel
2. An exam[le of analogous organ is
a)our arm and a dog’s foreleg b)our teeth and an elephant tusks
c)Potato and runners of grass d)Birds wing and insects wing
3. If one of the metals is mercury, then the alloy is known as
a)Blend b)Amalgam c)Soldering metal d)Brass
4. Male parts of the flower
a)Ovary b)pollen tube c)Petals d)Pollen grains
5. Which of the following is growth inhibitor of plant?
a)Auxin b)Gibberlin c)cytokinen d)Abs sic acid
6. Which compound undergoes chemical decomposition when exposed to sunlight
a)AgCl b)MgCl2 c)CaCl2 d)NaCl
7. Triad rule is proposed by
a)Newland b)Dobereiner c)Mendeleev d)Mosle
8. The defect of vision which cannot be corrected by using spectacles is
a)Cataract b)Myopia c) Hypermetropia d)Presbyo
Answers
Answer:
You can make an electromagnet stronger by doing these things:
wrapping the coil around a piece of iron (such as an iron nail)
adding more turns to the coil.
increasing the current flowing through the coil.
Materials used for making electromagnetsshould have best magnetising and demagnetising property. Among stainless steel, silver, soft iron and nickel, soft iron hasbest magnetising and demagnetising property. Therefore, soft iron is most suitable.
Explanation:
The most suitable material for making the core of an electromagnet is soft iron because its use as a core in a solenoid produces strongest magnetism.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.The strength of an electromagnet can be affected by various factors such as no. of coils, specific resistance of the wire used to coil the core, the thickness of the wire etc. ... Thus as resistance drops, more current will flow through the electromagnet causing a larger magnetic field.