NCTB Class 7 Science Chapter Ten Exercise 10 Solution by Science Expert. Bangladesh Board Class 7 Science Solution Chapter 10‘’Phenomena of Electricity and Magnet’’ Exercise 10 Solution.
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Board |
NCTB |
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Class |
7 |
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Subject |
Science |
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Chapter |
10 |
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Chapter Name |
‘’Phenomena of Electricity and Magnet’’ |
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Exercise |
10 Solution |
Exercise: 10
Fill in the blanks:-
(1) —– moves round the nucleus.
Answer:- Electons.
(2) Semi-conductors generally behave like — in low temperature.
Answer:- Non-conductor.
(3) The behaviours a — in a globe is similar to the behaviour of — magnets.
Answer:- Bar magnet.
Short answered questions:-
(2) How does electric bulb spread light?
Answer:- Bulb produces a lot of heat when it is connected with the electric source and the filament of bulb emits a huge amount of light. That’s how electric bulb spread light.
(3) How can magnetic substance be transformed into magnet?
Answer:- Magnetic substances can be transformed into magnet by rubbing and electrical method.
Multiple choice questions:-
(1) The aim of using regulator in electric fan is to —
Answer:- (c) Control motion.
(2) Based on the properties of magnets which of the following substances belong to same group?
Answer:- (b) Cobalt, iron, nickel.
Observe the following figures carefully and answer the question no. 3 and 4.
Creative question:-
(1) Simiha has a bare magnet. She prepared a magnet by rubbing method and another by electrical method.
(a) What is called magnetic substance?
Answer:- Which substances are attracted by the magnet are called magnetic substances. E.g.: iron, nickel, cobalt etc.
(b) Explain that the earth is a huge magnet.
Answer:- The two poles of hanging bar magnet indicates two poles of Earth’s magnet. Here the north pole of bar magnet indicates the north side. But a north pole always attracts a south pole. Therefore the south pole of Earth’s magnet works as north pole.
(c) Describe the first method of preparing magnet.
Answer:- The first method of preparing a magnet is rubbing method. For this method we need a bar magnet and a steel bar. By rubbing the steel bar from one to another end with a pole of bar magnet for several times the steel bar converted into a magnet
(d) “ The second type of magnet is strong thought temporary” – analyze the quotation.
Answer:- “The second type of magnet is strong though temporary” – The strength of this magnet depends on the flow electric current through it. So if we supply more amount of electric current through it then it became more powerful magnet.
(2) (a) What is called static electricity?
Answer:- Until the electricity does not flow from one place to another or one to another through a medium, it is called static electricity.
(2) (b) Why metals are conductor of electricity? Explain.
Answer:- Metals are conductor of electricity because the electrons of metals can move from one atom to another easily and metals are good conductor.
(2) (c) Explain the function of the figure 1?
Answer:- The function of the figure 1: This produces a lot of heat when it is connected with the electric source and the filament of the figure 1 emits a huge amount of light.
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