When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
Solution and Explanation
The deflection of magnetic needle indicates electric current is flowing through the wire. It means the liquid or the solution is a good conductor of electricity. When the free ends of a tester are dipped into a solution, electric circuit is completed and an electric current passes through the solution.
Top Questions on Chemical Effects of Electric Current
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Questions Asked in CBSE Class VIII exam
Underline the verbs and arrange them in two columns, Past and Earlier past.
(a) My friends set out to see the caves in the next town, but I stayed at home, because I had seen them already.
(b) When they arrived at the station, their train had left. They came back home, but by that time I had gone out to see a movie!
(c) So they sat outside and ate the lunch I had packed for them.
(d) By the time I returned, they had fallen asleep!
Past Earlier Past - CBSE Class VIII
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Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.
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- Match the organisms in Column A with their action in Column B.
A
B
(i) Bacteria (a) Fixing nitrogen (ii) Rhizobium (b) Setting of curd (iii) Lactobacillus (c) Baking of bread (iv) Yeast (d) Causing malaria (v) A protozoan (e) Causing cholera (vi) A virus (f) Causing AIDS (g) Producing antibodies - CBSE Class VIII
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Say whether the following are true or false.
1. Ignesious lost his wife, two children, his father-in-law, and his brother-in-law in the tsunami.
2. Sanjeev made it to safety after the tsunami.
3. Meghna was saved by a relief helicopter.
4. Almas’s father realised that a tsunami was going to hit the island.
5. Her mother and aunts were washed away with the tree that they were holding on to.
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Concepts Used:
Electric Current
Defining Electric Current
It is the rate of flow of electrons in a conductor. SI Unit - Ampere (A).
Electrons are negatively charged particles hence when they move a number of charges moves.
Note:- The ability of a particular substance to conduct electricity depends on the number of electrons that are able to move . Some of the materials allow current to flow better than others.
What is an Electromotive Force?
If a force acts on electrons to make them move in a particular direction, then up to some extent random motion of the electrons will be eliminated. An overall movement in one direction. The force which acts on the electrons to move them in a certain direction is known as electromotive force and its quantity is known as voltage and is measured in V.