Chapter - Electricity
1. By what other name is the unit joule/coulomb is called?
Ans: Volt
2. Which of the following statements correctly defines a volt?
(a) a volt is a joule per ampere.
(b) a volt is joule per coulomb.
Ans: Option (b)
3. What is meant by saying that electric potential at a point is 1 volt?
Ans: `The electric potential at point is said to be 1 volt if 1 joule of work is done in moving 1 coulomb of electric charge from one point to that point.
4. How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V?
Ans: Potential difference = Work done/Charge moved
Work done = potential difference x charge moved
= 12 x 2
= 24 J - Ans
5. Fill in the blanks with suitable words:
(a) Potential difference is measured in .................... by using a ............. placed in
................. across a component.
(b) Copper is a good ................, Plastic is an ................. .
Ans : (a) volt, voltmeter, parallel
(b) conductor, insulator
6. What do you understand by the term "electric potential"? What is the unit of electric potential?
Ans: The work done in moving a unit positive charge from infinity to a point is defined as electric potential at that point.
The unit of electric potential is "Volt".
7. (a) State the relation between potential difference, work done and charge moved.
(b) Calculate the work done in moving a charge of 4 coulombs from a point at 220 volts to another point at 230 volts.
Ans: (a) The relation between potential difference, work done and charge moved is
Potential difference = Work done/charge moved
(b) Charge = 4 coulomb ; P.d = (230 - 220) volts
= 10 volt
Work done = P.d x charge
= 10 x 4
= 40 J - Ans
8. State whether a voltmeter has a high resistance or a low resistance. Give reason for your answer.
Ans: Voltmeter has high resistance so that it takes negligible current from the circuit and less current passes through it and the current reading of the voltage can be taken.
9. One coulomb charge is equivalent to the charge contained in :
Ans : 6.25 x 10^18 electrons
10. The atoms of copper contains electrons and the atoms of rubber also contains electrons. Then why does copper conduct electricity but rubber does not conduct electricity?
Ans: The presence of free electron in any substance makes it a conductor of electricity. Now the atoms of copper contains free electrons while the atoms of rubber do not contain free electrons.
Therefore copper conduct electricity and rubber do not.
Note: The above questions have been taken for the practice purpose of students from the book "Science for Tenth Class Part - 1 Physics" by Lakhmir Singh and Manjeet Kaur
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