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1. Distinguish between static and electricity and current electricity?

The study of electric charges at rest is called ‘static electricity’. The study of various effects of electric charges in motion is called ‘current electricity’.

2. What is e. m. f. of a cell?

The e. m. f (electro motive force) is defined as amount of work done by the cell on charge carriers (electrons) to force them to go to the point of higher potential.

3. What do you mean by potential difference?

The potential difference between two points is said to be one volt, when one joule of work is done in carrying one coulomb of positive charge form one point to the other.

4. Define ampere.

Ampere is the amount of current in a conductor, when a net flow of charge per second through its cross section is one coulomb. 
Ampere= Coulomb/ Second.

5. How do you connect cells in series ? When they are connected in series and what is the total e.m.f of the combination?

When negative terminal of a cell connected to the positive terminal of the next cell, then the cells are said to be in series.
The total e.m.f (E) of the combination of three cells connected in series is sum of e.m.f’s of individual cells.

             E= E1+E2+E3

6. State Ohm’s Law.

The electric current (i) in a conductor is directly proportional to the potential difference (v) between its ends at a constant temperature (T).

     According to Ohm’s law, V= iR

7. State laws of resistance.

  • The resistance (R) of a conductor is directly proportional to the length of the conductor (l), R α l.
  • The resistance (R) of a conductor is inversely proportional to the area of cross section (A) of that conductor, Rα l/A. 

8. Distinguish between resistance and resistivity. 

Resistance is the property of opposing free flow of electrons. It is measured in ohms. Resistivity is an electrical property of a material. It is measured in ohm – metre. 

9. Write an expression for R and p of a substance. 

The resistance ( R) of a conductor is given by R = p * l /A(where p is specific resistance, l is the length of conductor and A is area of cross section of the conductor). 

10. What is the unit of specific resistance?

Unit of specific resistance is ohm- metre.

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