Electricity Worksheet-12

Electricity Worksheet-12

 

  1. An electric kettle is rated at 230 V, 1000 W. What is the resistance of its element ? What maximum current can pass through its element?

 

  1. Two bulbs A and B are rated 100 W – 120 V and 10 W - 120 V respectively. They are connected in parallel across a 120 V source. Find the current in each bulb. Which bulb will consume more energy?

 

  1. What does an electric circuit mean ?

 

  1. Define the unit of current.

 

  1. Calculate the number of electrons constituting one coulomb of charge.

 

  1. Name a device that helps to maintain a potential difference across a conductor.

 

  1. What is meant by saying that the potential difference between two points is 1 V ?

 

  1. How much energy is given to each coulomb of charge passing through a 6 V battery ?

 

  1. On what factors does the resistance of a conductor depend?

 

  1. Will current flow more easily through a thick wire or a thin wire of the same material when connected to the same source ? Why ?

 

Answer:

  1. As

         

 

  1. Resistance of bulb A, i.e.,

Resistance of bulb B, i.e.,

Current through bulb A, i.e.,

Current through bulb B, i.e.,

Bulb A  will consume more energy than the bulb A when these are connected in parallel.

 

  1. An electric circuit is a closed and continuous path through which an electric current flows.

 

  1. The SI unit of current is called an ampere (A). Current flowing through a conductor 1 ampere if 1 coulomb of charge flows through it in 1 second, i.e.,

      

 

  1. The charge on an electron, e = 1.6 × 10–19 C. Number of electrons constituting 1 coulomb is :

         

 

  1. A battery (consisting of one or more electric cells) is used to maintain a potential difference across a conductor.

 

  1. Potential difference between two points in a current-carrying conductor is 1 volt if 1 joule of work is done to carry a charge of 1 coulomb from one point to the other, i.e.,

         

or     

 

  1. W = QV = 1C × 6V = 6J.

 

  1. The resistance (R) of a conductor depends upon :

(i) its length (l) where R ∝ l.

(ii) its cross-sectional area (A) where R ∝ 1/A.

(iii) resistivity (p) of its material where R ∝ p. Thus, R = p l/A.

 

  1. The current flows more easily through a thick wire than through a thin wire. This is due to the reason that the resistance R of a thick wire is less than that of a thin wire R ∝ 1/A. Thick wire has large cross section than thin wire.