Electricity Worksheet-16

Electricity Worksheet-16

 

  1. Why is tungsten used almost exclusively for filament of incandescent lamps ?

 

  1. Why are the conductors of electric heating devices, such as toasters and electric irons, made of an alloy rather than a pure metal ?

 

  1. Why is the series arrangement not used for domestic circuits ?

 

  1. How does the resistance of a wire vary with its cross-sectional area ?

 

  1. Why are copper and aluminium wires usually employed for electricity transmission.

 

  1. What is meant by quantization of charge ?

 

  1. What is an electric current ? Give its SI unit.

 

  1. What is represented by joule/coulomb ?

 

  1. A charge of 2 C moves between two plates, maintained at a potential difference of 1V. What is the energy acquired by the charge ?

 

  1. Why are copper wires used as connecting wires?

 

Answer:

  1. Tungsten has a high melting point (3380°C) and it becomes incandescent or it emits light at a high temperature at around  2400 K.

 

  1. The resistivity of an alloy is generally higher than that of pure metals of which it is made of.

 

  1. In series arrangement, in case any one of the appliances fails or is switched off, all the other appliances stop working because the same current is passing through all the appliances.

 

  1. The resistance of a wire (R) varies inversely as its cross-sectional area (A) as R ∝ 1/A.

 

  1. Copper and Aluminium wires possess low resistivity and as such are generally used for electricity transmission.

 

  1. A charged body has only integral multiples of electronic charge on it, i.e.,

          Q = ne where n = ± 1, ± 2, …

 

  1. The ordered flow of electric charges through a conductor is called electric current and it is equal to charge flowing per unit time, current = charge/time. Its SI unit is an ampere (A).

 

  1. It is SI unit of potential difference, i.e., volt.

 

  1. Energy acquired, W = QV = 2C × 1V = 2 J.

 

  1. The electrical resistivity of copper is low.