Science homework
1.explain working of torch.
2.explain dry cell with diagram.
Answers
.1.The batteries supply this current. As soon as the torch is switched on, the chemical present inside the batteries produces an electric current. These batteries are connected to the bulb with the help of a switch. A curved mirror is situated behind the bulb which reflects the light of the bulb in the form of a beam.
2.Dry Cell : It is a primary cell based on Leclanche cell invented by G. Leclanche in 1868. In a primary cell, the electrode reactions cannot be reversed by an external source of electrical energy. In this cell, the cell reaction takes place only once i.e., this cell is not rechargeable. It is.generally used intorched, transistors, radios, calculators, tape recorders etc. It consists of a hollow zinc cylinder which is filled with a paste of NH4Cl nad a little ZnCl2. This paste is made with the help of water. The zinc cylinder acts as anode while cathode is a graphite rod (Carbon). The carbon rod is surrounded by a black paste of MnO2 and carbon powder. The zinc cylinder has an outer insulation of cardboard case.
Dry cells are sealed with wax or other material to protect the moisture from evaporation. When the electrodes are connected, the cell operates.
The electrode reactions are complex. Metallic Zn is oxidized to Zn2+ and the electrons liberated are left on the container. The reactions which take place at electrodes can be represented as :
At anode : Zn(s)→Zn(aq)2++2e− (Oxidation)
At cathode : 2NH4(aq)++2MnO2(s)+3e−→Mn2O3(s)+H2O(I)+2NH3(g)(Reduction)
Answer:
I hope this helps.
Explanation:
1)Working of torch
There are two dry cells, A switch and a lamp. In the torch,pushing the switch completes the circuit and allows current to flow. The lamp and the reflector focus on the light into a narrow beam. The plastic casing is an electrical insulator.
2)Dry Cell
The source of electric current in a torch is a dry cell. They have different sizes and different capacities. Each cell has 2 terminals positive (marked +) and negative (marked -). In dry cells chemicals are stored, which react and produce electricity. This runs the electrical devices. When these chemicals are used up or exhausted, we have to throw away the cell. Two or more cells connected together is called a battery.
