What is a dry cell ? …

A dry cell is a voltage generating cell in which the electrolyte is in the form of a moist paste. Because of this there is no spilling of electrolyte and hence becomes portable. This is used in torch lights, portable radios, etc.  Zinc-Carbon batteries and alkaline batteries are examples of dry cells.
A dry cell consists of a metal electrode or graphite rod surrounded by a moist electrolyte paste enclosed in a metal cylinder as shown here. Different chemicals can be used to create this paste, such as ammonium chloride and manganese dioxide, depending on the type of battery. The cathode and electrolyte paste are wrapped in paper or cardboard and sealed into a metal cylinder called an anode, which is made of zinc.
The anode in the dry cell battery has two terminals, one that is positive and one that is negative. When a load is connected to the battery's terminals, a chemical reaction occurs between the anode and the paste that produces roughly 1.5 volts of electricity. A pin or collector in the middle of the battery conducts this charge out of the battery to an external circuit. This circuit physically connects to the electronic device the battery is in, providing the charge necessary for the device to function.