Describe the systems of Petty cash?

following are the two kinds of petty cash systems

a) ordinary system- where petty cashier recieves a lumpsum amount of cash and when the whole amount is spent he submits the account to the head Cashier

b) Imprest system- a certain fixed amount is given to cashier for a specified period for a week or so and meets the petty cash expenses. after the time of a week or so provided to him, he submits the account of sum spent with supporting vouchers.