These questions are actually pretty easy, if you really are struggling, you can do a little research
Answer:
Water-lifting devices are used to lift water to a height that allows users easy access to water. ... Other devices, such as the air-lift pump, are not included because they are not applicable to drinking-water supply systems. 4.2 Rope and bucket1. 4.2.1 The technology. This device is mainly used with hand-dug wells.
Answer:
Value of 
Explanation:
We have given
In first case resistance is
and current is 1.8 A
Let the potential difference is v
So
----eqn 1
In second case resistance is
and current is 1.6 A and potential difference will be as it is a series connection
So
----eqn 2
From eqn 1 and eqn 2

