A small region between two very large parallel metallic plates is maintained in a uniform electric field that points horizontally from left to right.
(i) What is meant by a "uniform electric field"? State one practical arrangement that produces such a field in a laboratory.
(ii) A point charge +Q is suddenly introduced at the centre of the region. Describe qualitatively how the pattern of electric field lines in the region is altered. Draw a neat, labelled sketch of the field lines to support your description.
(iii) Explain why the field pattern you have drawn approaches the original straight, parallel lines at sufficiently large distances from the point charge.