Is it necessary to have many slides when presenting in conference, if the speaker can clearly present his or her research with only just a few slides? How to decide when to use or not to use the slide? Science and engineering fields of research are preferred.
Slides serve the following purposes:
- If the title of your paper is too long, you don't have to write the title on the board, losing time.
- They keep the audience up-to-date. Gives an idea on what you are doing now, what you are going to do some time after.
- Contains hard-to-draw figures. Therefore, you are able to talk to-the-point without losing time on drawing figures.
- Contains experimental results. These, if extensive, literally cannot be drawn accurately onto board in about 10 minutes. Maybe they can be, but then there is no time to talk.
- May serve you as reminder cards, therefore you don't forget what to talk about 2 minutes later.
- In the Q&A session, if someone asks you about a table, a figure or a graph, you don't have to draw them again. Rather, you can just go back and answer the question.
- If you are a junior researcher, you are able to write your name and affiliation on the slides, and avoid the awkwardness of writing your name on the board as if you're an instructor and if audience consists of students.
- You can always support slides by using the board, and explain your points better.
These being stated, I think slides are crucial for a presentation where the time limit is considerably low (10-20 minutes including Q&A).
In my field (mathematics) and in my experience it is more common to use slides for conference talks than not, but a significant number of talks use a chalkboard or whiteboard, so it is certainly not necessary to use slides. (By `slides' I mean projected electronic files, such as beamer or powerpoint, not acetate sheets)
I might add my impression that if anything talks that eschew slides are considered better than those that use them. However whether a speaker uses slides depends on other factors such as the duration of the talk: the longer the talk the better the opportunity to give a board talk.
(And I agree with comments above that applause per se is rarely the primary aim of a speaker or the measure of a good talk.)