Self-made telephone has the best communication effect in () and ().

The self-made telephone has the best communication effect under the conditions of (tightening the long line) and (line length 1 meter).

Making simple telephone (scientific experiment);

Step 1: fix the paper clip at one end of the line;

Step 2: thread the needle and thread out of the bottom of the paper cup;

Step 3: put it in from the bottom of another paper cup;

Step 4: Remember to tie a paper clip inside the paper cup;

Step 5: Draw a lovely pattern on the paper cup with a colored pen, and the phone will be ready.

The secret of the experiment:

In the experiment, sound travels through cotton thread much faster than in air. Try to stand at a distance of 0/0 meter from your friend/kloc-and remember to straighten the line.