Gravity pulls objects down to the earth
Answer:
Wind the long piece of thin wire around the uniform glass rod multiple times, find the length of the total diameters using the metre ruler, and divide by the number of times you wound it around the rod.
Explanation:
Since the diameter of one long piece of thin wire is too thin to be measured by a metre ruler, you can wind it multiple times and push it side by side to get a length you can measure.
For example, if you wound it around 20 times and the total length of 20 diameters of the wire side-by-side is 2.0 cm, one winding, which is the diameter would be 2.0cm ÷ 20 = 0.10cm or 1mm.
Answer: 
Explanation:
The diffraction angles 
when we have a slit divided into 
parts are obtained by the following equation:
(1)
Where:
is the width of the slit
is the wavelength of the light
is an integer different from zero.
Now, the second-order diffraction angle is given when 
, hence equation (1) becomes:
(2)
Now we have to find the value of 
:
(3)
Then:
(4)
(5)
Finally:
(6)
