<h3><u>Answer;</u></h3>
Period = 1/17 seconds
<h3><u>Explanation;</u></h3>
- Wavelength is related to period by the expression:
<em>speed = wavelength / period
</em>
- If we are given the speed, then we can easily calculate the period at the wavelength of 20 m.
<em>Given the speed of sound wave as 340 m/s </em>
<em>Period = Wavelength/ speed</em>
<em> = 20 m/340 m/s</em>
<em> </em><u><em>= 1/17 seconds</em></u>
In a direct current, the electric charge, or current, only flows in one direction. In an alternating current, the electric charge changes periodically.
Answer:
Hipparchus was an ancient Greek who classified stars based on the brightness in 129 B.C. He grouped the brightest stars and ranked them 1 (first magnitude) and dimmest stars as 6 (sixth magnitude). Thus, the smaller numbers indicated brighter stars. Now, the scale extends in negative axis as well. More the negative number, brighter is the star. For example, Sun has magnitude -26.74.
This the apparent magnitude which means the classification is based on the brightness of the star as it appears from the Earth.
