The heat and energy of coal burning is more easier and more efficient to turn into electricity than any method using renewable resources.
Explanation:
Given that,
Wavelength of the light, 
Work function of sodium, 
The kinetic energy of the ejected electron in terms of work function is given by :
The formula of kinetic energy is given by :
Hence, this is the required solution.
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.
The planet MARS is visible without a telescope on many clear nights. The planets JUPITER, MERCURY, VENUS and SATURN are also viewable without the aid of magnification.
