(a) 
The relationship between frequency and wavelength of an electromagnetic wave is given by

where
is the speed of light
is the frequency
is the wavelength
In this problem, we are considering light with wavelength of

Substituting into the equation and re-arranging it, we can find the corresponding frequency:

(b) 
The period of a wave is equal to the reciprocal of the frequency:

And using
as we found in the previous part, we can find the period of this wave:

Answer:
(for small oscillations)
Explanation:
The total energy of the pendulum is equal to:

For small oscillations, the equation can be re-arranged into the following form:

Where:
, measured in radians.
If the amplitude of pendulum oscillations is increase by a factor of 4, the angle of oscillation is
and the total energy of the pendulum is:

The factor of change is:


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