<span>The correct option is D) both A and B. In fact, the strength of an electric field produced by a single point charge is given by
</span>

<span>
where Q is the charge that generates the field, k is the Coulomb's constante and r is the distance from the charge source of the field.
From the equation, we see that the strength of the field depends on A) the amount of charge that produced the field (Q) and B) the distance from the charge (r), so the correct option is D.</span>
Explanation:
velocity = wavelength × frequency
3×10⁸ = 400/10⁹ × frequency
frequency = 3 × 10¹⁵ /400
frequency = 75×10¹¹Hz
Explanation:
All the energy in oil, gas, and coal originally came from the sun captured through photosynthesis. In the same way that we burn wood to release energy that trees capture from the sun, we burn fossil fuels to release the energy that ancient plants captured from the sun.
At First, there is chemical Energy( in your muscels) which is Used to Push down the spring. This Energy becomes the Energy of the spring, which increases until you stop pushing. If you Put your hand away, the Energy of the spring will become kinetic energ. This Energy is at the highest Level the Moment the book ist Leaving the spring. Afterwards, the kinetic Energy decreases while the Gravitational Potential Energy increases.