"<em>The different types of radiation are defined by the the amount of </em><em>energy</em><em> found in the photons. Radio </em><em>waves</em><em> have photons with low energies, microwave photons have a little </em><em>more energy</em><em> than radio </em><em>waves</em><em>, infrared photons have still </em><em>more</em><em>, then visible, ultraviolet, X-rays, and, the </em><em>most</em><em> energetic of all, gamma-rays.</em>"
The neutral pH is 7. Less than 7 indicates an acid and more than 7 indicates a base (up to 14).
<span>
NaCl - it's a salt (we can't measure the pH)
H2O - it can be an acid but also a base (the pH it is almost neutral,meaning close to 7 )
HF - it is a strong acid
</span><span>
KOH
- it is a strong base (pH=14)
</span>
↓
He needs to use HF (Hydrogen fluoride) to decrease the pH.
The evidence that the universe is expanding comes with something called the red shift<span> of light. Light travels to Earth from other galaxies. As the light from that galaxy gets closer to Earth, the distance between Earth and the galaxy increases, which causes the wavelength of that light to get longer.</span>
Missing questions: "find the speed of the electron".
Solution:
the magnetic force experienced by a charged particle in a magnetic field is given by
where
q is the particle charge
v its velocity
B the magnitude of the magnetic field
the angle between the directions of v and B.
Re-arranging the formula, we find:
and by substituting the data of the problem (the charge of the electron is
), we find the velocity of the electron: