E=hv is an equation important when dealing with light. E refers to the energy of a photon; h is Planck's constant and v is the wavelength. According to this equation, light particles called photons travels in packets of energy. This is important in pv cells because this is the technology used to harness solar energy which is converted to electricity. The amount of energy should be estimated to know the appropriate material of construction of the pv cell to achieve optimum conditions. In this way, the pv cell could maximize the sun's energy.
The right answer is B.
Cholera vaccination is only recommended for staff who have to intervene with patients in an epidemic situation. In all other cases, effective prevention is provided by good personal hygiene (washing hands) and food.
It is also important to know that this vaccine does not protect permanently: It protects only about 90% within 6 months, then to 50% within 3 years.
