Answer: section 2 and 4
Explanation:
I had this problem before and that was the answer.
A magnetic field is produced by moving electric charges so B
Answer:

Explanation:
v = Velocity of the breeze = 4 m/s
w = Width of the valley = 5000 m
h = Height of the valley = 1000 m
Volumetric flow rate is given by

= Mass flow rate of pollutant = 25 g/s = 
Concentration is given by

The steady state concentration of pollutants in the valley, is
.
Answer:
The electromagnetic force
Explanation:
The electromagnetic force is one of the four fundamental forces of nature. Namely, they are:
- Electromagnetic force: it is the force exerted between electrically charged particles (and between magnetic fields). The force can be either attractive (if the two charges have opposite signs) or repulsive (if the two charges have same sign), and it acts over an infinite range.
- Gravitational force: it is the force exerted between objects with mass. It is always attractive, and it also has an infinite range of action. It is the weakest of the four fundamental forces.
- Strong nuclear force: it is the force that acts between protons and neutrons inside the nucleus, and it is responsible for keeping the nucleus together and preventing it from breaking apart (due to the electrostatic repulsion between protons)
- Weak nuclear force: it is the force responsible for certains nuclear decays, such as the beta decay, in which a neutron turns into a proton, emitting an electron and an antineutrino.
B
V= f x lambda
V= 5m/s
F = 10hz
Lambda = ?
5 = 10 x lamba
5 /10 = lambda
Wavelength =0.5