D. It must be able to be magnetized
Explanation:
The requirement for a core to be used in an electromagnet is that it must be able to be magnetized.
An electromagnet is a type of magnet produced by electricity.
- They typically run and produce magnetic fields in the vicinity of electrical currents.
- These magnets are not permanent magnets.
- When the electrical current is removed, the magnetic property of the substance is lost.
- The core of an electromagnet is usually made up of a material that can easily be magnetized in the presence of magnetic fields.
- Some of the materials used are cobalt, iron, nickel.
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Answer:
a) equal 1, b) less than 1
Explanation:
a) the electric force is given by
Fe = q E
The charge of the electron and proton has the same value, that of the proton is positive and that of the electron is negative
Proton
Fp = qE
Electron
Fe = - q E
Fp / Fe = -1
If we do not take into account the sign the relationship is equal to one (1)
b) to calculate the force we use Newton's second law
F = ma
qE = m a
a = q E / m
The mass of the proton much greater than the mass of the electron
ap = q E / 
ae = - q E / 
ap / ae =
/
=
/1600
=1/1600
It is much smaller than 1
4 earth years is the answer
Explanation:
In order to calculate the force, we will use the following formula.
F = 
where, 
r = 
Therefore, we will put the given values into the above formula as follows.
F = 
= 
=
N
Thus, we can conclude that the given two grains will repel each other by a force of
N.