Why does the sample on a microscope slide need to be very thin?
2 answers:
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Answer:
a) - the resistance is proportional to the length of the metal
- a thicker rod, since resistance decreases with increasing area
b) The current is proportional to the area so this is the factor that is influenced by the electric field
Explanation:
a) When the rod is connected to the rod an electrical circuit described by the expression is formed
V = I R
I = V / R
The resistance of the rod is
R = ρ L / A
Where ρ is the resistivity of metal, L Longitud and A cross section.
If a higher current is measured when the other rod is connected, it implies that the resistance has decreased. To have a decrease in resistance you have two possibilities
- use a shorter rod, since the resistance is proportional to the length of the metal
- Use a thicker rod, since resistance decreases with increasing area, remember that the area of a circle is
A = π R²
Therefore, small increases in the diameter of the rod could give great changes in resistance.
b) The current is defined with the charge that crosses a surface per unit of time, when the electric field increases the electrons feel a greater force, therefore the current increases.
The charge number on a wire is
Q = q n Δt A
So up to date is
I = q n When the rod is connected to the rod an electrical circuit described by the expression is formed
V = I R
I = V / R
The resistance of the rod is
R = rho L / A
Where rho is the resistivity of metal, L e; Long and A cross section.
If a higher current is measured when the other rod is connected, it implies that the resistance has decreased. To have a decrease in resistance you have two possibilities
.- use a shorter rod, since the resistance is proportional to the length of the metal
. - Use a thicker rod, since resistance decreases with increasing area, remember that the area of a circle is
A = pi R2
Therefore, small increases in the diameter of the rod could give great changes in resistance.
.b) The current is defined with the charge that crosses a surface per unit of time, when the electric field increases the electrons feel a greater force, therefore the current increases.
The load number on a wire is
Q = q n Dt A
So current is
I = q n v_{d} A
The drag speed (v_{d}) is constant in the materials, it depends on the purity and imperfections, so a change in the length does not significantly change the current.
The current is proportional to the area so this is the factor that is influenced by the electric field
The drag speed (vd) is constant in the materials, it depends on the purity and imperfections, so a change in the length does not significantly change the current.
The current is proportional to the area so this is the factor that is influenced by the electric field