A right triangle ABC has sides /AB/ =9cm, /BC/=12cm find /AC/ and angles ACB and ABC if angle BAC= 90°
1 answer:
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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
1. False
Explanation: it's exactly the opposite. In fact, Lenz's law states that the induced current and the induced emf in a conductor are generated in such a direction that opposes to the change in magnetic flux through the coil. This is summarized by the negative sign in the Faraday's Newmann Lenz law:
where is the emf induced and
is the rate of change of magnetic flux through the coil.
Lenz's law is a consequence of the law of conservation of energy. In fact, we have:
- If the magnetic flux through a coil is increasing, then the induced current has a direction such that the magnetic field generated by the coil is opposite to the direction of the external magnetic field, in order to decrease the total flux
- If the magnetic flux through a coil is decreasing, then the induced current has a direction such that the magnetic field generated by the coil is in the same direction as the external field, in order to increase the total flux
2. False
Explanation: the magnetic flux through a surface is given by
where
B is the magnitude of the magnetic field
A is the surface area
is the angle between the direction of B and the normal vector to the surface
As we see, the magnetic flux depends not only on B and A, but also on the orientation of the coil with respect to the magnetic field.
3. False
Explanation:
- Sound waves are mechanical waves: mechanical waves are waves consisting of oscillations of the particles in a medium. Due to their nature, therefore, mechanical waves can propagate only in the presence of a medium
- Electromagnetic waves are NOT mechanical waves: they consist of oscillations of electric and magnetic fields, in a direction perpendicular to the direction of propagation of the wave. Since em waves are not mechanical waves, they do NOT need a medium to propagate, since they can also travel through a vacuum; therefore the original statement is false.