In: Physics
A metallic wire of length L and diameter d is covered with a very thin isolating layer. The resistivity of the metal is ρ (rho) and the wire has resistance R. When a battery with voltage V is connected to the ends of the wire a current I flows through it.
a)Find an equation for the resistivity ρ (rho) in terms of the variables provided.
b)For a wire of length 24.5 m and diameter 0.5 mm, calculate the resistivity (in Ωm) assuming that the current is 4.5 A when a 9-V battery is connected to the wire.
c)Write an equation for the power and calculate its value.
d)As current flows the wire heats up. How does this affect the resistance of the wire and the power, assuming the wire stays connected to the same battery.
a)The resistance increases and the power increases.
b)The resistance decreases and the power increases.
c)The resistance increases and the power decreases.
d)The resistance decreases and the power decreases.
e) The wire is made into a single layer, tightly wound solenoid and connected to the same battery as before. Write a symbolic equation for the magnetic field of the solenoid and calculate its value.