A wire made of nickel has 50 m long and 0.5 mm in diameter. between the ends of this wire is applied a potential difference of 110 volts. The electrical resistivity of nickel is 0.342 Ω.mm².m⁻¹. Determine:
a) The electrical conductivity of nickel;
b) the resistance of wire;
c) the conductance of it;
d) the intensity of the current;
e) The absorbed power.
f) the energy absorbed in 1 hour;

A 100-ton electric locomotive is driven by four electric engines operating with a potential difference of 1000 volts and moves at a speed of 72 km/h. Assuming the friction coefficient between the wheels of the locomotive and the rails equal to 0.5 and the free-fall acceleration g=10 m/s², determine:
a) The electric current circulating on each engine;
b) If in each engine we have a current equal to 4000 amperes, how many railroad cars, 15 tons each, will the locomotive be able to pull?

A wire with cross-sectional 0.50×10⁻² cm², conducts a direct current equal to 4.0 A, given the elementary charge 1.6×10⁻¹⁹ C, determine:
a) The number of electrons passing through a cross-section per second;
b) The average speed of electrons, knowing that there are 1.8×10²⁰ electrons/cm³.

Inside a container with 0.5 kg of water is placed a resistor with 2 Ω of electrical resistance conducting an electric current of 5 A for 7 min. Calculate the water temperature rise, assuming there is no change in state. Data: the specific heat of water is equal to 1 cal/g°C and mechanical equivalent of heat 1 cal = 4.2 J.

Suppose that from each group of s atoms of a metal sample, it is possible to remove f electrons. Consider a block of mass m. Assume M is the molecular mass of the metal. What will be the charge of this block if we remove f electrons?