Department: Comm, Mech, Cont & Bio
Subject: Electrical Circuits
Academic Year : 2020-2021
Semester: Fall
Lecturer: Dr.Salah Alian
Sheet No: 1
Sheet(1)
Q1) A copper wire of 1 𝑚 length and 1 𝑐𝑚2 cross sectional area compute for the
wire resistance. The resistivity of copper is 𝜌𝑐𝑢 = 1.724𝑥10−8 Ω . 𝑚 .
Q2) A 5 m long copper conductor with circular cross section of 5 𝑚𝑚 in diameter
with specific resistance = 1.72 𝑥 10−8 Ω . 𝑚. Calculate the conductor resistance.
Q3) A 40m metallic conductor with a cross sectional area of 1 𝑚𝑚2 has resistance
of 12Ω . Calculate the conductivity of this metal.
Q4) Calculate the resistance of 100m length of wire with cross section are of
1 𝑚𝑚2 ,if the wire made of Manganine with a specific resistance of 50𝑥10−8 Ω . 𝑚.
Q5) A cube of an alloy with 2cm side has a resistivity of 1.12𝜇Ω . 𝑚
Determine the resistance between two opposite faces.
2 cm
Q6) A 7.5m aluminum wire is connected in parallel to a 6m long copper wire.
When a 5A current is passed through the combination a 3A current will flow in
the aluminum wire. Determine the diameter of the copper wire, knowing that the
diameter of the Al wire is 1 mm and that 𝜌𝑐𝑢 𝑖𝑠 1.7 𝑥 10−8 Ω . 𝑚 and
𝜌𝑎𝑙 𝑖𝑠 2.8 𝑥 10−8 Ω . 𝑚.
Q7) Calculate the length of a copper wire having a diameter of 1⁄16 𝑖𝑛𝑐ℎ and
resistance of 2Ω. (𝜎𝑐𝑢 = 5.8 𝑥107 𝑆⁄𝑚).
Q8) A 90 cm long aluminum bus bar with rectangular cross section 0.15m wide 1.3
𝑆
cm thick with electric conductivity 𝜎𝑎𝑙 𝑒𝑞𝑢𝑎𝑙𝑠 3.57𝑥108 . Consider the current
𝑚
to flow a long the bus var length, calculate its resistance.
Q9) An 800m long copper cable is made up of 7 wires each having a diameter of
1.7 mm. Calculate the resistance of the cable if resistivity of copper is
1.75𝑥10−8 Ω-m.