Current, Resistance, and DC Circuits

A piece of copper wire 1 millimeter in diameter has a current density of 7 A/m². Calculate the current in the wire.

• 2.20 A

• 5.50 μA

• 7.00 mA

• 22.0 μA

You measure the resistance of a piece of wire as 7.89 mΩ. It has a diameter of 1.2 centimeters and a length of 30 centimeters. Calculate the resistivity of the wire.

• 2.97 mΩ⋅m

• 11.8 mΩ⋅m

• 119 mΩ⋅m

• 24.8 Ω⋅m

Gold has a carrier density of 5.9(10²⁸) m^-3. A current of 20 mA flows through a gold wire with diameter 2.5 millimeters. Calculate the electron drift velocity in the wire.

• 1.08(10^-7) m/s

• 4.32(10^-7) m/s

• 2.70(10^-10) m/s

• 1.08(10⁴⁹) m/s

Aluminum has a carrier density of 6.0(10²⁸) m^-3. Calculate the charge density of aluminum.

• 4.8(10⁶) m^-3

• 9.60(10^-19) m^-3

• 9.60(10⁹) m^-3

• 4.8(10⁹) m^-3

A 220 Ω resistor has a voltage of 3.3 V across it. Calculate the current through the resistor.

• 30 mA

• 15 mA

• 15 A

• 45 mA

A 220 Ω resistor has a voltage of 3.3 V across it. Calculate the power dissipated by the resistor.

• 730 mW

• 495 W

• 49.5 mW

• 3.3 W

Calculate the current through the resistors in the circuit above.

• 9.09 mA

• 3.22 mA

• 7.44 mA

• 6.68 mA

Calculate the current produced by the battery. (HINT: The total current through the circuit.)

• 56.2 mA

• 6.02 mA

• 415 mA

• 5.18 mA

Calculate the current through R7 in the circuit.

• 11.2 mA

• 22.3 mA

• 72.5 mA

• 312 mA