Exam 27: Currents and Ohms Law

The current through a copper wire (resistivity of 1.7 $\times$ 10^-8 $\Omega$ .m that has a radius of 1.5 mm and length of 100.0 m when a 1.5-V potential is applied across the ends of the wire is

The resistivity of a conductor depends on the collision time by an equation of the form

Two resistors, 20 $\Omega$ and 30 $\Omega$ , are connected in parallel. A third resistor, 24 $\Omega$ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 30- $\Omega$ resistor is

A current of 15 mA is passing through a wire. The time it will take for 15 C of charge to pass through a given point in the wire is

Two resistors are connected in series, and the value of R₁ is twice the value of R₂. The resistor with the larger potential across it is

The electric field in a uniform wire is related to the potential across the wire, $\Delta$ V, and the length of the wire, $l$ , by

A wire whose circular cross section is not uniform carries a current I. Relative to the larger region, the drift velocity in the narrower region is

A wire's diameter decreases linearly from d_i to d_f = d_i/2. If the wire has a current of I at the end whose diameter is d_i, then the current at the end whose diameter is d_i/2

If the average collision time of an electron increases by a factor of 2, the resistivity of the material will

A 75-m length of copper wire whose resistivity is 1.7 $\times$ 10^-8 $\Omega$ . m has a resistance of 1.6 $\Omega$ . The diameter of the wire is