Can a 2.5-mm-diameter copper wire have the same resistance as a tungsten wire of the same length? Give numerical details.

What is the resistance of a 3.5-m length of copper wire 1.5 mm in diameter?

A bird sits on a high-voltage power line with its feet 2.0 cm apart. The wire is made from aluminum, is 2.0 cm in diameter, and carries a current of 150 A. What is the potential difference between the bird's feet?

Which draws more current, a 100-W lightbulb or a 75-W bulb? Which has the higher resistance?

What is the diameter of a 1.00-m length of tungsten wire whose resistance is $0.32 \Omega ?$

A 12-V battery causes a current of 0.60 A through a resistor. How many joules of energy does the battery lose in a minute?

Two children are sitting on opposite ends of a uniform seesaw of negligible mass. (a) Can the seesaw be balanced if the masses of the children are different? How? (b) If a 35-kg child is 2.0 m from the pivot point (or fulcrum), how far from the pivot point will her 30-kg playmate have to sit on the other side for the seesaw to be in equilibrium?

Two children, with masses $35 \mathrm{~kg}$ and $40 \mathrm{~kg}$, sit at opposite ends of a 3.4-m-long seesaw with mass $25 \mathrm{~kg}$, with the fulcrum at its midpoint. With the seesaw horizontal, find (a) the net torque on the seesaw.

Suppose two children are using a uniform seesaw that is 3.00 m long and has its center of mass over the pivot. The first child has a mass of 30.0 kg and sits 1.40 m from the pivot. (a) Calculate where the second 18.0 kg child must sit to balance the seesaw. (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?

A 12-V battery causes a current of 0.60 A through a resistor. What is its resistance.

Explain why lightbulbs almost always burn out just as they are turned on and not after they have been on for some time.

An electric device draws 6.50 A at 240 V. If the resistance of the device were reduced by 15%, what current would be drawn at 240 V?

In a television picture tube, electrons are accelerated by thousands of volts through a vacuum. If a television set were laid on its back, would electrons be able to move upward against the force of gravity? What potential difference, acting over a distance of 3.0 cm, would be needed to balance the downward force of gravity so that an electron would remain stationary? Assume that the electric field is uniform.

An electric device draws 6.50 A at 240 V. If the voltage drops by 15 %, what will be the current, assuming nothing else changes?