Questions from Modern Physics

Q: An electrical conductor designed to carry large currents has a circular cross

An electrical conductor designed to carry large currents has a circular cross section 2.50 mm in diameter and is 14.0 m long. The resistance between its ends is 0.104 Ω. (a). What is the resistivity...

Q: Two very long, parallel wires carry equal currents in opposite directions

Two very long, parallel wires carry equal currents in opposite directions. (a). Is there any place that their magnetic fields completely cancel? If so, where? If not, why not? (b). How would the ans...

Q: An overhead transmission cable for electrical power is 2000 m long and

An overhead transmission cable for electrical power is 2000 m long and consists of two parallel copper wires, each encased in insulating material. A short circuit has developed somewhere along the len...

Q: On your first day at work as an electrical technician, you

On your first day at work as an electrical technician, you are asked to determine the resistance per meter of a long piece of wire. The company you work for is poorly equipped. You find a battery, a v...

Q: A 2.0-m length of wire is made by

A 2.0-m length of wire is made by welding the end of a 120-cm-long silver wire to the end of an 80-cm-long copper wire. Each piece of wire is 0.60 mm in diameter. The wire is at room temperature, so t...

Q: A student claims that if lightning strikes a metal flagpole, the

A student claims that if lightning strikes a metal flagpole, the force exerted by the earth’s magnetic field on the current in the pole can be large enough to bend it. Typical lightning currents are o...

Q: A 3.00-m length of copper wire at 20

A 3.00-m length of copper wire at 20° C has a 1.20-mlong section with diameter 1.60 mm and a 1.80-m-long section with diameter 0.80 mm. There is a current of 2.5 mA in the 1.60- mm-diameter section....

Q: A heating element made of tungsten wire is connected to a large

A heating element made of tungsten wire is connected to a large battery that has negligible internal resistance. When the heating element reaches 80.0oC, it consumes electrical energy at a rate of 480...

Q: Lightning strikes can involve currents as high as 25,000 A

Lightning strikes can involve currents as high as 25,000 A that last for about 40 ms. If a person is struck by a bolt of lightning with these properties, the current will pass through his body. We sha...

Q: A resistor with resistance R is connected to a battery that has

A resistor with resistance R is connected to a battery that has emf 12.0 V and internal resistance r = 0.40 Ω. For what two values of R will the power dissipated in the resistor be 80.0 W?