EXAMPLE 31-5 ESTIMATE Phone call time lag. You make a telephone call from New York to a friend in London. Estimate how long it will take the electrical signal generated by your voice to reach London, assuming the signal is (a) carried on a telephone cable under the Atlantic Ocean, and (b) sent via satellite 36,000 km above the ocean. Would this cause a noticeable delay in either case?

(a) A physicist is constructing a solenoid. She has a roll of insulated copper wire and a power supply. She winds a single = 10.0 cm. The resulting solenoid is { = 85.0 cm long, and the = 0.100 cm. Assume the insulation is very thin, and adjacent turns of the wire are in layer of the wire on a tube with a diameter of d. solenoid wire has a diameter of d, wire contact. What power (in W) must be delivered to the solenoid if it is to produce a field of 9.40 mT at its center? (The resistivity of copper is 1.70 × 10¬° Q · m.) W What If? Assume the maximum current the copper wire can safely carry is 24.0 A. (b) What is the maximum magnetic field (in T) in the solenoid? (Enter the magnitude.) (c) What is the maximum power (in W) delivered to the solenoid? W

The inductance of a tuning coil of an am radio is 4mH. Find the capacitance that will give a reception of 12kHz

22) An x-ray tube used for cancer therapy operates at 4.0 MV, with a beam current of 25 mA striking a metal target. Nearly all the power in the beam is transferred to a stream of water flowing through holes drilled in the target. What rate of flow, in kilograms per second, is needed if the rise in temperature (ΔT) of the water is not to exceed 50 C ?