A 9.0 V battery is connected to three resistors as shown in the figure below with R₁ = 502, R₂ 100 , and R3 = 75 Q = a. Draw the equivalent simplified circuit diagram. b. Determine the current drawn from the battery. C. With the value of current from the battery, find the voltage across and current through each resistor. Enter the values in a table 9.0 V 50 Ω 100 Ω www ww 75 02

You have a faculty position at a community college and are teaching a class in automotive technology. You are deep in a discussion of using jumper cables to start a car with a dead battery from a car with a fresh battery. You have drawn the circuit diagram in Figure P27.16 to explain the process. The battery on the left is the live battery in the correctly functioning car, with emf and internal resistance RL, where the L subscript refers to live. Its terminals are connected directly across those of the dead battery, in the middle of the diagram, with emf and internal resistance RD, where the D subscript refers to dead. Then, the starter in the car with the dead battery is activated by closing the ignition switch, allowing the car to start. The resistance of the starter is RS. A student raises his hand and asks, So is the dead battery being charged while the starter is operating? How do you respond? Figure P27.16

You have been called in as an expert witness in a civil case. The case involves a dispute between neighbors. The plaintiff neighbor is complaining about a buzzing noise during the night that prevents the plaintiff from sleeping. He claims that the buzzing is coming from a light fixture on the defendants porch ceiling. The defendant likes to do installations and repairs himself and has done a sloppy job of installing the light fixture. The fixture hangs vertically from a single wire that is attached through the porch ceiling and down the wall to one connector in a nearby electrical outlet. The second wire is hung horizontally with strings at the level of the light and then runs down the wall to the other connector in the outlet. The defendant leaves the light on all night long for security. Recalling his high school physics, the plaintiff states that the combination of the 60-Hz household voltage and the magnetic field of the Earth results in an oscillating driving force on the single wire from which the light fixture hangs vertically. This, in turn, sets up a standing wave in the wire, and that is the cause of the buzz. You have been hired by the defense attorney. Upon hearing the details of the case, you obtain permission from the defendant and make measurements. The mass of the light fixture is 17.5 kg. The vertical wire from which it hangs is 0.150 m long and has a mass of 0.030 kg. Is the plaintiff correct that the magnetic field of the Earth is causing the buzzing of the wire? Ignore any effect of the second wire.

You are part of a team working in a machine parts mechanics shop. An important customer has asked your company to provide springs with a very precise force constant k. You dense the electrical circuit shown in Figure P25.45 to measure the spring constant of each of the springs to be provided to the customer. The circuit consists of two identical, parallel metal plates free to move, other than being connected to identical metal springs, a switch, and a battery with terminal voltage V. With the switch open, the plates are uncharged, are separated by a distance d, and have a capacitance C. When the switch is closed, the plates become charged and attract each other. The distance between the plates changes by a factor f, after which the plates are in equilibrium between the spring forces and the attractive electric force between the plates. To keep the plates from going into oscillations, you hold each plate with insulating gloves as the switch is closed and apply a force on the plates that allows them to move together at a slow constant speed until they are at the equilibrium separation, at which point you can release the plates. You determine an expression for the spring constant in terms of C, d, V, and f. Figure P25.45 Problems 45 and 50.

You have a faculty position at a community college and are m (caching a class in automotive technology. You are deep in a discussion of using jumper cables to start a car with a dead battery from a car with a fresh battery. You have drawn the circuit diagram in Figure P27.16 to explain the process. The battery on the left is the live batten- in the correctly functioning car, with emf and internal resistance RL where the L. subscript refers to live. Its terminals are connected directly across those of the dead battery, in the middle of the diagram, with emf and internal resistance RD where the D subscript refers to "dead Then, the starter in the car with the dead battery is activated by closing the ignition switch, allowing the car to start. The resistance of the starter is Rs. A student raises his hand and asks, So is the dead battery being charged while the starter is operating? How do you respond?

If you were 10 design an electric healer using Nichrome wire as the healing element, what parameters of the wire could you vary to meet a specific power output such as 1 000 W?

What would be the maximum cost of a CFL such that the total cost (investment plus operating) would be the same for both CFL and incandescent 60-W bulbs? Assume the cost of the incandescent bulb is 25 cents and that electricity costs 10 cents/kWh, Calculate the cost for 1000 hours, as in the cost effectiveness of CFL example.

Construct Your Own Problem Consider a person working in an environment where electric currents might pass through her body. Construct a problem in which you calculate the resistance of insulation needed to protect the person from harm. Among the things to be considered are the voltage to which the person might be exposed, likely body resistance (dry, wet, ...), and acceptable currents (safe but sensed, safe and unfelt, ...).

Integrated Concepts A battery-operated car utilizes a 12.0 V system. Find the charge the batteries must be able to move in order to accelerate the 750 kg car from rest to 25.0 m/s. make it climb a 2.00 102 m high hill, and then cause it to travel at a constant 25.0 m/s by exerting a 5.00 102 N force for an hour.

Name two applications for superconductivity listed in this section and explain how superconductivity is used in the application. Can you think of a use for superconductivity that is not listed?