Solved: The peak current through a resistor is 2.0 A. What

Identical resistors are connected to separate 12 V AC sources. One source operates at 60 Hz, the other at 120 Hz. In which circuit, if either, does the resistor dissipate the greater average power?

Consider the three circuits in Figure Q26.2. Rank in order, from largest to smallest, the average total powers P1 to P3 dissipated by all the resistors in each circuit. Explain.

Most battery-powered devices won' t work if you put the battery in backward. But for a device that you plug in, you can often reverse the orientation of the plug with no problem. Explain the difference.

If a lightbulb is connected to a 120 V, 60 Hz electric o utlet, how many times a second does the bulb reach peak brightness? (This flicker is too fast for you to see.)

A soldering gun contains a transformer that lowers the 120 V from an outlet to a few volts. It's possible to have a current of 150 A in the tip of the soldering iron even though the outlet has a c ircuit breaker that permits no more than 15 A. Explain how th is is possible.

A 12 V DC power supply is connected to the primary coil of a transformer. The primary coil has I 00 turns and the secondary coi I has 200. What is the rms voltage across the secondary?

Figure Q26.7 shows three wires wrapped around an iron core. The fig- A ure shows the number of turns and the direction of each of the windings. At one particular instant, VA - V0 = 20 V. At that same instant, what is Ve - V0 ?

Women usually have higher resistance of their arms and legs than men. Why might you expect to see this variation in resistance?

If you work out enough to visibly increase the diameter of your biceps, will this increase or decrease your susceptibility to electric shock? Explain.

A circuit breaker won't keep you from getting a shock; a GFI will. Explain why this is so.

New homes are required to have GFl-protected outlets in bathBIO rooms, kitchens, and any outdoor locations. Why is GFI protection required in these locations but not, say, in bedrooms?

The peak current through a resistor is 2.0 A. What is the peak current if a. The resistance R is doubled? b. The peak emf 0 is doubled? c. The frequency f is doubled?

The peak current through a capacitor is 2.0 A. What is the peak current if a. The peak emf 0 is doubled? b. The capacitance C is doubled? c. The frequency f is doubled?

Consider the four circuits in Figure Q26. 14. Rank in order, from largest lo s1nallest, the capacitive reactances (Xc)1 to (Xck Explain.

An inductor is plugged into a 120 V, 60 Hz wall outlet in the U.S. Would the peak current be larger, smaller, or unchanged if this inductor were plugged into a wall outlet in a country where the voltage is 120 Vat 50 Hz? Explain.

An inductive loop buried in a roadway detects the presence of cars above it, as described in the chapter. If the loop is connected to an AC supply, will the current increase or decrease when a car drives above the loop?

"Figure Q26. l 7 shows two inductors and the potential di fference across them at time t = 0 s. a. Can you tell which of these inductors has the larger current flowing through it at I = 0 s? If so, which one? If not, why not? b. Can you tell through which inductor the cmTent is changing more rapidly at t = 0 s? If so, which one? If not, why not?"

"The peak current passing through an inductor is 2 .0 A. What is the peak current if a. The peak emf 0 is doubled? b. The inductance l is doubled? c. The frequency f is doubled?"

Consider the four circuits in Figure Q26. l 9. Rank in order, from largest to smallest, the inductive reactances (XL)i to (XLk Explain.

The tuning circuit in a radio uses an RLC circuit. Will adjusting the resistance have any effect on the resonance frequency?

The resonance frequency of a driven RLC circuit is 1000 Hz. What is the resonance frequency if a. The resistance R is doubled? b. The inductance l is doubled? c. The capacitance C is doubled? d. The peak emf E0 is doubled?

Consider the four circuits in Figure Q26.22. They all have the same resonance frequency Jo and are driven by the same emf. Rank in order, from largest to smallest, the maximum currents Umax)J to Umaxk Explain.

A transformer has 1000 turns in the primary coil and 100 turns in the secondary coil. If the primary coil is connected to a 120 V outlet and draws 0.050 A, what are the voltage and current of the secondary coil? A. 1200 V, 0.0050 A B. 1200 V, 0.50 A C. 12 V, 0 .0050 A D. 12 V, 0.50 A

An inductor is connected to an AC generator. As the generator' s frequency is increased, the current in the ind uctor A. Increases. B. Decreases. C. Does not change.

A capaci tor is connected to an AC generator. As the generator' s frequency is increased, the current in the capacitor A. Increases. B. Decreases. C. Does not change.

An AC source is connected to a series combination of a lightbulb and a variable inductor. If the inductance is increased, the bulb's brightness A. Increases. B. Decreases. C. Does not change.

An AC source is connected to a series combination of a lightbulb and a variable capacitor. If the capaci tance is increased, the bulb's brightness A. Increases. B. Decreases. C. Does not change.

T he circuit shown in Figure Q26.28 has a resonance frequency of 15 kHz. What is the value of l ? A. 1.6 ,H B. 2.4 ,H C. 5.2 ,H D. 18,H V E. 59 ,H

At resonance, a driven RLC circuit has Ve = 5.0 V, VR = 8.0 V, and VL = 5.0 V. What is the peak voltage across the entire circuit? A. 18V B. JO Y c. 8.0 v D. 5.0V E. 3.0V

A driven RLC circuit has Ve = 5.0 V, VR = 7.0 V, and VL = 9.0 V. The driving frequency is A. Higher than the resonance frequency. B. Equal to the resonance frequency. C. Lower than the resonance frequency.

Would it be possi ble for a person to safely hang from this wire? Assume that the hands are 15 cm apart, and assume a skin resistance of 2200 n.

A 0.30 ,f capacitor is connected across an AC generator that produces a peak voltage of 10.0 V. What is the peak current through the capacitor if the emf frequency is (a) I 00 Hz? (b) 100 kHz?

20 ,f capacitor is connected across an AC generator that produces a peak voltage of 6.0 V. The peak current is 0.20 A. What is the oscillation frequency in Hz?

The peak current through a capacitor is I 0.0 mA. What is the current if a. The emf frequency is doubled? b. The emf peak voltage is doubled (at the original frequency)? c. The frequency is halved and, at the same time, the emf is doubled?

A 20 nF capacitor is connected across an AC generator that produces a peak voltage of 5.0 V. a. At what frequency f is the peak current 50 mA? b. What is the instantaneous value of the emf at the instant when ic = le?

A capacitor is connected to a 15 kHz osci llator that produces an rms voltage of 6.0 V. The peak current is 65 mA. What is the value of the capacitance C?

The peak current through a capacitor is 8.0 mA when connected to an AC source with a peak voltage of 1.0 V . What is the capacitive reactance of the capacitor?

A 20 mH inductor is connected across an AC gene rator that produces a peak voltage of 10.0 V. What is the peak current through the inductor if the emf frequency is (a) I 00 Hz? (b) 100 kHz?

The peak c urrent through an inductor is I 0.0 mA. What is the current if a. The emf frequency is doubled? b. The emf peak voltage is doubled (at the original frequency)? c. The frequency is halved and, at the same time, the emf is doubled?

A 500 ,H inductor is connected across an AC generator that produces a peak voltage of 5.0 V. a. At what freq uency f is the peak current 50 mA? b. What is the instantaneous value of the emf at the instant when iL = IL?

A 500 ,H inductor is connected across an AC generator that produces a peak voltage of 5.0 V. a. At what freq uency f is the peak current 50 mA? b. What is the instantaneous value of the emf at the instant when iL = IL?

An inductor is connected to a 15 kHz oscillator that produces an rms voltage of 6.0 V. The peak current is 65 mA. What is the value of the inductance L?

The peak current through an inductor is 12.5 mA when connected to an AC source with a peak voltage of 1.0 V. What is the inductive reactance of the inductor?

A 2.0 mH inductor is connected in parallel with a variable capacitor. The capacitor can be varied from 100 pf to 200 pf. What is the range of oscillation frequencies for th is circuit?

An FM radio station broadcasts at a frequency of 100 MHz. What inductance should be paired with a 10 pf capacitor to build a receiver circuit for this stat ion?

The inductor in the RLC tuning circuit of an AM radio has a value of 350 mH. What should be the value of the variable capacitor in the circuit to tune the radio to 740 kHz?

At what frequency f do a 1.0 ,f capacitor and a 1.0 ,H inductor have the same reactance? What is the value of the reactance at this frequency?

What capacitor in series with a 100 n resistor and a 20 mH inductor will give a resonance frequency of I 000 Hz?

What inductor in series with a I 00 n resistor and a 2.5 ,f capacitor will give a resonance frequency of I 000 Hz?

A series RLC circuit has a 200 kHz resonance frequency. What is the resonance frequency if the capacitor value is doubled and the inductor value is halved?

An RLC circuit with a 10 F capacitor is connected to a variable-frequency power supply with an rms output voltage of 6.0 V. The rms cun-ent in the circuit as a function of the driving frequency appears as in Figure P26.5 l. What are the values of the resistor and the inductor?

A series RlC c ircuit consists of a 280 fl resistor, a 25 H inductor, and an 18 F capacitor. What is the rms c urrent if the emf is supplied by a standard 120 V, 60 Hz wall outlet

Electric outlets in England are 230 V. Alice brings her electric kettle from England, where it draws 13 A, and wants to use it in the United States. She uses a step-up transformer to increase the 120 V outlet voltage to 230 V, then plugs her kettle into the secondary. What is the current in the primary in the few seconds before the 15 A circuit breaker trips?

The voltage-to-current ratio in the primary coil of a transformer can be thought of as the transformer's effective resistance. A step-down transformer converts 120 V at the primary to 24 V at the secondary, which is connected to a load of resistance 8.0 fl. What is the effective resistance of this transformer when connected to this load? Hint: Resistance is defined as the ratio of two circuit quantities.

A 15-km-long, 230 kV aluminum transmission line delivers 34 MW to a city. If we assume a solid cylindrical cable, what minimum diameter is needed if the voltage decrease along this run is to be no more than 1.0% of the transmission voltage? The resistivity of aluminum is 2.7 X 10-8 fl m.

The voltage across a 60 F capacitor is described by the equation vc = (18 V)cos(200t), where I is in seconds. a. What is the voltage across the capac itor at I = 0.010 s? b. What is the capac itive reactance? c. What is the peak current?

The voltage across a 75 H inductor is described by the equation vL = (25 V)cos(60t), where t is in seconds. a. What is the voltage across the inductor at t = 0.10 s? b. What is the inductive reactance? c. What is the peak current?

An e lectronics hobbyist is building a radio set to receive the AM band, with frequencies from 520 kHz to 1700 kHz. The antenna, which also serves as the inductor in an LC circuit, has an inductance of 230 H. She needs to add a variable capacitor whose capacitance she can adjust to tune the radio. What is the minimum capacitance the capacitor must have? The maximum value?

For the circuit of Figure P26.59, a. What is the resonance frequency? b. At resonance, what is the peak current through the circuit?

For the circuit of Figure P26.60, a. What is the resonance frequency? b. At resonance, what is the peak current through the circuit?

If the frequency is doubled to 80 kHz and the current is kept the same, what will be the peak out-of-phase voltage? A. 0.32V B. 0.16V C. 0.080 V D. 0.040 V

What is the approximate capacitance of the cell membrane? A. 20 X 10- 11 F B. lO X 10- 11 F C. 5.0 x 10-11 F D. 2.5 x 10- 11 F

What is the approximate capacitance of the cell membrane? A. 20 X 10- 11 F B. lO X 10- 11 F C. 5.0 x 10-11 F D. 2.5 x 10- 11 F

If the capacitance of a cell membrane is measured to be 6.0 x 10- 11 F, what is the area? A. 6.0 X 10- 13 m2 B. 6.0 X 10-11 m2 C. 6.0 X 10-9 m2 D. 6.0 X 10-7 m2

If the investigator applies a 1.0 A peak current at 40 kHz to a cell with twice the membrane area of the cell noted in the passage, what will be the peak out-of-phase voltage? A. 0.32 V B. 0.16 V C. 0.080V D. 0.040 V

The 12 V rating of the bulb refers to the nns voltage. What is the peak voltage across the bulb? A. 8.SV B. 12V c. 17 v D. 24 V

Suppose the transformer in the base of the lamp has SOO turns of wire on its primary coil. How many turns are on the secondary coil? A. SO B. 160 C. SOO D. SOOO

How much current is drawn by the lamp at the outlet? That is, what is the rms current in the primary? A. 0.42 A B. 1.3 A C. 4.2 A D. 13A

What wi ll be the voltage across the bulb if the lamp's powe r cord is accidentally plugged into a 240 V, 60 Hz outlet? A. 2V B. 24 V c. 36 v D. 48V