PHY 2 E3

440 ohm

6.0-μF capacitor is connected to an ac signal with a frequency of 60 Hz. If the maximum voltage applied to the capacitor is 8.0 V, what is the capacitive reactance? A) 6.0 Ω B) 440 Ω C) 7.5 × 10-6 Ω D) 740 Ω E) 160 Ω

1.54 A

A 120-V rms voltage at 1000 Hz is applied to a resistor and an inductor in series. If the impedance of this circuit is 110 Ω, what is the maximum value of the current? A) 1.54 A B) 1.09 A C) 1.84 A D) 1.04 A E) None of the other answers is correct

36 w

A 120-V rms voltage at 60.0 Hz is applied across a capacitor and a 100-Ω resistor. If the impedance of this circuit is 200 Ω, what is the average power of this circuit?

453 ohm

A 120-V rms voltage is applied across a 6.00-μF capacitor and a 100-Ω resistor. If the frequency of the generator is 60.0 Hz, what is the impedance of this circuit? A)153 Ω B)453 Ω C) 353 Ω D)253 Ω E) 553 Ω

51.5

A 20.0-mH inductor is connected in series with a 100-Ω resistor at 1000 Hz. What is the phase angle of this circuit? A) 90.0° B) 51.5° C) 38.5° D) 0° E) 45°

250 mA

A 45-mH inductor is connected in series with a 60-Ω resistor through a 15-V dc power supply and a switch. If the switch is closed at t = 0 s, what is the current after 7.0 ms? A) 250 mA B) 650 mA C) 550 mA D) 280 mA E) 850 mA

440 ohm

A 6.0-μF capacitor is connected to an ac signal with a frequency of 60 Hz. If the maximum voltage applied to the capacitor is 8.0 V, what is the capacitive reactance? A) 6.0 Ω B) 440 Ω C) 7.5 × 10 -6 Ω D) 740 Ω E) 160 Ω

a=.199, b=8.66

A garage is illuminated by a single light bulb dangling from a wire. If the bulb radiates light uniformaly in all directions, and consumes an average electrical power of 50W, what are a- the average intensity of the light and (Iave=Pave/A) b- the rms values of E and B at a distance 1 m from the bulb (Iave=cB^2/Uo) ( assume that 5% of the electrical power consumed by the bulb is converted to light)

approaches zero

As the frequency of the ac voltage across an inductor approaches zero, the inductive reactance of that coil A) approaches zero. B) approaches one. C) approaches infinity. D) becomes negative.

955 Hz

At what frequency is the reactance of a 20.0-mH inductor equal to 120 Ω? A) 318 Hz B) 637 Hz C) 796 Hz D) 955 Hz E) 1110 Hz

0.16 MHz

At what frequency will the capacitive reactance of a 0.010-μF capacitor be 100 Ω? A) 1.0 kHz B) 16 kHz C) 0.16 MHz D) 0.31 MHz

a= 17V, b= .064A, c= 1.09W

An ac generator with a maximum voltage of 24 V and a frequency of 60 Hz is connected to a resistor with a resistance R= 265 Ω. Find a- the rms voltage and (Vrms= Vmax/radical2) b-the rms current in the circuit (Irms= Vrms/R) c- determine the average power dissipated in the resistor. (Pave=Vrms x Irms)

Horizontal and pointing south

An electromagnetic wave is propagating towards the west. At a certain moment the direction of the magnetic field vector associated with this wave points vertically up. What is the direction of the electric field vector? A) Horizontal and pointing south B) Vertical and pointing down C) Horizontal and pointing north D) Vertical and pointing up E) Horizontal and pointing east

+x

An electromagnetic wave propagates along the +y direction as shown in Figure above. If the E-field at the origin is along the +z direction, what is the direction of the B-field? A) +z B) -z C) +y D) +x E) -x

.31 ms

How long does it take for the current in an RL circuit with R = 150 Ω and L = 67 mH to reach half its final value?

it decreases

In a RLC circuit, a second capacitor is connected in parallel with the capacitor previously in the circuit. What is the effect of this change on the impedance of the circuit? A) It increases. B) It decreases. C) It does not change. D) It increases for frequencies below resonance and decreases for frequencies above resonance. E) It decreases for frequencies below resonance and increases for frequencies above resonance

0

In a pure resistive circuit, the phase angle between current and voltage is A) 0. B) π/2 radians. C) -π/2 radians. D) π radians. E) 3π/4 radians

increase

Consider a capacitor connected across the ac source. As the capacitance is increased, the current through the capacitor will A) increase. B) remain constant. C) decrease

true only if XL is less than or equal to XC

Consider an RLC series circuit. The impedance of the circuit increases if XC increases. A) true only if XL is greater than or equal to XC B) true only if XL is less than or equal to XC C) always true D) never true

.19kHz

Find the frequency at which a 26 μF capacitor has the same reactance as a 26 mH inductor. What is the resonance frequency of an LC circuit made with this inductor and capacitor? w= 1/radical(LC)

6.0 Hz

The capacitive reactance of a 44-μF capacitor in an ac circuit is 6.0 × 102 Ω. What is the frequency of the applied signal? A) 80 Hz B) 17 Hz C) 800 Hz D) 6.0 Hz E) 2.2 Hz

16W

The current through a 50-Ω resistor is I = (0.80 A) sin(240t), where t is measured in seconds. How much power on average is dissipated in the resistor? A) 16 W B) 32 W C) 45 W D) 64 W

500s

The distance between Earth and sun is 1.5 x1011 m How long does it take for light to cover this distance t= d/c

5.7 V

The maximum voltage of an ac signal is 8.0 V. What is the rms value of this voltage? A) 2.8 V B) 5.7 V C) 6.2 V D) 4.0 V E) 16.0 V

345 ohm

The phase angle of a series RL circuit with a 20.0-mH inductor and a certain resistor at 1000 Hz is 20.0°. What is the value of the resistance in this circuit? A) 145 Ω B) 100 Ω C) 245 Ω D) 200 Ω E) 345 Ω

8 A

The primary coil of a transformer has 100 turns and its secondary coil has 400 turns. If the ac current in the secondary coil is 2 A, what is the current in its primary coil? A) 2 A B) 8 A C) 1/2 A D) 1/4 A E) 4 A

1.90x10^-6

The value of the electric field for a certain type of electromagnetic wave is 570 N/C. What is the value of the magnetic field for that wave? A) 2.91 × 10-6 T B) 1.90 × 10-6 T C) 1.10 × 10-6 T D) 1.41 × 10-6 T E) 2.41 × 10 -6 T

3.5 s

In an RL series circuit connected to a dc source and a switch, the inductor gets 40% of its maximum current 1.8 s after the switch is closed at t = 0 s. What is the time constant of this circuit? A) 0.80 s B) 1.5 s C) 2.5 s D) 3.5 s E) 5.5 s

a= .28A, b= .028A

Suppose the capacitance in the figure is 6.25 μF and the rms voltage of the generator is 120V. Find the rms current in the circuit when the frequency of the generator is a. 60 Hz b. 6 Hz eq) Irms=wCVrms

ohms

what are the units of capacitive reactance

ohms

what are the units of inductive reactance

webs per ampere (1 H or Wb/A)

what are the units of self inductance

6.0x10^5

What is the distance traveled by a beam of light in a time of 2.0 ms? A) 6.0 × 10 5 m B) 0.66 × 10 5 m C) 90 m D) 70 m E) 60 m

170 V

What is the peak voltage in an ac circuit where the rms voltage is 120 V? A) 84.8 V B) 120 V C) 170 V D) 240 V

180

What is the phase angle between the voltages of the inductor and capacitor in a RLC series circuit? • A) zero • B) 45° • C) 90° • D) 180° • E) 270°

7.5 ohm

What is the reactance of a 20-mH inductor at a frequency of 60 Hz? A) 7.5 Ω B) 0.13 Ω C) 1.2 Ω D) 1.2 mΩ E) 7.5 mΩ

31 uA

What is the rms current through a 0.0010-μF capacitor at 1000 Hz and 5.0 V? A) 5.4 μA B) 31 μA C) 3.1 mA D) 10 mA

1/radical(EoUo)

Which of the following expressions is the correct representation for the speed of light? A) radical (EoUo) B) radical (Eo/Uo) C) radical (Uo/Eo) D) 1/radical(EoUo) E) 3/ radical(EoUo)

ohm

Which of the following is the correct expression for the SI units of the capacitive reactance? • A) Ω∙S • B) Ω/S • C) J∙A/s • D) Ω • E) J/m

sound waves

Which one of the following is not an electromagnetic wave? • A)UV • B)infrared • C) radiowaves • D) sound waves • E) gammarays

c= f x lamda

Which one of the following is the correct relationship between the speed of a wave (v), frequency of the wave (f), and its wavelength (λ)? • A) c = 2 λ • B) c =2f • C) c = λ / f • D) c = f λ • E) c = f / λ

a= 499, b= 258, c= 0

Vertically polarized light with intensity of 515 W/m2 passes through a polarizer at angle θ to the vertical. Find the transmitted intensity of the light for: • a- θ=10 • b- θ= 45 • c- θ= 90

reduced to one-half the original value

) In an RLC ac circuit, the values of the inductance and capacitance are both doubled. As a result of this change, the resonance frequency of the circuit is A) the same as before. B) reduced to one-half the original value. C) reduced to one-fourth the original value. D) twice the original value. E) four times the original value.

less brightly

- Shown in the sketch are two circuits with identical ac generators and lightbulbs. Circut 2 differ from circuit 1 by addition of a capacitor in series with the light. Does the light bulb in 2 shine a- more brightly b- less brightly c- the same as that in circuit 1

a= .112, b= 25.2V, C= 16V

A 0.380 H inductor and 225 ohm resistor are connected in series to an ac generator with an rms voltage of 30 V and a frequency of 60 Hz. Find thr rms values of a- the current in the circuit (Z= radical(R^2+(wL)^2)) --> (Irms= Vrms/Z) b- the voltage across the resistor, ( Vrms,r= Irms x R) c-the voltage across the inductor ( Vrms,l= Irms x Xl)

442 Hz

A Doppler weather radar operates at a frequency of 3.40 GHz. The wave from this radar system reflects from an approaching weather system moving with a speed of 39.0 m/s. What is the difference in frequency between the outgoing and returning waves? A) 442 Hz B) 351 Hz C) 419 Hz D) 322 Hz E) 670 Hz

6.21 Hz

A car is approaching a radio station at a speed of 25.0 m/s. If the radio station broadcasts at a frequency of 74.5 MHz, what change in frequency does the driver observe? A) 98.3 Hz B) 6.21 Hz C) 726 Hz D) 67.0 Hz E) 64.5 Hz

a= 54ohm, b=340W

A certain RC circuit has an ac generator with an rms voltage of 240V. The rms current in the ciruit is 2.5 A, and it leads the voltage by 56 degree. Find a- the value of the resistance R (z= Vrms/Irms --> R=Zcostheta) b- the average power consumed by the circuit. (Pave= Irms x Vrms)

0

A polarizer is oriented at an angle θ to the vertical. If the vertically polarized beam of light of intensity 200 W/ m2 passes through the polarizer, find the transmitted intensity of light for an angle of 90.0°. A) 0 W/m2 B) 50.0 W/m2 C) 400 W/m2 D) 100 W/m2 E) 200 W/m2

177

A polarizer is oriented at an angle θ to the vertical. If the vertically polarized beam of light of intensity 200 W/m2 passes through the polarizer, what is the transmitted intensity of light for an angle of 20.0°? A) 35.0 W/m2 B) 44.4 W/m2 C) 177 W/m2 D) 23.0 W/m2 E) 200 W/m2

leads the voltage by 90

A pure capacitor is connected to an ac power supply. In this circuit, the current A) leads the voltage by 90°. B) lags the voltage by 90°. C) lags the voltage by 180°. D) is in phase with the voltage. E) None of the given answers are correct.

lags the voltage by 90

A pure inductor is connected to an ac power supply. In this circuit, the current A) leads the voltage by 90°. B) is in phase with the voltage. C) lags the voltage by 45°. D) lags the voltage by 90°. E) leads the voltage by 45°

20x10^6

A radio station broadcasts at a frequency of 80 MHz. How far will this signal travel in 67 ms? A) 60 × 10 6 m B) 67 m C) 40 × 106 m D) 80 m E) 20 × 106 m

zero

A resistor and a capacitor are connected in series to an ideal battery of constant terminal voltage. At the moment contact is made with the battery, the voltage across the capacitor is A) greater than the battery's terminal voltage. B) equal to the battery's terminal voltage. C) less than the battery's terminal voltage, but greater than zero. D) zero.

is in phase with the voltage

A resistor is connected to an AC power supply. On this circuit, the current • A) leads the voltage by 90°. • B) lags the voltage by 90°. • C) is in phase with the voltage. • D) leads the voltage by 45°. • E) lags the voltage by 45°

It decreases by a factor of four

A simple ac circuit consists of an inductor connected across the terminals of an ac power source. If the frequency of the ac source is decreased by a factor of four, what happens to the reactance of the inductor? A) It decreases by a factor of four. B) It decreases by a factor of eight. C) It increases by a factor of two. D) It increases by a factor of four. E) It increases by a factor of eight

769 ohm

A total impedance of an RC circuit with a capacitance of 40.0 μF is 800 Ω. If the frequency of the applied ac voltage is 18.0 Hz, what is the resistance of the circuit? A) 569 Ω B) 669 Ω C) 769 Ω D) 869 Ω E) 800 Ω

a= 226ohm, b= .531A

Ac generator with a frequency of 60 HZ and an rms voltage of 120 v is connected in series with a 175 ohm resistor, a 90 mH inductor, and 15 μF capacitor. a- Calculate the impedance (Z= radical(R^2+(wL- 1/wC)^2) b-rms current for this circuit. (Irms= Vrms/Z

7.96 Hz

An FM radio station broadcasts at a frequency of 91.5 MHz. If you drive your car toward the station at 26.1 m/s. what change in frequency do you observe? f= fo (1+ u/c)

in phase with the current

An RLC circuit is driven at its resonance frequency.Is its voltage a- ahead of b- behind c- in phase with the current

transverse

Electromagnetic waves are A) transverse. B) longitudinal. C) longitudinal and transverse. D) None of the other answers given is correct.

1010

If the radiation from the Sun reaching above atmosphere of Earth is at the rate of 1350 W/m2, what is the maximum value of the electric field associated with this wave? A) 675.0 V/m B) 1604 V/m C) 1400 V/m D) 1350 V/m E) 1010 V/m

only case 2

If unpolarized light is incident from the left, in which case will some light get through? a) only case 1 b) only case 2 c) only case 3 d) cases 1 and 3 e) all three cases

I0/2

If unpolarized light of intensity I0 passes through an ideal polarizer, what is the intensity of the emerging light? A) I0 B) I0/2 C) I0/4 D) I0/ radical(2) E) I0/16

3.2 uF

In the circuit shown in the figure, the 60-Hz ac source has a voltage amplitude of 120 V, the capacitive reactance is 820 ohm, the inductive reactance is 330 ohm, and the resistance is 550 ohm. What is the capacitance C of the capacitor? A) 3.2 µF B) 6.3 µF C) 9.4 µF D) 13 µF E) 20 µF

XC equals X

Resonance in a series RLC circuit occurs when • A) XL is greater than XC. • B) XC is greater than XL. • C) (XL - XC) is equal to R2. • D) (XL - XC)2 is equal to R2. • E) XC equals XL.

less brightly

Shown in the sketch are two circuits with identical ac generators and lightbulbs. Circut 2 differ from circuit 1 by addition of an inductor in series with the light. Does the light bulb in 2 shine a- more brightly b- less brightly c- the same as that in circuit 1

3.07x10^-2

The frequency of a microwave signal is 9.76 GHz. What is its wavelength in meters? A) 3.07 × 10 -2 m B) 2.07 × 10-2 m C) 1.07 × 10 -2 m D) 5.07 × 10 -2 m E) 4.07 × 10 -2 m

radio waves, microwaves, infrared, visible, UV, X-rays, gamma rays

Which one of the following is the correct order of the electromagnetic spectrum from low to high frequencies? A) radio waves, infrared, microwaves, UV, visible, X-rays, gamma rays B) radio waves, UV, X-rays, microwaves, infrared, visible, gamma rays C) radio waves, microwaves, infrared, visible, UV, X-rays, gamma rays D) radio waves, microwaves, visible, X-rays, infrared, UV, gamma rays E) radio waves, infrared, X-rays, microwaves, UV, visible, gamma rays

All of the answers are correct

Which one of the following is the correct unit for the time constant of an RL circuit? A) H/Ω B) (V∙s)/(A∙Ω) C) s D) All of the answers are correct. E) None of the answers is correct