Chapter 6 & 7 Flashcards

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1
Q

An automobile headlight draws a current of 6 amperes, operating on 12 volts . The resistance of the headlight in ohms is

A

2

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2
Q

Suppose current is flowing in a wire from right to left. Which way do the electrons in the wire move?

A

left to right.

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3
Q

A heater is rated at 1200 watts for a 120 volt source. The current in amperes drawn by the heater is

A

10

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4
Q

If a compact fluorescent lightbulb (CFL) breaks, the Environmental Protection Agency (EPA) recommends that hazardous material (HazMet) cleanup procedures be followed. This is because it contains which hazardous material

A

mercury

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5
Q

What is the speed of sound in the air in meters/second inside a furnace where the temperature is 500 degrees Celsius (773 Kelvin)?

A

558.8

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6
Q

You pull on a rope with a certain force, and a wave travels in the rope with a certain velocity. If you exert four times as much force, the velocity of a wave in the rope is now _____ the original velocity.

A

2 times

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7
Q

Why do we use fuses and circuit breakers?

A

to prevent fires.

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8
Q

A light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts. The power consumed by the light bulb in watts is

A

720

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9
Q

Water ripples are produced by making a cork oscillate up and down at a frequency of 5 Hz. The peaks of the ripples are 0.03 meters apart. What is the speed in meters/second of the water ripples?

A

0.15

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10
Q

The term “ultrasound” is applied to waves which have a much greater _____ than sound waves.

A

frequency

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11
Q

What is the usual symbol used to represent an amount of charge?

A

q

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12
Q

You shout at a cliff, and hear your echo in 2 seconds. If the speed of sound in the air is 340 m/s, the distance of the cliff from you in meters is

A

340

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13
Q

The energy in Joules used by a 100 watt light bulb in 1 hour is

A

360000

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14
Q

Which of the following is not an example of real time ultrasound?

A

B-Mode Scanner

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15
Q

the SI unit of electric charge

A

Coulomb

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16
Q

an atom with fewer electrons than protons

A

positive ion

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17
Q

type of current supplied by a battery

A

DC current

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18
Q

employed in appliances like toasters and hair dryers

A

ohmic heating

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19
Q

the SI unit of current

A

Ampere (Amp)

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20
Q

consists of charges flowing back and forth

A

AC current

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21
Q

rate of flow of electric charge

A

electric current

22
Q

used to change AC voltages

A

transformer

23
Q

the energy per unit charge supplied by a battery

A

voltage

24
Q

like charges do this

A

repel

25
Q

a quanity that measures the opposition to the flow of charges

A

resistance

26
Q

In the laboratory, the instructor gives you an unknown resistor to identify. Using a multimeter, you measure a current of 1.5 ma through the resistor, and a voltage of 3.3 V across it. What is the resistance in ohms?

A

2,200

27
Q

A battery operating a large flashlight produces a current of 2 amperes in a light bulb that has a resistance of 4 ohms. The voltage of the battery (in volts) is

A

8

28
Q

An example of a longitudinal wave is a

(A)	sound wave in air.
(B)	wave on a rope.
(C)	water wave.
(D)	ultrasound wave in a human body.
(E)	none of the above.
A

A and D

29
Q

Two charged bodies separated by a distance d exert an electrical force on each other. The charge on one of the bodies is doubled. The electrical forces on each body now

A

double.

30
Q

Real time phased array ultrasound uses the principle of _____________ to sweep an ultrasound beam through a sector of the body.

A

constructive interference.

31
Q

A negative ion is formed when

A

a neutral atom gains an electron.

32
Q

line used to show the path of a wave

A

ray

33
Q

occurs when the amplitudes of two waves add together because they arrive at the same place in phase

A

constructive interference

34
Q

any material through which a wave travels

A

wave medium

35
Q

sound waves used to form images of internal organs

A

ultrasound

36
Q

the maximum displacement of points on a wave

A

amplitude

37
Q

the number of cycles of a wave passing a point per unit time

A

frequency

38
Q

an echo occurs because of ___________ of a sound wave

A

reflection

39
Q

the distance between two successive ‘like’ points on a wave

A

wavelength

40
Q

an ultrasound wave through the body is an example of this type of wave

A

longitudinal wave

41
Q

the distance between peaks of a wave divided by the time for the wave to travel this distance

A

wave velocity

42
Q

If three identical bulbs are connected in parallel across a 12V battery, the voltage across each bulb will be

A

12V.

43
Q

You have two identical ropes stretched with the same force between two different sets of posts. The second rope is twice as long as the first rope. The velocity of a wave in the second rope is _____ the velocity of a wave in the first rope.

A

the same as

44
Q

The wavelength of a wave multiplied by the frequency of the wave is the wave’s

A

velocity

45
Q

What is meant by “like charges?”

A

charges with “like sign,” ie, both positive or both negative.

46
Q

A test tone used on a radio has a frequency of 1,000 Hz. What is the wavelength in meters of this sound in air at normal room temperature? (The speed of sound is 344 meters per second at room temperature.)

A

0.344

47
Q

Two charged bodies separated by a distance d exert an electrical force on each other. The distance d is doubled. The electrical force on each body now

A

decreases by 1/4.

48
Q

Two sound waves traveling through the air have different frequencies. Consequently, they must also have different

A

wavelengths

49
Q

Electrons are

A

negatively charged.

50
Q

A light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts. The resistance of the light bulb in ohms is

A

20

51
Q

If I short out a D cell and draw a current of 7 A for 5 s, how many coulombs of charge move through the circuit?

A

35

52
Q

Sound and Ultrasound are produced when something vibrates, causing nearby molecules to vibrate as a longitudinal wave.
True or False?

A

True