Chapter 6&7

The speed of light in a transparent plastic whose index of refraction is 1.5 is

2 x 10^8 m/s

The primary coil of a transformer has 200 turns and it's secondary coil has 50 turns, and the current in the secondary coil is 40A. When a 12 V alternating current is applied to the primary coil of the transformer, the secondary voltage will be

3 V

The voltage needed to produce a current of 8 A in a resistance of 12 ohms is

96

The wavelength of a wave measures from

Crest to crest

Relative to its object, a real image formed by a lens is always

Larger

You are looking at the bottom of a lake 1.2 m deep from a boat. To you the lake seems to be

Less than 1.2 m deep

A compass needle tends to

Line up parallel to a magnetic field

Relative to the focal length of a wide-angle camera lens, the focal length of a telephoto lens is

Longer

electric charge

Occurs only in separate parcels of +\- 1.6 * 10^-19 C

A current carrying loop in a magnetic field always tends to turn until the plane of the loop is

Parallel to the field

Which one of the following effects does not occur in all types of wave?

Polarization

The image the lens of the eye forms on the retina is

Real and inverted

Light of which of the following colors has the longest wavelength

Red

An example of a purely longitudinal wave is a

Sound wave

Of the following kinds you of waves, those that cannot be polarized are

Sound waves

Relative to the electric force between two protons, the gravitational force between them is

Weaker

An object has a positive electric charge whenever

it has a deficiency of electrons

The amplitude of a sound wave determines its

loudness

The watt, the unit of power, is equal to the

voltampere

An example of a wave that is partly longitudinal and partly transverse is a

water wave

The primary coil of a transformer has 200 turns and it's secondary coil has 40 turns. If the current in the secondary coil is 25 A, the current in the primary coil is

5A

Three 12 V batteries cannot be connected to give a voltage for the set of

6 v

In a transverse wave, the individual particles of the medium move

Perpendicular to the direction of travel

A molecule that has lost an electron becomes a

Positive ion

Which of the following statements is not true?

A proton in an atom circulates around its nucleus

Coulomb's formula gives the force between two charges in free space. The value of K

Is the same under all circumstances

The greater the decibel (dB) level of a sound wave, the

Louder it is

When a magnetized iron bar is strongly heated, its magnetic field

becomes weaker

A magnet attracts

some substances and repels others

The nucleus of an atom

contains most of the atom's mass

A kilowatt-hour is a unit of

energy

When a sound wave goes from air into water, the quantity that remains unchanged is its

frequency

The current with which a transformer is used

must be ac

Two waves meet at a time when one has the instantaneous amplitude A and the other has the instantaneous amplitude B. Their combined amplitude at this time is

A + B

A boat at anchor is rocked by waves whose crests are 50 m apart and whose speed is 10 m/s. These waves reach the boat once every

5s

An electric iron draws a current of 15 A when connected to a 120-V power source. Its resistance is

8 ohms

Sound waves of frequency 300 Hz have a wavelength relative to sound waves in the same medium frequency 600 Hz that is

Twice as great

Two 60 watt light bulbs are connected in series across a 120 V power line. The current in each bulb is

0.5 A

A 80-dB sound carries more energy than a 40-dB sound by a factor of

10,000

Ocean waves with a period is 10s are found to have a length of 120m. Their speed is

12 m/s

The musical note A has a frequency of 440 Hz and it's wavelength in seawater is 3.5m. The speed of sound in seawater is

1540 m/s

Radio amateurs are permitted to communicate on the "10 meter band ". What frequency of radio waves corresponds to wavelength of 10 m? The speed of radio waves is 3x10^8 m/s

3.0 x 10^7 Hz

A transformer used to reduce 240 V ac to 120 V ac has an input current of 15 A. It's output current is

30 A

A medal in a plastic cube whose index of refraction is 1.5 appears to be 20 mm below the upper surface of the cube. The depth of the medal is actually

30 mm

The resistance of a 30

4.8 ohms

The electric energy stored in a 6v battery rated at 20 AH

432 kj

Relative to the radio signals sent out by a spacecraft headed away from the earth, the signals that are received on the earth have

A lower frequency

A changing electric field gives rise to

A magnetic field

When a current passes through a resistance, the electric energy that is lost

Becomes heat

Light of which of the following colors is scattered most in the atmosphere?

Blue

The Swedish flag is blue and yellow. When viewed with blue light it appears

Blue and black

Two charges, one positive and the other negative, are initially 2 cm apart and are then pulled away from each other until they are 8 cm apart. The force between them is now smaller by a factor of

C. 16

Two charges repel each other with a force of 10-6 N when they are 10 cm apart. When they are brought closer together until they are 2 cm apart, the force between them becomes

D. 2.5 × 10-5 N.

A current carrying wire is in a magnetic field with the direction of the current parallel to that of the field

D. The wire has no tendency to move or to turn.

The bending of waves around the edge of an obstacle in their path is an example of

Diffraction

A current is flowing south along a power line. Neglecting the earths field, the direction of the magnetic field under the power line is

East

The conventional unit of battery capacity is the ampere-hour, which is actually a unit of

Electric charge

Which of the following is not a property of an electromagnetic wave?

Electric charge

Atoms and molecules are normally

Electrically neutral

When waves go from one place to another, they carry

Energy

A frequency that is not an overtone of the fundamental frequency F is

F/2

A converging lens of focal length f produces a real image of a real object when the object is

Farther than f from the lens

The property of light waves that leads to the phenomenon of color is

Frequency

A sound wave whose frequency is 50 HZ

Has a relatively long wavelength

A wave of amplitude A interferes with another wave of identical amplitude (A), frequency, wavelength, and phase. The resulting wave

Has an amplitude of 2A

Ohm's Law

Holds only for metals

When the voltage across a certain resistance is the V, the power delivered is P. If the voltage is halved to V/2, the power delivered becomes

P/4

Which of the following is not true?

Protons and electrons have equal masses

Dispersion is the term used to describe the

Splitting of white light into its component colors in refraction

Sound waves of frequency 300 Hz have a speed relative to sound waves in the same medium frequency 600 Hz that is

The same

Direct electric current cannot be used to operate

Transformers

If undisturbed, an electric current in a superconducting wire loop

Will continue indefinitely

A magnet does not exert a force on

a stationary electric charge

The electrons in an atom

are some distance away from the nucleus

negative electric charge

interacts with both positive and negative charges

In an electromagnetic wave, the electric field is

perpendicular to both the magnetic field and the wave direction

A volt is a unit of electric:

potential difference

When the American flag is viewed with red light it appears

red and black

The setting sun appears red because its light is

scattered