Question 1

In order to keep its food hot,a restaurant will place it under which type of lamp?
A)infrared
B)visible light
C)ultraviolet
D)x-ray

Accepted Answer

Infrared lamps are commonly used in restaurants to keep food hot as they emit heat that can penetrate the food and keep it warm without overcooking it. Visible light, ultraviolet, and x-ray lamps are not suitable for this purpose.

Question 2

An ultraviolet light wave has a wavelength of 300 nm and speed of 1.96 × 10⁸ m/s through a transparent medium.What is the frequency of this wave in the medium? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s) A)1.00E+15 Hz B)3.27E+14 Hz C)6.53E+14 Hz D)6.53E+5 Hz E)1.28E+7 Hz

Accepted Answer

The formula to calculate frequency is:
frequency = (speed of light in vacuum) / wavelength

First, we need to convert the wavelength from nanometers to meters:
300 nm = 300 x 10^-9 m

Then, we can use the formula and substitute the values:
frequency = (3.00 x 10^8 m/s) / (300 x 10^-9 m)
frequency = 1.00 x 10^15 Hz

However, the wave is not travelling in a vacuum but through a transparent medium. Therefore, we need to use the given speed of the wave in the medium:
frequency = (1.96 x 10^14 m/s) / (300 x 10^-9 m)
frequency = 6.53 x 10^14 Hz

Therefore, the frequency of the ultraviolet light wave in the medium is 6.53 x 10^14 Hz, which corresponds to choice C.

Question 3

The Doppler shift for electromagnetic radiation from distant galaxies moving away from the observer is called a:
A)red shift.
B)blue shift.
C)black shift.
D)vacuum shift.

Accepted Answer

When a distant object is moving away from an observer, the wavelength of its electromagnetic radiation appears longer, and thus, the light shifts towards the red end of the spectrum. This is called the red shift, and it is one of the primary pieces of evidence for the expanding universe.

Question 4

A radio wave signal,which transmits at a frequency of 5.64 MHz,has what wavelength? (c = 3.00 × 10⁸ m/s) A)532 m B)106 m C)53.2 m D)167 m E)28.3 m

Accepted Answer

The formula to calculate wavelength is:

wavelength = speed of light / frequency

Plugging in the given values:

wavelength = 3.00 × 10^8 m/s / 5.64 MHz

Note that the frequency needs to be converted from MHz to Hz:

wavelength = 3.00 × 10^8 m/s / 5.64 × 10^6 Hz

wavelength = 53.2 meters

Therefore, the best choice is C) 53.2 m.

Question 5

Temperature variation of different parts of a person's body can be detected by analyzing the emission pattern of which type of electromagnetic radiation?
A)microwave
B)infrared
C)ultraviolet
D)x-rays

Accepted Answer

Infrared radiation is emitted by objects at different temperatures, including the human body. By analyzing the emission pattern of infrared radiation, it is possible to determine the temperature variation in different parts of a person's body. Microwave, ultraviolet, and x-rays are not typically used to detect temperature variation in the human body.

Question 6

Find the frequency of x-rays of wavelength 1.75 × 10−¹⁰ m.(c = 3 × 10⁸ m/s) A)1.71E+12 Hz B)3.43E+19 Hz C)1.71E+18 Hz D)3.43E+9 Hz E)4.29E+14 Hz

Accepted Answer

The frequency of x-rays can be calculated using the equation:
frequency = speed of light / wavelength
Substituting the given values, we get:
frequency = 3 × 10^8 m/s / (1.75 × 10^-11 m)
frequency = 1.71 × 10^18 Hz
Therefore, the best choice is C, with a frequency of 1.71E+18 Hz.

Question 7

An observer is moving in space toward a distant star at 50.0 km/s while the star is moving toward the observer at 180 km/s;the relative velocity being 230 km/s of approach.What relative change in frequency of the light from the star as seen by the observer? (The speed of light in space is 3.00 × 10⁵ km/s). A)0.077% increase B)0.077% decrease C)0.026% increase D)0.23% decrease E)0.23% increase

Accepted Answer

The relative change in frequency, or Doppler shift, can be calculated using the formula for relativistic Doppler effect, which simplifies to $\Delta f / f = v / c$ for velocities much less than the speed of light. Here, $v = 230$ km/s is the relative velocity and $c = 3.00 \times 10^5$ km/s is the speed of light. Thus, $\Delta f / f = 230 / 300000 = 0.00077$, or a 0.077% increase in frequency.

Question 8

As an electromagnetic wave travels through free space,its speed can be increased by:
A)increasing its frequency.
B)increasing its energy only.
C)increasing both its energy and momentum.
D)None of the above will increase its speed.

Accepted Answer

The speed of an electromagnetic wave through free space is determined solely by the properties of free space, namely, the permittivity and permeability of free space. Therefore, neither changing the frequency nor increasing the energy or momentum will increase the speed of the wave.

Question 9

In a 60-Hz RLC circuit,the phase angle is positive.The values of the resistance,inductance,and the capacitance are now doubled.Which of the following is now true about the phase angle?
A)It is still positive.
B)It could be zero.
C)It will be negative.
D)It could be positive,negative,or zero,but it cannot be greater than its original value.

Accepted Answer

Doubling the resistance, inductance, and capacitance in an RLC circuit does not change the sign of the phase angle. The phase angle's sign is determined by the dominant component (inductive or capacitive). If the phase angle was positive (indicating an inductive circuit where the voltage leads the current), doubling all components keeps the circuit inductively dominant, thus maintaining a positive phase angle.

Question 10

The electromagnetic radiation that causes tanning:
A)can produce cancer.
B)rarely passes through glass windows.
C)is absorbed by ozone.
D)is all of the above.

Accepted Answer

Electromagnetic radiation that causes tanning can produce cancer, rarely passes through glass windows, and is absorbed by ozone. Therefore, all of the above options are correct.

Question 11

In the Doppler effect for electromagnetic waves,which of the following gives the greatest shift in frequency?
A)the source moving toward the non-moving observer at speed v
B)the observer moving toward the non-moving source at speed v
C)the source moving toward the approaching observer,both at speed v/2
D)All of the above give the same shift.

Accepted Answer

The Doppler effect for electromagnetic waves, such as light, does not depend on the relative motion of the source and observer in the same way it does for sound. The observed frequency shift is determined by the relative velocity between the source and the observer. Therefore, whether the source is moving towards a stationary observer, the observer is moving towards a stationary source, or both are moving towards each other with equal but halved speeds, the relative velocity—and thus the frequency shift—is the same in all scenarios.

Question 12

Glass panes are opaque to a certain type of radiation,which passes through quartz.What type of radiation is it? This radiation is important in ozone layer reactions.
A)microwave
B)gamma
C)x-ray
D)ultraviolet

Accepted Answer

The radiation that is opaque to glass panes but passes through quartz is ultraviolet (UV) radiation. This type of radiation is important in ozone layer reactions, as it is responsible for the formation and breaking down of ozone molecules.

Question 13

A radar pulse sent out to an airplane at a distance of 24.9 km will return as an echo to the source in what time interval? (c = 3.00 × 10⁸ m/s) A)3.33E-5 s B)8.30E-5 s C)1.66E-4 s D)4.15E-5 s E)4.98E-4 s

Accepted Answer

The time interval for the radar pulse to return as an echo is calculated using the formula $time = \frac{distance}{speed}$. Since the radar pulse travels to the airplane and back, the total distance covered is $2 \times 24.9 \, km = 49.8 \, km = 49.8 \times 10^3 \, m$. The speed of the radar pulse is the speed of light, $c = 3.00 \times 10^8 \, m/s$. Therefore, the time interval is $time = \frac{49.8 \times 10^3}{3.00 \times 10^8} = 1.66 \times 10^{-4} \, s$.

Question 14

Star #1 is approaching the Earth with speed v.Star #2 is receding from the Earth with the same speed v.Measurements of the same spectral line from each of the stars show Doppler shifts in frequency.The light from which star will have the larger magnitude shift in frequency?
A)star #1
B)Both stars will have the same shift.
C)The value of the speed must be known before an answer can be found.
D)star #2

Accepted Answer

The answer of Star #1 is approaching the Earth with...

Question 15

Which type of electromagnetic wave has the largest wavelength?​
A)​gamma rays
B)​radio waves
C)​x-rays
D)​visible light

Accepted Answer

Radio waves have the largest wavelength, ranging from a few millimeters to thousands of kilometers. Gamma rays have the shortest wavelength, while X-rays and visible light have intermediate wavelengths.

Question 16

What is the wavelength of 97.6-MHz television EM waves? (c = 3 × 10⁸ m/s) A)6.15 cm B)3.07 m C)6.15 km D)12.3 m E)9.22 km

Accepted Answer

The wavelength ($\lambda$) can be calculated using the formula $\lambda = \frac{c}{f}$, where $c$ is the speed of light (3 × $10^8$ m/s) and $f$ is the frequency (97.6 MHz or 97.6 × $10^6$ Hz). Thus, $\lambda = \frac{3 \times 10^8}{97.6 \times 10^6} = 3.07$ meters.

Question 17

Of the various types of electromagnetic radiation,which is the most penetrating through all forms of matter?
A)infrared
B)gamma
C)visible light
D)ultraviolet

Accepted Answer

Gamma radiation has the highest energy and shortest wavelength among all types of electromagnetic radiation. This property allows it to penetrate through all forms of matter, including concrete and steel, making it the most penetrating form of electromagnetic radiation. In contrast, infrared, visible light, and ultraviolet radiation have lower energy levels and longer wavelengths, which limits their ability to penetrate through dense materials.

Question 18

The human eye is sensitive to light with wavelength down to 710 nm.What is the frequency of radiation at this wavelength? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s) A)4.23E+5 Hz B)4.42E+6 Hz C)4.23E+14 Hz D)4.37E+7 Hz E)2.18E+7 Hz

Accepted Answer

Using the formula λν=c, where λ is the wavelength, ν is the frequency, and c is the speed of light, we can solve for the frequency:
ν=c/λ=(3.00 × 10^8 m/s)/(710 × 10^-9 m)=4.23 × 10^14 Hz
Therefore, the answer is C.

Question 19

An object that is giving off only infrared electromagnetic waves is giving off heat through:
A)convection.
B)conduction.
C)radiation.
D)visible light.

Accepted Answer

Infrared electromagnetic waves are a form of electromagnetic radiation, which is the transfer of energy through space via electromagnetic waves. When an object is giving off only infrared electromagnetic waves, it means it is radiating heat energy in the form of infrared radiation. This is why infrared cameras are used to detect heat signatures - they are detecting the infrared radiation given off by the object. Convection and conduction involve the transfer of heat energy through physical contact or movement of fluids, whereas visible light is a completely different form of electromagnetic radiation.

Question 20

Microwave radiation is useful in which of the following?
A)sending phone messages
B)cooking food
C)aircraft navigation
D)All of the above are valid choices.

Accepted Answer

Microwave radiation is useful in all of the given choices. It is used in sending phone messages via cell phone networks, cooking food through microwave ovens, and in aircraft navigation through radar systems.

Quiz 21: Alternating-Current Circuits and Electromagnetic Waves

In order to keep its food hot,a restaurant will place it under which type of lamp?

An ultraviolet light wave has a wavelength of 300 nm and speed of 1.96 × 108 m/s through a transparent medium.What is the frequency of this wave in the medium? (1 nm = 10−9 m and c = 3.00 × 108 m/s)

The Doppler shift for electromagnetic radiation from distant galaxies moving away from the observer is called a:

A radio wave signal,which transmits at a frequency of 5.64 MHz,has what wavelength? (c = 3.00 × 108 m/s)

Temperature variation of different parts of a person's body can be detected by analyzing the emission pattern of which type of electromagnetic radiation?

Find the frequency of x-rays of wavelength 1.75 × 10−10 m.(c = 3 × 108 m/s)

As an electromagnetic wave travels through free space,its speed can be increased by:

In a 60-Hz RLC circuit,the phase angle is positive.The values of the resistance,inductance,and the capacitance are now doubled.Which of the following is now true about the phase angle?

The electromagnetic radiation that causes tanning:

In the Doppler effect for electromagnetic waves,which of the following gives the greatest shift in frequency?

Glass panes are opaque to a certain type of radiation,which passes through quartz.What type of radiation is it? This radiation is important in ozone layer reactions.

A radar pulse sent out to an airplane at a distance of 24.9 km will return as an echo to the source in what time interval? (c = 3.00 × 108 m/s)

Star #1 is approaching the Earth with speed v.Star #2 is receding from the Earth with the same speed v.Measurements of the same spectral line from each of the stars show Doppler shifts in frequency.The light from which star will have the larger magnitude shift in frequency?

Which type of electromagnetic wave has the largest wavelength?​

What is the wavelength of 97.6-MHz television EM waves? (c = 3 × 108 m/s)

Of the various types of electromagnetic radiation,which is the most penetrating through all forms of matter?

The human eye is sensitive to light with wavelength down to 710 nm.What is the frequency of radiation at this wavelength? (1 nm = 10−9 m and c = 3.00 × 108 m/s)

An object that is giving off only infrared electromagnetic waves is giving off heat through:

Microwave radiation is useful in which of the following?

An ultraviolet light wave has a wavelength of 300 nm and speed of 1.96 × 10⁸ m/s through a transparent medium.What is the frequency of this wave in the medium? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s)

A radio wave signal,which transmits at a frequency of 5.64 MHz,has what wavelength? (c = 3.00 × 10⁸ m/s)

Find the frequency of x-rays of wavelength 1.75 × 10−¹⁰ m.(c = 3 × 10⁸ m/s)

A radar pulse sent out to an airplane at a distance of 24.9 km will return as an echo to the source in what time interval? (c = 3.00 × 10⁸ m/s)

Which type of electromagnetic wave has the largest wavelength?

What is the wavelength of 97.6-MHz television EM waves? (c = 3 × 10⁸ m/s)

The human eye is sensitive to light with wavelength down to 710 nm.What is the frequency of radiation at this wavelength? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s)