Question 1

You can raise the temperature of an object with
A) microwaves.
B) infrared waves.
C) ultraviolet rays.
D) all of the above.
E) only (a) and (b) above.

Accepted Answer

All of the options listed, microwaves, infrared waves, and ultraviolet rays, can increase the temperature of an object. Microwaves and infrared waves are commonly used for heating, while ultraviolet rays, despite being less commonly associated with heating, can also raise temperatures.

Question 2

Two identical silver spheres of mass m and radius r are placed a distance R (sphere 1) and 2R (sphere 2) from the sun respectively. The ratio of the gravitational force exerted by the sun on sphere 1 to the pressure of solar radiation on sphere 1 is T₁; the ratio for sphere 2 is T₂. The ratio of T₂ to T₁ is A) 0.25. B) 0.50. C) 1.0. D) 2.0. E) 4.0.

Accepted Answer

The gravitational force exerted by the sun on a sphere is proportional to the mass of the sphere and inversely proportional to the square of the distance between the sphere and the sun. The pressure of solar radiation on a sphere is proportional to the surface area of the sphere and inversely proportional to the square of the distance between the sphere and the sun. The ratio of the gravitational force to the pressure of solar radiation is therefore proportional to the ratio of the mass of the sphere to its surface area. Since the two spheres are identical, the ratio of their masses to their surface areas is the same. Therefore, the ratio of T2 to T1 is 1.

Question 3

The speed of light is given by the value of A) ε₀μ₀. B) . C) . D) . E) .

Accepted Answer

The answer of The speed of light is given by...

Question 4

Magnetic fields are produced by
A) constant electric currents.
B) electric currents that vary sinusoidally with time.
C) time-varying electric fields.
D) all of the above.
E) only (a) and (b) above.

Accepted Answer

Magnetic fields can be produced by constant electric currents, as shown by Ampere's law, and also by electric currents that vary sinusoidally with time, as in an electromagnet. Additionally, time-varying electric fields can produce magnetic fields according to Faraday's law. Therefore, all of the above choices are correct.

Question 5

A possible means of spaceflight is to place a perfectly reflecting aluminized sheet into Earth orbit and use the light from the sun to push this solar sail. If a huge sail of area 6.00 × 10⁵ m² and mass 6000 kg were placed into orbit and turned toward the sun, what would be the force exerted on the sail? (Assume a solar intensity of 1380 W/m².)

Accepted Answer

The answer of A possible means of spaceflight is to...

Question 6

The correct form of Ampere's law for circuits with gaps in them is
A)
 .
B)
 .
C)
 .
D)
 .
E)
 .

Accepted Answer

The answer of The correct form of Ampere's law for...

Question 7

A plane parallel plate capacitor has plates of 10 cm² area that are 1.0 mm apart. At an instant when charge is being accumulated on the plates at a rate of 12 nC/s, the displacement current between the plates is A) 1.06 × 10−¹⁶ A. B) 1.2 × 10−⁸ A. C) 8.85 × 10−⁹ A. D) 1.00 A. E) 1.36 A.

Accepted Answer

The displacement current between the plates of a capacitor is given by the expression $I_D = \epsilon_0\frac{d\Phi_E}{dt}$, where $\epsilon_0$ is the permittivity of free space and $\frac{d\Phi_E}{dt}$ is the rate of change of electric flux through the surface bounded by the plates.

The electric field between the plates of the capacitor due to a charge $Q$ on each plate is given by $E = \frac{Q}{\epsilon_0 A}$, where $A$ is the area of each plate. Since the plates are parallel, the electric flux through the surface bounded by the plates is $\Phi_E = EA$. Therefore, the rate of change of electric flux is $\frac{d\Phi_E}{dt} = A\frac{dE}{dt}$.

The rate of accumulation of charge on each plate is given by $\frac{dQ}{dt} = 12$ nC/s. Therefore, the electric field between the plates is changing at a rate of $\frac{dE}{dt} = \frac{\frac{dQ}{dt}}{\epsilon_0 A} = \frac{12 	imes 10^{-9}}{\epsilon_0(0.1^2)}$ V/m.

Substituting this value in the expression for displacement current, we get $I_D = \epsilon_0 A\frac{dE}{dt} = \epsilon_0(0.1^2)\frac{12	imes10^{-9}}{\epsilon_0(0.1^2)} = 12	imes10^{-9}$ A = 1.2 $\mu$A. Therefore, the best choice is B.

Question 8

At every instant the ratio of the magnitude of the electric to the magnetic field in an electromagnetic wave in vacuum is equal to
A) the speed of radio waves.
B) the speed of light.
C) the speed of gamma rays.
D) all of the above.
E) only (a) and (b) above.

Accepted Answer

The ratio of the magnitude of the electric field to the magnetic field in an electromagnetic wave in vacuum is equal to the speed of light, which is the same for all electromagnetic waves, including radio waves and gamma rays.

Question 9

The sun radiates energy at a rate of 3.86 × 10²⁶ W. Its radius is 7.0 × 10⁸ m. If the distance from the Earth to the sun is 1.5 × 10¹¹ m, what is the intensity of solar radiation at the top of the Earth's atmosphere?

Accepted Answer

The answer of The sun radiates energy at a rate...

Question 10

An open circuit consists of a 12 μF parallel plate capacitor charged to 200 V and a 10 Ω resistor. At the instant when a switch closes the circuit (with no battery in it) the displacement current between the plates of the capacitor is A) 1.2 μA. B) 2.4 × 10−⁴ A. C) 2.4 mA. D) 10 A. E) 20 A.

Accepted Answer

The answer of An open circuit consists of a 12...

Question 11

Two identical silver spheres of mass m and radius r are placed a distance R (sphere 1) and 2R (sphere 2) from the sun respectively. The ratio of the pressure of solar radiation on sphere 2 to that on sphere 1 is
A) 0.25.
B) 0.50.
C) 1.0.
D) 2.0.
E) 4.0.

Accepted Answer

The pressure of solar radiation on a surface is given by $P = \frac{2I}{c}$, where $I$ is the intensity of solar radiation (power per unit area) and $c$ is the speed of light. Since the spheres are identical, their areas are equal and the intensity of solar radiation is the same for both spheres.

The force on a sphere due to radiation pressure is given by $F = PA$, where $A$ is the area of the sphere. Since the spheres are identical, their areas are equal, so the force on sphere 2 is four times the force on sphere 1 (because the distance is doubled, the area of the sphere "seen" by the Sun is four times as large). Therefore, the ratio of the pressures on the two spheres is:

$$\frac{P_2}{P_1} = \frac{F_2/A}{F_1/A} = \frac{4F_1}{F_1} = 4 \cdot \frac{2I/c}{2I/c} = 4 \cdot 1 = 4$$

Therefore, the correct answer is A) 0.25, because the pressure on sphere 2 is one-fourth the pressure on sphere 1.

Question 12

Near the surface of the planet, the Earth's magnetic field is about 0.50 × 10−⁴ T. How much energy is stored in 1.0 m³ of the atmosphere because of this field?

Accepted Answer

The answer of Near the surface of the planet, the...

Question 13

In the atmosphere, the shortest wavelength electromagnetic waves are called
A) microwaves.
B) infrared waves.
C) ultraviolet waves.
D) X-rays.
E) gamma rays.

Accepted Answer

Gamma rays have the shortest wavelength among the options listed, making them the highest energy electromagnetic waves in the atmosphere.

Question 14

When E and B are the amplitudes of the electric and magnetic fields in an electromagnetic wave in vacuum, the total average energy density in the wave is A) . B) . C) ε₀E². D) . E) .

Accepted Answer

The answer of When E and B are the amplitudes...

Question 15

The intensity of radiation reaching the earth from the sun is 1 350 W/m². The earth's radius is 6.4 × 10⁶ m. How big a force does this radiation exert on the earth? (Assume it is all absorbed.) A) 5.8 × 10⁸ N B) 1.2 × 10⁹ N C) 2.3 × 10⁹ N D) 4.6 × 10⁹ N E) 1.7 × 10¹⁷ N

Accepted Answer

The force exerted by the radiation can be found using the formula $F = \frac{Power}{c}$, where $c$ is the speed of light ($3 \times 10^8 m/s$). First, calculate the total power absorbed by the Earth using the given intensity and the cross-sectional area of the Earth ($\pi r^2$), where $r$ is the Earth's radius. The total power ($P$) absorbed is $1350 \times \pi \times (6.4 \times 10^6)^2$. Then, $F = \frac{P}{c}$. Plugging in the values, you get a force of approximately $5.8 \times 10^{18} N$.

Question 16

In an electromagnetic wave, 1) how are the electric and magnetic field directions related and 2) how is the direction of travel determined from their directions? (  is the velocity of the light wave.)
A)
 .
B)
 .
C)
 .
D)
 .
E)
 .

Accepted Answer

1) The electric and magnetic field directions in an electromagnetic wave are perpendicular to each other. Therefore, if the electric field is in the x direction, the magnetic field will be in the y or z direction.
2) The direction of travel of the electromagnetic wave is perpendicular to both the electric and magnetic fields, and is given by the right-hand rule. If you curl your right hand fingers in the direction of the electric field and then curl them in the direction of the magnetic field, your thumb will give you the direction of travel of the wave.

Question 17

High frequency alternating current is passed through a solenoid that contains a solid copper core insulated from the coils of the solenoid. Which statement is correct?
A) A copper core remains cool no matter what the frequency of the current in the solenoid is.
B) The copper core remains cool because the induced emf is parallel to the solenoid axis and fluctuates rapidly.
C) The copper core heats up because an emf parallel to the solenoid axis is induced in the core.
D) The copper core heats up because circular currents around its axis are induced in the core.
E) The copper core heats up because the electric field induced in the copper is parallel to the magnetic field produced by the solenoid.

Accepted Answer

The copper core heats up due to the induction of circular currents, known as eddy currents, around its axis. These currents are induced by the changing magnetic field produced by the high frequency alternating current in the solenoid.

Question 18

Since ε₀ = 8.85 × 10−¹² C² / N ⋅ m², the units of ε₀E² can be reduced to A) . B) . C) . D) . E) .

Accepted Answer

The answer of Since ε₀ = 8.85 × 10−¹² C²...

Question 19

The magnetic field amplitude in an electromagnetic wave in vacuum is related to the electric field amplitude by B =
A)
 .
B)
 .
C) E.
D)
 .
E) cE.

Accepted Answer

The answer of The magnetic field amplitude in an electromagnetic...

Question 20

A spherical particle of density and 2.00 mm radius is located at the same distance from the Sun as the Earth. R_SE = 1.5 × 10¹¹ m. . If the particle absorbs 100 percent of the sunlight reaching it, the ratio of the force exerted by the solar radiation to the force of gravity exerted on the particle by the Sun is A) 5.8 × 10−⁵. B) 0.58. C) 1.0. D) 1.7. E) 1.7 × 10⁴.

Accepted Answer

The answer of A spherical particle of density  and...

Quiz 34: Electromagnetic Waves

You can raise the temperature of an object with

The speed of light is given by the value of

Magnetic fields are produced by

The correct form of Ampere's law for circuits with gaps in them is

A plane parallel plate capacitor has plates of 10 cm2 area that are 1.0 mm apart. At an instant when charge is being accumulated on the plates at a rate of 12 nC/s, the displacement current between the plates is

At every instant the ratio of the magnitude of the electric to the magnetic field in an electromagnetic wave in vacuum is equal to

The sun radiates energy at a rate of 3.86 × 1026 W. Its radius is 7.0 × 108 m. If the distance from the Earth to the sun is 1.5 × 1011 m, what is the intensity of solar radiation at the top of the Earth's atmosphere?

An open circuit consists of a 12 μF parallel plate capacitor charged to 200 V and a 10 Ω resistor. At the instant when a switch closes the circuit (with no battery in it) the displacement current between the plates of the capacitor is

Two identical silver spheres of mass m and radius r are placed a distance R (sphere 1) and 2R (sphere 2) from the sun respectively. The ratio of the pressure of solar radiation on sphere 2 to that on sphere 1 is

Near the surface of the planet, the Earth's magnetic field is about 0.50 × 10−4 T. How much energy is stored in 1.0 m3 of the atmosphere because of this field?

In the atmosphere, the shortest wavelength electromagnetic waves are called

When E and B are the amplitudes of the electric and magnetic fields in an electromagnetic wave in vacuum, the total average energy density in the wave is

The intensity of radiation reaching the earth from the sun is 1 350 W/m2. The earth's radius is 6.4 × 106 m. How big a force does this radiation exert on the earth? (Assume it is all absorbed.)

In an electromagnetic wave, 1) how are the electric and magnetic field directions related and 2) how is the direction of travel determined from their directions? ( is the velocity of the light wave.)

High frequency alternating current is passed through a solenoid that contains a solid copper core insulated from the coils of the solenoid. Which statement is correct?

Since ε0 = 8.85 × 10−12 C2 / N ⋅ m2, the units of ε0E2 can be reduced to

The magnetic field amplitude in an electromagnetic wave in vacuum is related to the electric field amplitude by B =

A plane parallel plate capacitor has plates of 10 cm² area that are 1.0 mm apart. At an instant when charge is being accumulated on the plates at a rate of 12 nC/s, the displacement current between the plates is

The sun radiates energy at a rate of 3.86 × 10²⁶ W. Its radius is 7.0 × 10⁸ m. If the distance from the Earth to the sun is 1.5 × 10¹¹ m, what is the intensity of solar radiation at the top of the Earth's atmosphere?

Near the surface of the planet, the Earth's magnetic field is about 0.50 × 10−⁴ T. How much energy is stored in 1.0 m³ of the atmosphere because of this field?

The intensity of radiation reaching the earth from the sun is 1 350 W/m². The earth's radius is 6.4 × 10⁶ m. How big a force does this radiation exert on the earth? (Assume it is all absorbed.)

Since ε₀ = 8.85 × 10−¹² C² / N ⋅ m², the units of ε₀E² can be reduced to