Exam 21: Electromagnetic Induction and Faradays Law

Radiation of a single frequency reaches the upper atmosphere of the earth with an intensity of $1350 \mathrm {~W} / \mathrm { m } ^ { 2 }$ . What is the maximum value of the electric field associated with this radiation? $( c =$ $3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } , \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 }$ )

Which of the following statements about electromagnetic waves in free space are true? (There could be more than one correct choice.)

The maximum magnetic energy density of a sinusoidal electromagnetic wave is $8.95 \times 10 ^ { - 5 } \mathrm {~J} / \mathrm { m } ^ { 3 }$ . What is the amplitude of the magnetic field component of this wave? $\left( c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } , \mu _ { 0 } = 4 \pi \times \right.$ $10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 }$ )

A radio station broadcasts at $80 \mathrm { MHz }$ . How long does it take for this radio signal to travel a distance of $2.0 \times 10 ^ { 7 } \mathrm {~m}$ through space? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

How far does light travel in $1.0 \mu \mathrm { s }$ ? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

A cordless phone operates at $900 \mathrm { MHz }$ . What is the wavelength of the electromagnetic wave used by this phone? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

A light source radiates $60.0 \mathrm {~W}$ of single-wavelength sinusoidal light uniformly in all directions. What is the average intensity of the light from this bulb at a distance of $0.400 \mathrm {~m}$ from the bulb?

An 800-kHz sinusoidal radio signal is detected at a point $2.1 \mathrm {~km}$ distant from a transmitter tower. The electric field amplitude of the signal at that point is $0.80 \mathrm {~V} / \mathrm { m }$ . Assume that the signal power is radiated uniformly in all directions and that radio waves incident upon the ground are completely absorbed. What is the intensity of the radio signal at that point? $\left( \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 } , \mu _ { 0 } = \right.$ $\left. 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

Which one of the following lists gives the correct order of the electromagnetic spectrum from low to high frequencies?

At a particular point and instant, the magnetic field component of an electromagnetic wave is $15.0$ $\mu \mathrm { T }$ . What is the magnetic energy density of this wave at that point and instant? $\left( c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right.$ , $\mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 }$ )

A certain electromagnetic field traveling in vacuum has a maximum electric field of $1200 \mathrm {~V} / \mathrm { m }$ . What is the maximum magnetic field of this wave? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

The energy density of an electromagnetic wave in free space is

A sinusoidal electromagnetic wave has a peak electric field of $8.00 \mathrm { kV } / \mathrm { m }$ . What is the intensity of the wave? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } , \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 } \right)$

A light source radiates $60.0 \mathrm {~W}$ of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the electric field of this light at a distance of $0.400 \mathrm {~m}$ from the bulb? $\left( \varepsilon _ { 0 } = \right.$ $\left. 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 } , \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

The amplitude of the electric field for a certain type of electromagnetic wave is $570 \mathrm {~N} / \mathrm { C }$ . What is the amplitude of the magnetic field for that wave? $\left( c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

Two light beams of different frequency but the same intensity fall on a black (totally absorbing) surface, striking perpendicular to the surface. Which of the following statements are true? (There Could be more than one correct choice.)

A radar receiver indicates that a pulse return as an echo in $20 \mu \mathrm { s }$ after it was sent. How far away is the reflecting object? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

An 8.0-mW laser beam emits a cylindrical beam of single-wavelength sinusoidal light $0.90 \mathrm {~mm}$ in diameter. What is the rms value of the electric field in this laser beam? $\left( \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \right.$ . $\left. \mathrm { m } ^ { 2 } , \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

How far does a beam of light travel in $2.0 \mathrm {~ms}$ ? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

What is the maximum value of the magnetic field at a distance of $2.5 \mathrm {~m}$ from a light bulb that radiates $100 \mathrm {~W}$ of single-frequency sinusoidal electromagnetic waves uniformly in all directions? ( $\left. \varepsilon _ { 0 } = 8.85 \times 10 ^ { - 12 } \mathrm { C } ^ { 2 } / \mathrm { N } \cdot \mathrm { m } ^ { 2 } , \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } , c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$