Exam 32: Electromagnetic Waves

An 800-kHz radio signal is detected at a point 8.5 km distant from a transmitter tower.The electric field amplitude of the signal at that point is 0.90 V/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 average electromagnetic energy density at that point? ,μ₀ = 4π × 10^-7 T • m/A,

A microwave oven operates with sinusoidal microwaves at a frequency of 2400 MHz.The height of the oven cavity is 25 cm and the base measures 30 cm by 30 cm.Assume that microwave energy is generated uniformly on the upper surface of the cavity and propagates directly downward toward the base.The base is lined with a material that completely absorbs microwave energy.The total microwave energy content of the cavity is 0.50 µJ.What is the power output of the oven? (c = 3.00 × 10⁸ m/s, ,

A radiometer has two square vanes (each measuring 1.0 cm by 1.0 cm),attached to a light horizontal cross arm,and pivoted about a vertical axis through the center,as shown in the figure.The center of each vane is 6.0 cm from the axis.One vane is silvered and it reflects all radiant energy incident upon it.The other vane is blackened and it absorbs all incident radiant energy.An electromagnetic wave with an intensity of 0.30 kW/m² is incident normally upon the vanes.What is the electromagnetic power absorbed by the blackened vane? , μ₀ = 4π × 10^-7 T • m/A,ε₀ = 8.85 × 10^-12 C²/N • m²)

The y component of the electric field of an electromagnetic wave traveling in the +x direction through vacuum obeys the equation E_y = (375 N/C)cos[kx - (2.20 × 10¹⁴ rad/s)t].What is the wavelength of this electromagnetic wave? (c = 3.0 × 10⁸ m/s)

An electromagnetic wave has a peak electric field of 3.0 kV/m.What is the intensity of the wave? ,μ₀ = 4π × 10^-7 T • m/A,ε₀ = 8.85 × 10^-12 C²/N • m²)

An 800-kHz radio signal is detected at a point 4.5 km distant from a transmitter tower.The electric field amplitude of the signal at that point is 0.63 V/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 magnetic field amplitude of the signal at that point? , μ₀ = 4π × 10^-7 T • m/A, )

A sinusoidal electromagnetic wave in vacuum delivers energy at an average rate of 5.00 µW/m².What are the amplitudes of the electric and magnetic fields of this wave? ,μ₀ = 4π × 10^-7 T • m/A,ε₀ = 8.85 × 10^-12 C²/N • m²)