Assume the helium-neon lasers commonly used in student physics laboratories have power outputs of 0.250 mW. (a) If such a laser beam is projected onto a circular spot 3.40 mm in diameter, what is its intensity (in watts per meter squared)? 27.5 W/m² (b) Find the peak magnetic field strength (in teslas). 8.57e-7 X T (c) Find the peak electric field strength (in volts per meter). 144 V/m

Assume the helium-neon lasers commonly used in student physics laboratories have power outputs of 0.500 mW. (a) If such a laser beam is projected onto a circular spot 1.00 mm in diameter, what Is its Intensity? (b) Find the peak magnetic field strength. (C) Find the peak electric field strength.

The potential difference V(t) between parallel plates shown above is instantaneously increasing at a rate of 107V/s. What is the displacement current between the plates if the separation of the plates is 1.00 cm and they have an area of 0.200m2?

Suppose the maximum safe intensity of microwaves for human exposure is taken to be 1,00 W/m2. (a) If a radar unit leaks 10.0 W of microwaves (other than those sent by its antenna) uniformly in all directions, how far away must you be to be exposed to an intensity considered to be safe? Assume that the power spreads uniformly over the area of a sphere with no complications from absorption or reflection, (b) What is the maximum electric field strength at the safe intensity? (Note that early radar units leaked more than modem ones do. This caused identifiable health problems, such as cataracts, for people who worked near them.)

What is the maximum electric field strength in an electromagnetic wave that has a maximum magnetic field strength of 5.00104 (about 10 times Earth's magnetic field)?

A parallel-plate capacitor with plate separation d is connected to a source of emf that places a time-dependent voltage V(t) across its circular plates of radius r0and area (a) Write an expression for the time rate of change of energy inside the capacitor in terms of V(t) and dV(t)/ dt. (b) Assuming that V(t) is increasing with time, identify the directions of the elecuic field lines inside the capacitor and of the magnetic field lines at the edge of the region between the plates, and then the direction of the Poynting vector S at this location. (c) Obtain expressions for the time dependence of E(t), for B(t) from the displacement current, and for the magnitude of the Poynting vector at the edge of the region between the plates. (d) From S , obtain an expression In terms of ‘(t) and dV(t)/dt for the rate at which electromagnetic field energy the region between the plates. (e) Compare the results of pails (a) and (d) and explain the relationship between them.

Suppose a spherical particle of mass m and radius R in space absorbs light of intensity I for time t. (a) How much work does the radiation pressure do to accelerate the particle (mm rest In the given tine It absorbs the light? (b) How much energy canted by the electromagnetic waves is absorbed by the particle over this time based on the radiant energy incident on the particle?

What are the wavelengths of (a) X-rays of frequency 2.01017 Hz? (b) Yellow light of frequency 5.11014Hz ? (C) Gamma rays of frequency 1.01023Hz ?

A radio station broadcasts its radio waves with a power of 50,000 W. What would be the intensity of this signal if it is received on a planet orbiting Proxima Centuri, the closest star to our Sun, at 4.243 ly away?

What is the intensity of an electromagnetic wave with a peak electric field strength of 125 Vim?