Class Notes (838,058)
United States (325,292)
Physics (56)
PH 122 (46)
Lecture

# Electromagnetism, energy and field strength, intensity, polarization

3 Pages
111 Views

Department
Physics
Course
PH 122
Professor
Brian Jones
Semester
Spring

Description
26 March The speed of electromagnetic waves is the same for all waves regardless of wavelength A typical analog cell phone has a frequency of 850 MHz; a digital phone a frequency of 1950 MHz. Compared to the signal from an analog phone, the digital signal has shorter wavelength and higher photon energy. A radio tower emits two 50 W signals, one an AM signal at a frequency of 850 kHz, one an FM signal at a frequency of 85 MHz. Which signal has more photons per second? FM: higher frequency → higher photon energy Therefore the AM signal has more photons per second Energy and Field Strength Intensity of an electromagnetic wave with field amplitudes 0 and B0 P 2 c 2 I = A = ½ ϵ 0 0 ½ μ 0 B 0 Amplitude of magnetic field typically small 2I E 0 √cε 0 E 0 B 0 c E 0 cB 0 The Microwave Oven Inside the cavity of a microwave oven, the 2.4 GHz electromagnetic waves have an intensity of 5.0 kW/m2 What is the strength of the electric field? 3 2 I = 5.0 x 10 W/m 1,940 V/m The magnetic field? 6.5 μT Intensit
More Less

Related notes for PH 122
Me

OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Just a few more details

So we can recommend you notes for your school.