Instructions: For problems where you need to write in answers, correct units (SI
ID: 1796429 • Letter: I
Question
Instructions: For problems where you need to write in answers, correct units (SI system) must accompany the units. Leaving off the units will cost you 1/3 rd the points for that answer, if the number is correet 1) (12 points), (a) What is the force per meter of length on a straight wire carrying a5.3 A electric curent when rpendicular to a 0.57 Tuniform magnetic field? F-BT// (0.5.3)m) (b) What is the force per meter of etic field is 65 2) (20 points). A square coil of wire with side 1-4.5 cm containing 150 loops and is positioned perpendicular to a uniform 0.55 T magnetic field at t-0. (a) What is the magnetic flux through one loop of the wire? (b) What is the total magnetic flux through the coil of all the loops? The coil is quickly pulled from the field at a constant speed to a region where B is zero at t-0.1 s. Find (o) the rate of change in flux through one loop. (d) Find the emf potential/voltage induced in the coil 3) (10 points). Calculate the wavelength (a) of a 60 Hz electromagnetic (EM) wave; (b) the wavelength of a 89.3 MHz FM radio wave. (c) the wavelength of visible light at frequency 6.2x104 Hz. 4) (8 points). The antenna of a cell phone is designed as1/4 wavelength long. A particular cell phone has an 7.8 cm long straight rod antenna. Estimate the operating frequency of this phone.Explanation / Answer
1) a) F = ILBsin(theta)
Theta = 90 degree
F = ILB ======> F/L = IB = 5.3*0.57 = 3.021 N/m
(b) F/L = IB*sin(65) = 5.3*0.57*sin65 = 2.74 N/m
2) l = 4.5 cm = 0.045 m
A = l^2 = 0.002025 m^2
N = 150
B = 0.55 T
(a) Flux = BA = 0.55* 0.002025 = 0.00111375 Tm^2
(b) Flux = NBA = 150*0.55* 0.002025 = 0.1670625 Tm^2
(c) Rate of change of flux = NA(dB/dt) = 150*0.002025*0.55/0.1 = 1.670625 V
(d) Rate of change of flux = EMF = 1.670625 V
3) a) Wavelength = c/f = 3*10^8/60 = 5*10^6 m
b) Wavelength = c/f = 3*10^8/89.3*10^6 = 3.36 m
c) Wavelength = c/f = 3*10^8/6.2*10^14 = 4.84*10^-7 m = 484 nm