physics waves and field only 3 multiple choices?

Question

1. In simple harmonic motion, the speed is greatest at the point in the cycle when
A. the magnitude of the acceleration is a maximum.
B. the displacement is maximum.
C. the magnitude of the acceleration is a minimum.
D. the potential energy is a maximum.
E. the kinetic energy is a minimum.

my guess: C.

26. An infinitely long wire centered on the origin carries a 20-A current directed in the positive y
direction. Determine the magnetic field at the point x = 5.0 m on the x-axis.
A. 1.6 nT in the negative z direction
B. 8.0 T in the positive z direction
C. 2.5 nT in the negative z direction
D. 0.8 T in the negative z direction
E. None of the above

my solution: magnetic field = (μ I)/(2 π a) = 4 x 10^-7 / 2 x 5 ????

18. When a positive charge is released from rest in a uniform electric field and moves along the electric field line, it will move to a position of
A. higher electric potential and gain electric potential energy
B. higher electric potential and lose electric potential energy
C. lower electric potential and gain electric potential energy
D. lower electric potential and lose electric potential energy
E. equipotential and gain electric potential energy

no ideaaaaaa i am so lost


pls explain them tooooo. pls i am begging im pleading.. pls

Answer 1

1) You are right, answer is C.



In simple harmonic motion velocity is fastest when the sine wave crosses the x axis. At that point the Potential energy is zero. Use a weight hanging on a spring for example. When you pull the mass down from the rest point (the x axis) to some maximum negative amplitude point and hold it, the mass has zero KE and all PE. When you release the mass the spring turns that PE into KE and runs out of PE right at that starting position (x axis).



PE = mgh

For PE to be zero you have to use a value of zero for the gravity in the equation m*g*h

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26) answer is E.-- none of the above--



B = uo* I / 2 *pi * r

B = 8.0 * 10^-7 Tesla or 0.0000008 T in X plane

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18) I think answer is B.



When a positive charge is held back intentionally and a electric field force is attracting that positive charge then at that initial starting point the positive charge has all PE and no KE. When the charge is released and moves into the electric field it gives up it's PE and gains KE. In electric terms, KE is equivalent to higher electric potential



I'm looking at it in terms of how a battery works. A battery has a electric potential energy of 1.5V at so many amps. Not until you connect the battery to a load does the charges move. When they move, the battery loses it's stored up energy and the load gains that energy

Answer 2

1.C

2. μ I/(2 π a) =8*10^-7T

3. D



potential is equivalent of "elevation".



high potential is "high elevation" and represents higher potential energy (ability to do work).

when object is dropped from high elevation, it falls towards lower altitude. in process accumulates kinetic energy (at the expense of lost potential energy).

Answer 3

E = j2sin(kx – ωt) Magnetic flux density: B B = E/c = μoH Poynting vector: P = ExH · dS Power radiated by wave per unit area: P/A = (1/μo) ExB = (1/μoc) E² Electric field peak intensity: |E| = 2, |E|² = 4

= ½[1/(4πx10^-7)(3x10^8)] 4 = 2/120π = 0.0053 = 5.3 mW/m²