Consider a magnetic dipole with north and south poles, each of magnetic strength p/2, separated by a distance 2d. what is the magnitude of the magnetic field at a distancex from the middle of the dipole along the axis that connects the north and south poles? ci me: d 15 d tt lit b. consider now a solenoid with n loops, length 2a, radius r and resistance r. calculate the magnetic flux, p, of the magnetic field above through the area of the coil. in doing this, assume one-dimensional geometry in the (x- axis) only.
c. assume that the magnet above is attached to the end of a pendulum, such that x then, calculate the induced emf on the coil a = - x cos wt. dp dt dt dx

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

inverse v=i*r

nice nice