Consider two cylindrical conductors made of the same ohmic material. V1 ~E1 I1 ℓ1 r1 b V2 ~E2 I2 ℓ2 r2 b If rho2 = rho1 , r2 = 2 r1 , ℓ2 = 2 ℓ1 , and V2 = V1 , find the ratio R2 R1 of the resistances.

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

continuous conducting path for current, power supply

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