91影视

Draw gravitational field lines between 2 masses, electric field lines between a positive and a negative charge, electric field lines between 2 positive charges and magnetic field lines around a magnet. Qualitatively describe the differences between the fields and the entities responsible for the field lines.

What is the direction of a current that experiences the magnetic force shown in each of the three cases in Figure${}^{\mathbf{22}\mathbf{.}\mathbf{54}}$, assuming the current runs perpendicular to B?

What is the direction of the magnetic field that produces the magnetic force shown on the currents in each of the three cases in Figure${}^{\mathbf{22}\mathbf{.}\mathbf{55}}$, assuming ${}^{\mathbf{B}}$is perpendicular to${}^{\mathbf{I}}$?

(a) What is the force per meter on a lightning bolt at the equator that carries ${}^{\mathbf{20}\mathbf{,}\mathbf{000}\mathbf{}\mathbf{A}}$perpendicular to the Earth鈥檚${}^{\mathbf{3}\mathbf{.}\mathbf{00}\mathbf{脳}{\mathbf{10}}^{\mathbf{-}\mathbf{5}}\mathbf{鈥�}\mathbf{T}}$field? (b) What is the direction of the force if the current is straight up and the Earth鈥檚 field direction is due north, parallel to the ground?

(a) A DC power line for a light-rail system carries${}^{\mathbf{1000}\mathbf{}\mathbf{A}}$at an angle of${}^{\mathbf{30}\mathbf{.}{\mathbf{0}}^{\mathbf{掳}}}$to the Earth鈥檚 ${}^{\mathbf{5}\mathbf{.}\mathbf{00}\mathbf{脳}{\mathbf{10}}^{\mathbf{-}\mathbf{5}}\mathbf{-}\mathbf{}\mathbf{T}}$field. What is the force on a${}^{\mathbf{10}\mathbf{鈥�}\mathbf{m}}$ section of this line? (b) Discuss practical concerns this presents, if any.

What force is exerted on the water in an MHD drive utilizing a${}^{\mathbf{25}\mathbf{.}\mathbf{0}\mathbf{鈥�}\mathbf{cm}}$-diameter tube, iflocalid="1654594579558" ${}^{\mathbf{100}\mathbf{鈥�}\mathbf{A}}$current is passed across the tube that is perpendicular to alocalid="1654594587153" ${}^{\mathbf{2}\mathbf{.}\mathbf{00}\mathbf{鈥�}\mathbf{T}}$magnetic field? (The relatively small size of this force indicates the need for very large currents and magnetic fields to make practical MHD drives.)

A wire carrying a $\mathbf{30}\mathbf{.}\mathbf{0}\mathbf{鈥�}\mathit{A}$current passes between the poles of a strong magnet that is perpendicular to its field and experiences a $\mathbf{2}\mathbf{.}\mathbf{16}\mathbf{鈥�}\mathit{N}$force on the $\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{}\mathit{c}\mathit{m}$ of wire in the field. What is the average field strength?

Question: A wire carrying a${}^{\mathbf{30}\mathbf{.}\mathbf{0}\mathbf{鈥�}\mathbf{A}}$current passes between the poles of a strong magnet that is perpendicular to its field and experiences a${}^{\mathbf{2}\mathbf{.}\mathbf{16}\mathbf{鈥�}\mathbf{N}}$force on the${}^{\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{cm}}$of wire in the field. What is the average field strength?

A 0.750-m-long section of cable carrying current to a car starter motor makes an angle of 60潞 with the Earth鈥檚${}^{\mathbf{5}\mathbf{.}\mathbf{50}\mathbf{脳}{\mathbf{10}}^{\mathbf{-}\mathbf{5}}}\mathbf{}\mathbf{T}$field. What is the current when the wire experiences a force of localid="1653896077054" $\mathbf{7}\mathbf{.}\mathbf{00}\mathbf{脳}{\mathbf{10}}^{\mathbf{鈥�}\mathbf{3}}\mathbf{}\mathbf{}\mathit{N}$? (b) If you run the wire between the poles of a strong horseshoe magnet, subjecting 5.00 cm of it to a 1.75-T field, what force is exerted on this segment of wire?

(a) A 0.750-m-long section of cable carrying current to a car starter motor makes an angle of 60潞 with the Earth鈥檚 ${}^{\mathbf{5}\mathbf{.}\mathbf{50}\mathbf{脳}{\mathbf{10}}^{\mathbf{鈥�}\mathbf{5}}}$field. What is the current when the wire experiences a force of ${}^{\mathbf{7}\mathbf{.}\mathbf{00}\mathbf{脳}{\mathbf{10}}^{\mathbf{鈥�}\mathbf{3}}}$? (b) If you run the wire between the poles of a strong horseshoe magnet, subjecting 5.00 cm of it to a 1.75-T field, what force is exerted on this segment of wire?