¿Qué son las líneas de campo magnético? ¿Cómo van dirigidas?

Anne applies a force on a toy car and makes it move forward. what can be said about the forces acting on the toy car at the moment anne applies the force?

He viscosities of several liquids are being compared. all the liquids are poured down a slope with equal path lengths. the liquid with the highest viscosity will

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?