Acircular loop of diameter 10 cm, carrying a current of 0.20 a, is placed inside a magnetic field b⃗ =0.30 tk^. the normal to the loop is parallel to a unit vector n^=−0.60i^−0.80j^. calculate the magnitude of the torque on the loop due to the magnetic field.

Aspring with an unstrained length of 0.071 m and a spring constant of 2.6 n/m hangs vertically downward from the ceiling. a uniform electric field directed vertically upward fills the region containing the spring. a sphere with a mass of 5.29 10-3 kg and a net charge of +7.2 µc is attached to the lower end of the spring. the spring is released slowly, until it reaches equilibrium. the equilibrium length of the spring is 0.058 m. what is the magnitude of the external electric field?