How much conventional current must you run in a solenoid with radius = 0.05 m and length = 0.39 m to produce a magnetic field inside the solenoid of 2 × 10−5 T, the approximate field of the Earth? The solenoid has 200 turns.

Karen is running forward at a speed of 9 m/s. she tosses her sweaty headband backward at a speed of 20 m/s. the speed of the headband, to the nearest whole number relative to a stationary observer watching karen

Balloon a has charge q, and identical mass balloon b has charge 10q. you hang them from threads near each other. choose all of the statements with which you agree. check all that apply. a. a and b exert the same magnitude forces on each other. b. the force that a exerts on b is 10 times the force that b exerts on a. c. the angle between the thread supporting a and the vertical is < the angle between the thread supporting b and the vertical. d. the force that a exerts on b is 1/10 the force that b exerts on a.

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?