An aurora occurs when
the earth's magnetic field is overwhelmed by charged ions
the moon moves in front of the sun
sunspots form on the surface of the sun
all of the above

To travel at constant speed, a car engine provides 24kw of useful power. the driving force on the car is 600n. at what speed does it travel?

This is the number of complete movements of a wave per second.

The electric field direction is defined by the direction of the force felt by (select one of the following answers): 1. a negative charge. 2. a positive charge. 3. both positive and negative charges.