10. one point, from Lecture 10, some covered in Lecture 6, a group question, involves words

(a) .2 Why doesn't it fall down? What are two differences between the force of gravity and the force of electricity? (.2)

(b) .4 Causality. Give two properties of a causal relationship. (.2)
How does Newton's concept of action at a distance violate causality? (.1)
How does Faraday's concept of field guarantee causality? (.1)

(c) .4 Fields. What is the difference between the field lines in general in electricity and magnetism? (.2)
What is the relation between a force and a field? (.1)
How can something (a field) be real but intangible? (.1)

Revised September 22, 1997.