Three of these are wrong. Find the one that holds.

Exercise and reference answers

Questions

1. Question

   Three of these statements about charge are false.

   Choices

   1. Item

      Charge is always an integral multiple of e

      Correct

      Yes

   2. Explanation

      Friction transfers charge; it never creates it.

      Item

      Charge can be created by friction

   3. Explanation

      Additivity means an ALGEBRAIC sum, signs included.

      Item

      Charges add ignoring their signs

   4. Explanation

      That contradicts quantisation.

      Item

      Charge may take any continuous value

2. Question

   Three of these statements about Coulomb's law are false.

   Choices

   1. Item

      Force falls as the inverse square of r

      Correct

      Yes

   2. Explanation

      The dependence is on r squared.

      Item

      Force falls as the inverse of r

   3. Explanation

      It depends on their product.

      Item

      Force depends on the sum of the charges

   4. Explanation

      It falls as separation grows.

      Item

      Force grows with separation

Explanation