1. identify each of the following as conductors or insulators.

19. cloth

20. dry wood

21. tap water

22. glass

2. light passes from air into water at an angle of 40.0° to the normal. what is the angle of refraction? show all work.

3. a rubber rod can be charged negatively when it is rubbed with wool. what happens to the charge of the wool?

4. what is electrical power in terms of current and potential difference?

5. generate an explanation for the following formula: p = i2r

6. three 15.0-w resistors are connected in parallel across a 30.0-v battery. show all work.

a) find the current through each branch of the circuit.

b) find the equivalent resistance of the circuit.

c) find the current through the battery.

7. what happens to the polarity of an electromagnet when the direction of the current passing through it is reversed?