7. A 100 W incandescent lamp has a resistance when cold (lamp extinguished) that is only 1/12 of its hot (lamp illuminated) resistance value. a) What is the lamp current and its hot resistance when placed across a 120 V line? b) What is the cold resistance of this lamp? c) What is the instantaneous current through the lamp at the moment it is switched on? d) What power does the lamp dissipate at this instant?

Immediately after the switch is closed: a) Rank the brightness of the light-bulbs from brightest to dimmest. b) After the switch has been closed a long time, has the brightness of bulb A, increased, decreased, or stay the same.

1. Consider the circuit below, consisting of a 1.5 V battery, a switch and four identical bulbs, labeled A - D. The switch is initially closed. 1.5 V B switch a. Rank the brightness of all four bulbs in the circuit. If any of the bulbs have equal brightness, state that explicitly. Explain your reasoning. (Remember to use the finger tracing method.)

Q1) What is current in terms of charge? a) Current is measured 2A in a DC circuit * How much charge is involved in the process? * How many electrons are involved in the process? * The voltage source of this current is 12 Volts. What is the power produced by the source?