A 400, 2.4-W resistor is needed, but only several 400, 1.2

Chapter 26, Problem 56P

(choose chapter or problem)

A 400?, 2.4-W resistor is needed, but only several 400?, 1.2 W resistors are available (see below Exercise). (a) What two different combinations of the available units give the required resistance and power rating? (b) For each of the resistor networks from part (a), what power is dissipated in each resistor when 2.4 W is dissipated by the combination? EXERCISE: Power Rating of a Resistor. The power rating of a resistor is the maximum power the resistor can safely dissipate without too great a rise in temperature and hence damage to the resistor. (a) If the power rating of a 15-k? resistor is 5.0 W, what is the maximum allowable potential difference across the terminals of the resistor? (b) A 9.0-k? resistor is to be connected across a 120-V potential difference. What power rating is required? (c) A 100.0-? and a 150.0-? resistor, both rated at 2.00 W, are connected in series across a variable potential difference. What is the greatest this potential difference can be without overheating either resistor, and what is the rate of heat generated in each resistor under these conditions?