The power rating of a resistor is the maximum power it can safely dissipate with

Question

The power rating of a resistor is the maximum power it can safely dissipate without getting too hot. Suppose you have a set of 5.60 Omega, 10.8 Omega, and 20.8 Omega resistors, all rated at 2.30 W.

A. If you connect these three resistors in series across a variable emf source of negligible internal resistance, what is the largest potential difference this emf source can be set to without damaging any of the resistors?
V= _______ V



B. Suppose you accidentally exceed the value in part (a). Which resistor will burn up first?
A. 5.60 Omega
B. 10.8 Omega
C. 20.8 Omega

Explanation / Answer

a) as they are connected in series current in all three resistors will be same let V be the emf of the battery then current = V/(37.2) power = i^2R = (V/37.2)^2 R if high resistance resistor is below the rating then remainig also will be on safeside so (V/37.2)^2 *20.8 = 2.3 V = 12.37 V b) 20.8 omega resistor will burn up first because it has high resistance value ..hence high power dissipated

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