The resistance of a tungsten bulb increases as it gets hotte

The resistance of a tungsten bulb increases as it gets hotter. How does this help explain why many bulbs bum out whe they are first turned on?

What physical characteristic determines the power rating of a resistor?

What is the smallest value of resistance that acan be used across 10V if the power dissipateed is not to exceed 0.5W?

Solution

Many bulbs are bulbs are burn out when they first ON because the resistance of a bulb opposes sudden current passing through it and increases its heat enormously causes to burn out immediately.

2. By using following physical characteristics 1. physical size 2. surface area

we determine the power rating of a resistor

3. Smallest value of Resistance that the power doesnot exceed 0.5watts is R=V^2/P= 100/0.5= 200 ohm