Overview
ReadOpen Stax: 9.1 - 9.5Links to an external site.
Complete the problems.
- A cylindrical rod has resistance R. If we triple its length (L) and diameter (D), what is its resistance, in terms of R? You can start with the formula for R and resistivity found in the Module.
- A cylindrical rod has resistivity ρ. If we triple its length (L) and diameter (D), what is its resistivity, in terms of ρ?
- During lightning strikes from a cloud to the ground, currents as high as 25,000 A can occur and last for about 40 μs How much charge is transferred from the cloud to the earth during such a strike?
- Consider the circuit shown below. The terminal voltage (Vab) of the 24.0 V ( ) battery is 21.2 V. What are (a) the internal resistance r of the battery and (b) the resistance R of the circuit resistor?
[Image unavailable: Battery and resistor circuit.]
5. The power rating of a light bulb (such as a 100 W bulb) is the power it dissipates when connected across a 120 V potential difference. What is the resistance of (a) a 100 W bulb and (b) a 60 W bulb? (c) How much current does each bulb draw in normal use?
6. An electric heater is constructed by applying a potential difference of 110 V to a nichrome wire of total resistance 8 . What are the (a) current carried by the wire and (b) power rating of the heater.
Nichrome is a nickel-chromium alloy that has a high melting point and is often used to make heating elements such as toaster coils.