# Physics

The heating element of a simple heater consists of a 2.2m--long, 0.70mm--diameter nichrome wire. When plugged into a 120 V outlet, the heater draws 7.5 A of current when hot.

I found that the wire's resistance when it was hot was 16 ohms. Now using this answer of 16 ohms calculate the resistivity of nichrome in this situation in units of ohms * m.

I can not get the answer. I have been using the formula R=pL/A which I rearranged to p=RA/L.

I got A by A=pie(7*10^-4)^2, which equals 1.54*10^-6.

I plugged in the numbers p=(16)(1.54*10^-6)/(2.2m) and got the answer 1.12*10^-5 but this isn't the right answer. I can not figure out what I did wrong. I would appreciate any help that gets me to the right answer! Thank you!!

1. 0
2. 0
3. 49
1. You need to divide the diameter by two because the equation requires the radius not the diameter.

1. 0
2. 0
posted by Alexis

## Similar Questions

1. ### physical science

The heating elements of an electric toaster is typically made of nichrome wire (an alloy of nickel and chromium). As current passes through the wires, the wires heat up, thus toasting the toast. Estimate the overall resistance of

asked by michelle on February 17, 2017
2. ### physics

As part of a class project you are given 0.900 g of nichrome and asked to fabricate a wire with uniform cross-section. You use up 95% of the nichrome and make a wire with a resistance of 0.840 Ω. The resistivity of nichrome is

asked by Justin on September 16, 2013
3. ### College Physics

A 1500-W heater is designed to be plugged into a 120-V outlet. What current will flow through the heating coil when the heater is plugged in? I = A What is R , the resistance of the heater? How long does it take to raise the

asked by Lanise on February 7, 2010
4. ### physics

A toaster uses a Nichrome heating wire. When the toaster is turned on at 20°C, the initial current is 1.50 A. A few seconds later, the toaster warms up and the current has a value of 1.22 A. The average temperature coefficient of

asked by rick on January 31, 2008
5. ### physics

A toaster uses a Nichrome heating wire. When the toaster is turned on at 20°C, the initial current is 1.50 A. A few seconds later, the toaster warms up and the current has a value of 1.20 A. The average temperature coefficient of

asked by Anonymous on February 28, 2010
6. ### physics

a toaster with 4m length of nichrome(resistivity is 150Ã—10^-8 and temperature coefficient of resistivity is 0.4Ã—10^-3/Â¤c) wire as its heating element is rated at 1050w and operates on 220v.the operating temperature of

asked by Anonymous on July 12, 2018
7. ### electricity

Is there any data about the use of nichrome heating, for instance: a nichrome element in the cables of electric kettles, geysers and spiral stove? What do you mean by "data"? What physical data are you looking for: resistivity?

asked by tigger needs help on February 7, 2007
8. ### Physics

Calculate the resistance per unit length of a nichrome wire, which has a radius of 0.436 mm. The resistivity of nichrome is 1.5×10−6 Ω·m. Answer in units of Ω/m If a potential difference of 20 V is maintained across a 3.7 m

asked by Kudo on February 25, 2012
9. ### Physics

A piece of Nichrome wire has a radius of 8.0 10-4 m. It is used in a laboratory to make a heater that dissipates 2.00 102 W of power when connected to a voltage source of 120 V. Ignoring the effect of temperature on resistance,

asked by Mary on September 7, 2007
10. ### Physics

A nichrome wire of diameter 5mm and length 5m has resistivity of 10^-4 ohm meter. If wire is compressed to double it's diameter. Find the resistance in its new form. Also find the resistance of the wire originally ?

asked by Kartik on November 20, 2016

More Similar Questions