3 years ago

Evidence to a chemical and physical change "a straight piece of wire is coiled to form a spring

1 answer:

6 0

See when a chemical change happens the color and the look is changed. As when the paper or cardboard which is rough is burned, it changes into smooth black ash.

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the speed of sound in water is slower than the speed of air

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3 years ago

A piece of Nichrome wire has a radius of 6.5 104 m. It is used in a laboratory to make a heater that uses 4.00 102 W of power wh

Delvig [45]

Answer:

$L=4.8*10^{17}m$

Explanation:

Given data

Power P=4.00×10²W

Radius r=6.5×10⁴m

Voltage V=120V

To find

Length of wire L

Solution

We know that resistance of wire can be obtained from

$P=\frac{V_{2}}{R}\\ R=\frac{V_{2}}{P}$

We also know that R=pL/A solving the length noting that A=πr²

and using p=100×10⁻⁸Ω.m we find that

$L=\frac{RA}{p}\\ L=\frac{\frac{(V^{2})}{P}(\pi r^{2}) }{p} \\L=\frac{V^{2}(\pi r^{2})}{pP}\\ L=\frac{(120V)^{2}\pi (6.5*10^{4} m)^{2} }{100*10^{-8}(4.00*10^{2} W) }\\ L=4.8*10^{17}m$