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4 years ago

Choose true or false for each statement regarding the resistance of a wire.

Physics

1 answer:

weeeeeb [17]4 years ago

7 0

Answer:

1. True

2. True

3. False

Explanation:

According to Ohm's law, V = IR where V is the voltage, I is the current and R is the resistance. So if V is constant, R is inversely proportional to I

1. The resistivity of metal wires would depend on the temperature, this is true.

2. When length L of a wire decreases, the resistance R decreases as well, this would make I increase.

3. When the resistivity increases, resistance R increases as well, this would make I decrease.

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A copper wire and a tungsten wire of the same length have the same resistance. What is the ratio of the diameter of the copper w

spayn [35]

Answer:

Therefore the ratio of diameter of the copper to that of the tungsten is

$\sqrt{3} :\sqrt{10}$

Explanation:

Resistance: Resistance is defined to the ratio of voltage to the electricity.

The resistance of a wire is

directly proportional to its length i.e $R\propto l$
inversely proportional to its cross section area i.e $R\propto \frac{1}{A}$

Therefore

$R=\rho\frac{l}{A}$

ρ is the resistivity.

The unit of resistance is ohm (Ω).

The resistivity of copper(ρ₁) is 1.68×10⁻⁸ ohm-m

The resistivity of tungsten(ρ₂) is 5.6×10⁻⁸ ohm-m

For copper:

$A=\pi r_1^2 =\pi (\frac{d_1}{2} )^2$

$R_1=\rho_1\frac{l_1}{\pi(\frac{d_1}{2})^2 }$

$\Rightarrow (\frac{d_1}{2})^2=\rho_1\frac{l_1}{\pi R_1 }$ ......(1)

Again for tungsten:

$R_2=\rho_2\frac{l_2}{\pi(\frac{d_2}{2})^2 }$

$\Rightarrow (\frac{d_2}{2})^2=\rho_2\frac{l_2}{\pi R_2 }$ ........(2)

Given that $R_1=R_2$ and $l_1=l_2$

Dividing the equation (1) and (2)

$\Rightarrow\frac{ (\frac{d_1}{2})^2}{ (\frac{d_2}{2})^2}=\frac{\rho_1\frac{l_1}{\pi R_1 }}{\rho_2\frac{l_2}{\pi R_2 }}$

$\Rightarrow( \frac{d_1}{d_2} )^2=\frac{1.68\times 10^{-8}}{5.6\times 10^{-8}}$ [since $R_1=R_2$ and $l_1=l_2$ ]

$\Rightarrow( \frac{d_1}{d_2} )=\sqrt{\frac{1.68\times 10^{-8}}{5.6\times 10^{-8}}}$

$\Rightarrow( \frac{d_1}{d_2} )=\sqrt{\frac{3}{10}}$

$\Rightarrow d_1:d_2=\sqrt{3} :\sqrt{10}$

Therefore the ratio of diameter of the copper to that of the tungsten is

$\sqrt{3} :\sqrt{10}$

8 0

4 years ago

What are the three reasons cells divide?

hoa [83]

1 growth. Go from one cell/( zygote to a trillion)
2 replace. Repair\ 50 million cells die second.
3 reproduction. ( make cells for reproduction make specialized sex cells)

7 0

4 years ago

2. Four metal mugs with lids each contain the same volume of hot water at the same temperature. The mugs are made from the same

olga_2 [115]

Answer:

D. the mug painted dull black

4 0

2 years ago

Which scenario would be classified as a conceptual model

den301095 [7]

Answer:

Heyo! (Ish Mash Potato) XD

Explanation:

A conceptual model is a representation of a system, made of the composition of concepts which are used to help people know, understand, or simulate a subject the model represents. It is also a set of concepts. Some models are physical objects; for example, a toy model which may be assembled, and may be made to work like the object it represents.

Hope Mr. Mash Potato Helped!!!

3 0

3 years ago

Read 2 more answers

A car is driven 13 mi east and then certain distance due north, ending up at the position 25 degrees north of east of its initia

Kobotan [32]

Answer: Hello mate!

lets define the north as the y-axis and east as the x-axis.

Using the notation (x,y) we can define the initial position of the car as (0,0)

then the car travells 13 mi east, so now the position is (13,0)

then the car travels Y miles to the north, so the position now is (13, Y)

and we know that the final position is 25° degrees north of east of the initial position. This angle says that the distance traveled to the north is less than 13 mi because this angle is closer to the x-axis (or east in this case).

This angle is measured from east to north, then the adjacent cathetus is on the x-axis, in this case, 13mi

And we want to find the distance Y, so we can use the tangent:

Tan(25°) = Y/13

tan(25°)*13 mi = Y = 6.06 mi.

3 0

3 years ago