🎁BACK-TO-SCHOOL DEAL. Subscribe Now to get 40% OFF at only 8.49 USD/month, only valid until Sep 30th, 2024

Question

A circular loop of flexible iron wire has an initial circumference of 165.0 cm, but its circumference is decreasing at a constant rate of 12.0 cm>s due to a tangential pull on the wire. The loop is in a constant, uniform magnetic field ori- ented perpendicular to the plane of the loop and with magnitude 0.500 T. (a) Find the emf induced in the loop at the instant when 9.0 s have passed. (b) Find the direction of the induced current in the loop as viewed looking along the direction of the magnetic field. 

Asked By StormySkies20 at

Answered By Expert

Anthony

Expert · 2.1k answers · 2k people helped

Step 1/4

The initial circumference of the coil `c` is `165cm`The rate of decrease in the circumference `"dc"/"dt"` is `12.0"cm"/s`The magnetic field `B` is `0.500T`

Explanation:

A fundamental tenet of physics called Faraday's Law of Electromagnetic Induction outlines the connection between a shifting magnetic field & the induction of an electromotive force within a circuit or conducting loop.

Step 2/4

(a)

Calculate the rate of change of circumference as follows.

`"dc"/"dt" = (d(2pir))/"dt"`

`"dc"/"dt" = 2pi(dr)/"dt"`

`(dr)/"dt" = 1/(2pi)"dc"/"dt"`

`(dr)/"dt" = 1/(2pi)*12.0`

`(dr)/"dt" = 12/(2pi)"cm"/s`

`(dr)/"dt" = 0.12/(2pi)"cm"/s" "" "...(1)`

Calculate the rate of change of area of circular loop as follows.

`"dA"/"dt" = (d(pir^2))/"dt"`

`"dA"/"dt" = 2pir"dr"/"dt"`

`"dA"/"dt" = 2pi"r"*0.12/(2pi)`

`"dA"/"dt" = "r"*0.12`

`"dA"/"dt" = c/(2pi)*0.12" "" "...(2)`

Explanation:

Here, the circumference `c` is given by `2pir` and the area is given by `pir^2`

Step 3/4

(a), continuation

Write the expression for circumference as follows.

`c = 165-"dc"/"dt"*t`

`c = 165-12*9`

`c = 57cm" "" "...(2)`

Substitute in the formula for change in magnetic flux as follows.

`(dphi)/(dt) = B"dA"/"dt"`

`(dphi)/(dt) = 0.500*c/(2pi)*0.12`

`(dphi)/(dt) = 0.500*0.57/(2pi)*0.12`

`(dphi)/(dt) = 5.44*10^-3mV`

The EMF induced is equal to the change in magnetic flux.

`E = (dphi)/(dt)`

`E = 5.44*10^-3mV`

Explanation:

Here, `mV` stands for mili-volts.

Step 4/4

(b)

Explanation:

The "Right-Hand Thumb Rule" is also known as "Right-Hand Grip Rule"

Final Answer

(a), emf induced in the loop at the instant when `9.0 s` have passed is `5.44*10^-3mV`

(b), clockwise

🧑‍🏫 More Questions

Name Section Experiment 10 Advance Study Assignment: Analysis of an Aluminum-Zinc Alloy 1. On the following page, construct a graph of No, vs. % Al. To do this, refer to Equation 11 and the discus- sion preceding it. Note that a plot of N vs. % Al should be a straight line (why?). To fix the position of a straight line, it is necessary to locate only two points. The most obvious way to do this is to find No, when % Al = 0 and when % A1 = 100. If you wish you may calculate some intermediate points (for example, Nu, when % Al = 50, or 20, or 70); all these points should lie on the same straight line. To use a spread- sheet, set up Equation 11 for different Al percentages. Graph Nyt, vs. % Al. 2. A student obtained the following data in this experiment. Fill in the blanks in the data and make the indicated calculations: Mass of gelatin capsule 0.1134 g 23°C Ambient temperature, 23+273=296 Mass of capsule plus alloy sample 0.3218 g Ambient temperature, T 296 K Mass of alloy sample, m g Atmospheric pressure 732 mm Hg Vapor pressure of H20 at 1 (Appendix I) Mass of empty beaker 154.3 g mm Hg Mass of beaker plus displaced water 401.6 g Mass of displaced water Pressure of dry H2 g PH, (Eq. 7) mm Hg Volume of displaced water (density = 1.00 g/mL) atm mL Pressure of dry HZ L Volume, V, of H2 = Volume of displaced water mL = Find the number of moles of H, evolved, nu, (Eq. 5; V in liters, Pit in atm, T in K, R= 0.0821 liter- atm/mole K). moles H2 Find, NH, the number of moles of H, per gram of sample (Mu,m). moles H/g Find the % Al in the sample from the graph prepared for Problem 1. % Al Find the % Al in the sample by using Equation 11. % A006C Advance Study Assignment: Analysis of an Aluminum-Zinc Alloy 0.050 0.040 0.030 VHA 0.020 0.010 25% 50% 75% 100% % AI (11) 100-%A1 -X0.0153 + 100 in Nu = (100X0.0556) We can solve Equation 11 directly for % Al if we know the number of moles of H, evolved per gram of sample. To save time in the laboratory and to avoid arithmetic errors, it is highly desirable to prepare % Al in the sample can be read directly from the graph. Directions for preparing such a graph are given in advance a graph giving Nh, as a function of % Al. Then when Nh, has been determined in the experiment, Problem 1 in the Advance Study Assignment.

<span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1.2em;vertical-align:-0.35em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size1">(</span></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size1">)</span></span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mopen">(</span><span class="mord mathnormal">A</span><span class="mclose">)</span></span></span></span> That is, the null space of <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathnormal">A</span></span></span></span> can be determined by computing eigenvectors corresponding to the zero eigenvalue for <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8413em;"></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span></span></span></span>. (b) Let <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathnormal">A</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:3.6em;vertical-align:-1.55em;"></span><span class="minner"><span class="mopen"><span class="delimsizing mult"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:2.05em;"><span style="top:-2.25em;"><span class="pstrut" style="height:3.155em;"></span><span class="delimsizinginner delim-size4"><span>⎣</span></span></span><span style="top:-3.397em;"><span class="pstrut" style="height:3.155em;"></span><span style="height:0.016em;width:0.6667em;"><svg xmlns="http://www.w3.org/2000/svg" width='0.6667em' height='0.016em' style='width:0.6667em' viewBox='0 0 666.67 16' preserveAspectRatio='xMinYMin'><path d='M319 0 H403 V16 H319z M319 0 H403 V16 H319z'/></svg></span></span><span style="top:-4.05em;"><span class="pstrut" style="height:3.155em;"></span><span class="delimsizinginner delim-size4"><span>⎡</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:1.55em;"><span></span></span></span></span></span></span><span class="mord"><span class="mtable"><span class="arraycolsep" style="width:0.5em;"></span><span class="col-align-l"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:2.05em;"><span style="top:-4.21em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">1</span></span></span><span style="top:-3.01em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord mathnormal">ϵ</span></span></span><span style="top:-1.81em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">0</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:1.55em;"><span></span></span></span></span></span><span class="arraycolsep" style="width:0.5em;"></span><span class="arraycolsep" style="width:0.5em;"></span><span class="col-align-l"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:2.05em;"><span style="top:-4.21em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">1</span></span></span><span style="top:-3.01em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">0</span></span></span><span style="top:-1.81em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord mathnormal">ϵ</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:1.55em;"><span></span></span></span></span></span><span class="arraycolsep" style="width:0.5em;"></span></span></span><span class="mclose"><span class="delimsizing mult"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:2.05em;"><span style="top:-2.25em;"><span class="pstrut" style="height:3.155em;"></span><span class="delimsizinginner delim-size4"><span>⎦</span></span></span><span style="top:-3.397em;"><span class="pstrut" style="height:3.155em;"></span><span style="height:0.016em;width:0.6667em;"><svg xmlns="http://www.w3.org/2000/svg" width='0.6667em' height='0.016em' style='width:0.6667em' viewBox='0 0 666.67 16' preserveAspectRatio='xMinYMin'><path d='M263 0 H347 V16 H263z M263 0 H347 V16 H263z'/></svg></span></span><span style="top:-4.05em;"><span class="pstrut" style="height:3.155em;"></span><span class="delimsizinginner delim-size4"><span>⎤</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:1.55em;"><span></span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mpunct">,</span></span></span></span> where <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5782em;vertical-align:-0.0391em;"></span><span class="mord mathnormal">ϵ</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">∈</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.6889em;"></span><span class="mord mathbb">R</span></span></span></span>. Compute eigenvalues for the matrix <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8413em;"></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span></span></span></span> by hand. For which values of <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.4306em;"></span><span class="mord mathnormal">ϵ</span></span></span></span> the null-space of <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathnormal">A</span></span></span></span> is trivial? (c) Determine <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mopen">(</span><span class="mord mathnormal">A</span><span class="mclose">)</span></span></span></span> using matlab, when <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.4306em;"></span><span class="mord mathnormal">ϵ</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1.0085em;vertical-align:-0.1944em;"></span><span class="mord">1</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord">1</span><span class="mord"><span class="mord">0</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8141em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">−</span><span class="mord mtight">6</span></span></span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8141em;"></span><span class="mord">1</span><span class="mord"><span class="mord">0</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8141em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">−</span><span class="mord mtight">9</span></span></span></span></span></span></span></span></span></span></span></span>. Compute eigenvalues and corresponding eigenvectors for <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8413em;"></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span></span></span></span> numerically. Does Matlab agree with you on the dimension of <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mopen">(</span><span class="mord mathnormal">A</span><span class="mclose">)</span></span></span></span> for each value of <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.4306em;"></span><span class="mord mathnormal">ϵ</span></span></span></span> ? Include the script that you used and the computed eigenvalues and vectors to your solution. Hints: (a) The inclusion <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mopen">(</span><span class="mord mathnormal">A</span><span class="mclose">)</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">⊂</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1.2em;vertical-align:-0.35em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size1">(</span></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size1">)</span></span></span></span></span></span> can be easily proven. To prove that <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1.2em;vertical-align:-0.35em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size1">(</span></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size1">)</span></span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">⊂</span></span></span></span> <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mopen">(</span><span class="mord mathnormal">A</span><span class="mclose">)</span></span></span></span>, multiply <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8413em;"></span><span class="mord"><span class="mord mathnormal">A</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8413em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.13889em;">T</span></span></span></span></span></span></span></span></span><span class="mord mathnormal">A</span></span></span></span> from both sides with <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.4444em;"></span><span class="mord"><span class="mord"><span class="mord boldsymbol">x</span></span></span></span></span></span> and interpret the result as <span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1.0641em;vertical-align:-0.25em;"></span><span class="mord">∥</span><span class="mord mathnormal">A</span><span class="mord"><span class="mord"><span class="mord boldsymbol">x</span></span></span><span class="mord"><span class="mord">∥</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.8141em;"><span style="top:-2.4519em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">2</span></span></span></span><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">2</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.2481em;"><span></span></span></span></span></span></span></span></span></span>. (c) Try out he commands help eig and format long in Matlab.