To practice Problem-Solving Strategy 27.2 Motion in Magnetic Fields. An electron inside of a television tube moves with a speed of 2.74×107 m/s . It encounters a region with a uniform magnetic field oriented perpendicular to its trajectory. The electron begins to move along a circular arc of radius 0.190 m . What is the magnitude of the magnetic field?Part CCalculate the magnitude F of the force exerted on the electron by a magnetic field of magnitude 8.21×10−4 T oriented as described in the problem introduction.Express your answer in newtons.

Respuesta :

Answer:

The magnetic field is  [tex]B = 8.21 *10^{-4} \ T[/tex]

The force is  [tex]F= 3.599 *10^{-15} \ N[/tex]

Explanation:

From the question we are told that

   The speed of the electron is [tex]v = 2.74 *10^{7} \ m/s[/tex]

    The radius of the circular trajectory is [tex]r = 0.190 \ m[/tex]

Generally the magnetic force acting on the electron is equal to the centripetal  acting on the the electron , this is is mathematically represented as

          [tex]F_B = F_C[/tex]

Here  [tex]F_B[/tex] is the magnetic force that will cause the electron to move in a circular path  which is mathematically represented as

        [tex]F_B = q * v * B sin(90)[/tex]

       [tex]F_B = q * v * B[/tex]

while  [tex]F_C[/tex] is the centripetal  force which is mathematically represented as

      [tex]F_C = \frac{m v^2}{r}[/tex]

=>    [tex]q * v * B = \frac{m v^2}{r}[/tex]

=>  [tex]B = \frac{m * v}{ q r }[/tex]

Here q  is the charge on an electro with value  [tex]q= 1.60 *10^{-19 } \ C[/tex]

   and  m  is the mass of electron with value  [tex]m = 9.11 *10^{-31} \ kg[/tex]

So

      [tex]B = \frac{9.11 *10^{-31} * 2.74 *10^{7}}{ 1.60 *10^{-19} * 0.190 }[/tex]

=>    [tex]B = 8.21 *10^{-4} \ T[/tex]

Generally when the magnetic field is [tex]B = 8.21 *10^{-4} \ T[/tex] the magnetic force is  

     [tex]F= q * B * v[/tex]

=>  [tex]F= 1.60 *10^{-19} * 8.21 *10^{-4} * 2.74 *10^{7}[/tex]

=>  [tex]F= 3.599 *10^{-15} \ N[/tex]

     

(a) The magnetic field will be B=8.21*10^-4 T

(b) The force is equal to F=3.599*10^-15 N

What is magnetic field?

The magnetic filed is the influence of the magnetic force acts on a charged particle. The magnetic fields are generally generated by the flow of the currents.

From the question, it is given that

The speed of the electron is v=2.74*10^7 m/s

The radius of the circular trajectory is r=0.190 m

Generally the magnetic force acting on the electron is equal to the centripetal  acting on the the electron , this is is mathematically represented as

[tex]F_B=F_C[/tex]

         

Here  [tex]F_B[/tex]  is the magnetic force that will cause the electron to move in a circular path  which is mathematically represented as

[tex]F_B=q\times v\times Bsin(90)[/tex]

[tex]F_B=q\times v\times B[/tex]        

while [tex]F_C[/tex]  is the centripetal  force, which is mathematically represented as

[tex]F_C=\dfrac{mv^2}{r}[/tex]      

[tex]q\times v\times B=\dfrac{mv^2}{r}[/tex]

[tex]B=\dfrac{m\times v}{qr}[/tex]

Here q  is the charge on an electron with value  [tex]q=1.60\times 10^{-19} C[/tex]

and  m  is the mass of electron with value  [tex]m=9.11\times 10^{-31} kg[/tex]

So

[tex]B= \dfrac{9.11\times 10^{-11}\times 2.74\times 10^7}{1.60\times 10^{-19}\times 0.190}[/tex]      

[tex]B=8.21\times 10^{-4} \ T[/tex]

Generally when the magnetic field is  the magnetic force is  

[tex]F=q\times v\times B[/tex]

   

[tex]F=1.60\times 10^{-19}\times 8.21\times 10^{-4}\times 2.74\times 10^7[/tex]

[tex]F=3.599\times 10^{-15}\ N[/tex]

Thus the magnetic field will be B=8.21*10^-4 T and the force is equal to F=3.599*10^-15 N

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