Physics, 10.10.2019 21:30 janaemartinez42

Atechnician wearing a brass bracelet enclosing area 0.00500 m2 places her hand in a solenoid whose magnetic field is 2.70 t directed perpendicular to the plane of the bracelet. the electrical resistance around the circumference of the bracelet is 0.0200 . an unexpected power failure causes the field to drop to 0.81 t in a time of 19.0 ms. (a) find the current induced in the bracelet. a (b) find the power delivered to the bracelet. (note: as this problem implies, you should not wear any metal objects when working in regions of strong magnetic fields.) w

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Answer from: sonykorah7279

(a) 25 A

The induced emf in the circuit is given by

$\epsilon = -\frac{\Delta \Phi}{\Delta t}$

where

$\Delta Phi$ is the variation of magnetic flux through the bracelet

$\Delta t = 19.0 ms =0.019 s$ is the time interval

The variation of magnetic flux is

$\Delta \Phi = A \Delta B$

where

A=0.005 m^2 is the area enclosed by the bracelet

$\Delta B=0.81 T-2.70 T=-1.89 T$ is the change of magnetic field strength

So we find

$\Delta \Phi = (0.005 m^2)(-1.89 T)=-9.45\cdot 10^{-3} Wb$

And so the induced emf is

$\epsilon = -\frac{-9.45\cdot 10^{-3} Wb}{0.019 s}=0.50 V$

Since the resistance of the bracelet is

$R=0.02\Omega$

the induced current is

$I=\frac{V}{R}=\frac{0.50 V}{0.02 \Omega}=25 A$

(b) 12.5 W

The power delivered to the bracelet is given by

P=V I

where we have

I = 25 A is the current

V = 0.50 V is the emf induced in the bracelet

Substituting numbers, we find

P=(0.50 V)(25 A)=12.5 W

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

Answer from: Quest

technology is the application of the knowledge gained by science.

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Atechnician wearing a brass bracelet enclosing area 0.00500 m2 places her hand in a solenoid whose m...

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