A circular loop of wire with radius r=0.0250 m and resistance r=0.390 ohms is in a region of spatially uniform magnetic field. the magnetic field is directed into the plane. at t=0, b=0. the magnetic field then begins increasing, with b(t)=(0.380t/s^3)t^3. what is the current in the loop (magnitude and direction) at the instant when b=1.33 t.

Respuesta :

Finti

Answer:

0.0133 A

Explanation:

The time at which B=1.33 T is given by  

1.33 = 0.38*t^3  

t = (1.33/0.38)^(1/3) = 1.52 s  

Using Faraday's Law, we have  

emf = - dΦ/dt = - A dB/dt = - A d/dt ( 0.380 t^3 )  

Area A = pi * r² = 3.141 *(0.025 *0.025) = 0.00196 m²

emf = - A*(3*0.38)*t^2  

thus, the emf at t=1.52 s is  

emf = - 0.00196*(3*0.38)*(1.52)^2 = -0.0052 V  

if the resistance is 0.390 ohms, then the current is given by  

I = V/R = 0.0052/0.390 = 0.0133 A

The current in the loop (magnitude and direction) at the instant when b = 1.33 t is; I = 0.0133 A and flowing in the opposite direction

We are given;

Radius of loop; r = 0.025 m

Resistance; R = 0.390 Ω

b(t) = 0.38t³ T/s³

Now, we are given the instance when B = 1.33 T. Thus, time at this magnitude of magnetic field gives;

1.33 = 0.38t³  

t³ = 1.33/0.38

t = ∛3.5

t = 1.52 s

From faraday's law, the EMF is expressed as;

emf = -A(dB/dt)

Now, we have

b(t) = 0.38t³ T/s³

Thus;

dB/dT = 3(0.38t²)

Area is; A = πr²

A = π(0.025²)

A = 0.00196 m²  

Plugging the relevant values into the emf equation gives us;

emf = 0.00196 × (3 × 0.38) × (1.52)²

emf = -0.0052 V  

Formula for current here is;

I = V/R

Where V is emf or voltage and R is resistance. Thus;

I = -0.0052/0.390

I = -0.0133 A

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