A single loop of wire with an area of [tex]$9.06 \times 10^{-2} m^2$[/tex] is in a uniform magnetic field that has an initial value of [tex]$3.68 \, \text{T}$[/tex]. The field is perpendicular to the plane of the loop and is decreasing at a constant rate of [tex][tex]$0.196 \, \text{T/s}$[/tex][/tex].



Answer :

Certainly! Let's solve the problem step-by-step, detailing the calculations and concepts involved.

### Given Data:
1. Area of the loop, [tex]\( A \)[/tex]: [tex]\( 9.06 \times 10^{-2} \ \text{m}^2 \)[/tex]
2. Initial magnetic field, [tex]\( B_i \)[/tex]: [tex]\( 3.68 \ \text{T} \)[/tex]
3. Rate at which the magnetic field is decreasing, [tex]\( \frac{dB}{dt} \)[/tex]: [tex]\( -0.196 \ \text{T/s} \)[/tex]

### Find:
The induced electromotive force (emf) in the loop.

### Concepts and Formulae:
Faraday's Law of Induction states that the induced emf in a loop is given by:
[tex]\[ \text{emf} = - \frac{d\Phi}{dt} \][/tex]
where [tex]\( \Phi \)[/tex] is the magnetic flux. Magnetic flux [tex]\( \Phi \)[/tex] through a single loop is defined as:
[tex]\[ \Phi = B \cdot A \][/tex]
Since the magnetic field [tex]\( B \)[/tex] is perpendicular to the area [tex]\( A \)[/tex], the flux simplifies to:
[tex]\[ \Phi = B \cdot A \][/tex]

When the magnetic field is changing with time, the change in magnetic flux can be expressed as:
[tex]\[ \frac{d\Phi}{dt} = A \cdot \frac{dB}{dt} \][/tex]
So, the induced emf becomes:
[tex]\[ \text{emf} = - A \cdot \frac{dB}{dt} \][/tex]

### Step-by-Step Solution:
1. Identify the area of the loop:
[tex]\[ A = 9.06 \times 10^{-2} \ \text{m}^2 \][/tex]

2. Identify the rate of change of the magnetic field:
[tex]\[ \frac{dB}{dt} = -0.196 \ \text{T/s} \ (\text{the field is decreasing, hence the negative sign}) \][/tex]

3. Substitute the known values into the formula:
[tex]\[ \text{emf} = - A \cdot \frac{dB}{dt} \][/tex]

4. Calculate the induced emf:
[tex]\[ \text{emf} = - (9.06 \times 10^{-2} \ \text{m}^2) \cdot (-0.196 \ \text{T/s}) \][/tex]
[tex]\[ \text{emf} = (9.06 \times 10^{-2}) \times 0.196 \ \text{V} \][/tex]
[tex]\[ \text{emf} = 0.0177576 \ \text{V} \][/tex]

Therefore, the induced electromotive force (emf) in the loop is approximately [tex]\( -0.0177576 \ \text{V} \)[/tex]. The negative sign indicates the direction of the induced emf as per Lenz's Law, which states that the induced emf will act in such a way as to oppose the change in magnetic flux.