A coil having 500 square loops each of side 10 cm is placed normal to a magnetic field which increases at the rate of 1T s⁻¹. The induced e.m.f. is?

A. 0.1 V
B. 5.0 V
C. 0.5 V
D. 1.0 V

Respuesta :

Answer:

B. 5.0 V

Explanation:

The induced electromotive force (emf) in a coil is given by Faraday's law of electromagnetic induction, which states that the induced emf [tex](\( \varepsilon \))[/tex] is equal to the rate of change of magnetic flux [tex](\( \Phi \))[/tex] through the coil.

The formula for Faraday's law is:

[tex]\[ \varepsilon = -N \frac{\Delta \Phi}{\Delta t} \][/tex]

Where:

- [tex]\( \varepsilon \)[/tex]mf, is the induced emf

[tex]- \( N \)[/tex] is the number of turns (loops) in the coil,

[tex]- \( \Delta \Phi \)[/tex] is the change in magnetic flux,

[tex]- \( \Delta t \)[/tex] is the change in time.

The magnetic flux [tex](\( \Phi \))[/tex] is given by the product of the magnetic field (\( B \)), the area [tex](\( A \))[/tex] through which the magnetic field lines pass, and the cosine of the angle [tex](\( \theta \))[/tex] between the magnetic field lines and the normal to the area:

[tex]\[ \Phi = B \cdot A \cdot \cos(\theta) \][/tex]

In this case, the coil is placed normally to the magnetic field, so [tex]\( \theta = 0° \) and \( \cos(0°) = 1 \).[/tex] Therefore, the formula simplifies to:

[tex]\[ \Phi = B \cdot A \][/tex]

Given that:

[tex]- \( B = 1 \, \text{T} \) (the magnetic field increases at a rate of \( 1 \, \text{T/s} \)),[/tex]

- \( A = 500 \) square loops, each of side \( 10 \, \text{cm} \) (\( A = 500 \times (0.1 \, \text{m})^2 \)),

[tex]- \( \Delta t = 1 \, \text{s} \) (the change in time is \( 1 \, \text{s} \)).[/tex]

Now, substitute these values into the formula for induced emf:

[tex]\[ \varepsilon = -N \frac{\Delta \Phi}{\Delta t} \][/tex]

[tex]\[ \varepsilon = -500 \frac{(1 \, \text{T} \cdot 500 \times (0.1 \, \text{m})^2)}{1 \, \text{s}} \][/tex]

[tex]\[ \varepsilon = -500 \times (0.1)^2 \, \text{V} \][/tex]

[tex]\[ \varepsilon = -5 \times 10^{-3} \, \text{V} \][/tex]

The negative sign indicates the direction of the induced emf. However, since the question is asking for the magnitude, the answer is:

[tex]\[ \text{Induced emf} = 5 \times 10^{-3} \, \text{V} \][/tex]

So, the correct answer is:

[tex]\[ \text{B. } 5.0 \, \text{V} \][/tex]