A rectangular metallic loop is moving out of a uniform magnetic field region to a field free region with a constant speed. When the loop is partially inside the magnate field, the plot of magnitude of induced emf $\left(\epsilon \right)$ with time (t) is given by

Faraday's Law states that the induced emf is given by:

$$\varepsilon = -\frac{d\Phi_B}{dt}$$

where:

$\Phi_B = B A$ is the magnetic flux,

$A = l x$ is the area inside the field ($l$ is the width of the loop and $x$ is the length inside the field),

$B$ is the magnetic field strength.

Since the loop is moving with a constant velocity $v$:

$$x = x_0 - v t$$

The flux changes as:

$$\Phi_B = B l x$$

Differentiating:

$$\varepsilon = B l \frac{dx}{dt}$$

Since $dx/dt = v$, we get:

$$\varepsilon = B l v$$

This means the induced emf is constant while the loop is exiting the field.