(1)

The stream of electrons drawn by the toaster is 36.36 A.

$Given, P=4kW,V=110V$

We know that, $$\begin{gathered} Power=VI=110\times I \\ 4000=110\times I \\ I=36.36A \end{gathered}$$

(2)

Use of fuse is most important safety method protecting home appliances from overloading and short circuiting.

 (2)

Given,
I=6 A, L=40 cm=0.4 m, r=1.2 m, N=520

We know that,$B=\frac{{\mu }_{0}NI}{L}$

On substituting the values in above formula:

$$\begin{gathered} B=\frac{\left(4\pi \times {10}^{-7}\times 520\times 6\right)}{0.4} \\ =\frac{\left(4\times 3.14\times {10}^{-7}\times 520\times 6\right)}{0.4} \\ =97968\times {10}^{-7}=9.8\times {10}^{-3}T \end{gathered}$$

The magnetic field inside the solenoid is

$B=9.8\times {10}^{-3}T$

(2)

$$\begin{gathered} P=1kW=1000W,V=250V \\ Current, I=P/V \\ = 1000/250 = 4A \end{gathered}$$

Because current drawn is 4 A, a fuse of 13 A cannot be considered the most appropriate.

(4)

The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid because current flowing through the solenoid is saturated.

(4)

If the current is doubled in each wire the force will be 4F. This can be explained as follows:

We know that the force of repulsion per unit length between two wires carrying current in opposite direction is:

$\frac{F}{l}=\frac{{\mu }_0{i}_1{i}_2}{2\pi d}$

Thus, when both $i_1 and i_2$ are doubled, the force between them becomes four times.

(1)

When wires are connected in series, $R_s=R_1+R_2$

In parallel,

 $$\begin{gathered} R_p=\frac{R_1 R_2}{R_1+R_2} \\ : R_s>R_p \\ : H_2<H_1 [H\propto R] \end{gathered}$$

Then $H_{1 }> H_2$

(3)

Inside the solenoid, magnetic field lines are straight. This indicates strong magnetic field. Hence, magnetic field is uniform at all points inside the solenoid.

(3)

Magnetic lines of forces are closed continuous curves. They are nearer to each other at the point where magnetic field is strongest and far from each other where magnetic field is weak. At poles, magnetic lines of forces are nearest to each other because magnetic field is strongest at the pole.

No two magnetic lines of forces intersect with each other. At the point of intersection, the compass needle would point towards two directions, which is not possible.

They are continuous, forming closed loops without beginning or end, which start from the north pole and end at the south pole. Hence, statement (c), i.e., Magnetic lines of force are far away from each other at the poles is the incorrect statement.

(2)

The strength of the magnetic field at a point in the space surrounding the magnet is measured by number of lines crossing a given point.