Which of these magnets has the strongest magnetic field?

Label the north pole and south pole of the electromagnet in the diagram.

Electrical devices often have an ampere marking to indicate the strength of electric current required for it to work.

Which wire should be connected to the negative terminal of a socket?

The digram below shows the magnetic field lines due to a current in a straight conductor.

Something was done to the current because of which the magnetic field lines changed  as shown below.

What was done to the current?

A stationary metal coil is placed in a magnetic field. The strength of the magnetic field varies with time as shown in the graph below.

In which of the time interval(s) is a current induced in the coil?

A small bar magnet is dropped vertically from rest into a long coil of wire, and it leaves from the other end as shown in the diagram below.

Compare the magnitude and direction of the induced current in the coil when the magnet enters the coil with the induced current in the coil when it leaves the coil.

a) In the circuit below, in case of an overload, will the fuse protect the electric oven from damage? Justify your answer.

b) If the oven has a rating of $13 \mathrm{A}$, what should be the minimum rating of the fuse?