What colour wire is used for earthing or grounding?

What is the shape of the magnetic field lines around a circular current-carrying conductor?

From which of the following cases,will the induced current in the loop not be obtained?

Who first observed that a current-carrying wire experiences a force when placed in a strong magnetic field?

Name the rule used to find the direction of force on a current-carrying conductor placed in a magnetic field.

The flow of a current in a circular loop of a wire creates a magnetic field at its centre. How can the existence of this field be detected? State the rule which helps to predict the direction of this magnetic field.