What is the safety method used for protecting home appliances short circuiting or overloading in domestic electric fittings?

State the rule which gives the direction of force acting on a current-carrying conductor kept in a magnetic field.

What does the degree of closeness of the field lines represent?

A charged particle enters at right angles into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field?

Why cannot two magnetic field lines cross each other?