Which of the following are true? Select all that apply. (1) In equilibrium, there is no net flow of mobile charged particles inside a conductor. (2) The electric field from an external charge cannot penetrate to the center of a block of iron. (3) The net electric field inside a block of aluminum is zero under all circumstances. (4) If the net electric field at a particular location inside a piece of metal is not zero, the metal is not in equilibrium. (5) The net electric field at any location inside a block of copper is zero if the copper block is in equilibrium.

In the equilibrium position, no flow of the charge occurs between two charged particles and the value of the electric field is zero.

The concept of the equilibrium position gives the correct statement.

Statement (2) is false as an external “electric field” can go through the conductor, and the induced charges cancel the external field. So, anelectric field from an external charge can penetrate the center of a block of iron.

Statement (1) is true because no net electric field is there during the equilibrium state, and the mobile charges cannot flow as no forces are acting.

Statement (3) is true as the forces get induced on the mobile charges, and the charges flow freely as the conductor is not at equilibrium due to the net electric field.

Statement (4) is correct as the electric field inside a conductor only be zero if it is in equilibrium. Moreover, if the conductor is not in equilibrium, the field is not zero. So,If the net electric field at a particular location inside a piece of metal is not zero, the metal is not in equilibrium.

Statement (5) is correct as, during the equilibrium state, the net electric field is zero inside a conductor and the copper block is in the equilibrium state.

Thus, statements (1), (3), (4), and (5) are true.