Sources of Direct Current Quiz

Sources of Direct Current

• Direct current (DC) is a unidirectional flow of electric charge.
• Sources of DC include various types of cells and batteries.
• These sources create a potential difference that drives the flow of electrons.
• Different sources provide different levels of voltage and current.
• The source must maintain a consistent potential difference for a constant DC.

Kinds of Cells

• Primary cells are non-rechargeable. Once the chemical reactants are used up, the cell is spent.
  • Examples: zinc-carbon cells, alkaline cells.
• Secondary cells (batteries) are rechargeable. The chemical reactions are reversible and can be restored to their initial state.
  • Examples: lead-acid batteries, nickel-cadmium (NiCd) batteries, lithium-ion batteries
  • Rechargeable batteries store chemical energy and convert it to electrical energy. They have a longer lifespan than primary cells.

Electric Current As Rate of Flow of Electric Charge

• Electric current is the rate at which electric charge flows through a conductor.
• It is measured in amperes (A), where 1 ampere is equal to 1 coulomb of charge per second.
• Mathematically, current (I) = charge (Q) / time (t).
• Current represents the number of electrons flowing per unit time.

Direction of Current

• Conventional current direction is defined as the direction in which positive charge would flow.
  • Historically, positive charge was thought to be the carrier. This standard is still used.
• Electron flow is the actual movement of negatively charged electrons.
  • Electrons flow in the opposite direction to the conventional current.
  • The direction of electron flow is against the direction of conventional current.
• Both conventional and electron flow concepts are valid, and the choice depends on the context.