Answer
a. Electrical current - Electrical current is the rate of the flow of charge. It is the ratio of the number of electrons, flowing in a specific material and the time took to flow. If I is abbreviated as the current, and Q is the charge, flowing in the material, and t is the time taken, then the relation between them is as follows -
I = \frac{Q}{t}
Based on the type, the current is of two types - Alternating current (AC), and Direct current (DC). Its unit is Ampere.
b. Voltage - The voltage is the work done in taking a unit charge from infinite at a point in the circuit. It is abbreviated as V. If V is the voltage at a point, and Q is the charge, then, the relation between them is as follows -
Voltage (V) = \frac{Work done in moving the charge from infinite at a point}{Q}
c. An open switch - Removing the connection from the circuit is known as opening the switch. It stops the flow of current.
d. A closed switch - Connecting the closed path in the circuit is known as closing the switch. It allows the flow of current.
e. Direct current - Current, which doesn't change with time is known as the direct current. It is constant over time. For example - I = 10 Amperes. It is abbreviated as DC.
f. Alternating Current - Current, which is not constant over time. It changes periodically with respect to time. For example - I = sin10t Amperes. It is abbreviated as AC
