Define one ampere.

What will happen to the resistance of the circuit,if the current through it is doubled?

Study the following circuit and answer the following questions:
$(i)$ State the type of combination of the two resistors in the circuit.
$(ii)$ How much current would flow through:
$(a)$ $10 \, \Omega$ resistor and
$(b)$ $15 \, \Omega$ resistor?
$(iii)$ What would be the ammeter reading?

There is a frill of $20$ bulbs connected in series in a room. One bulb gets fused. The remaining $19$ are again joined in series and connected to the same supply. Will the light increase or decrease in the room?

How many watt-seconds are equal to $1$ unit of electrical energy?

$(a)$ Derive an expression to find the equivalent resistance of three resistors connected in series. Also,draw the schematic diagram of the circuit.
$(b)$ Find the equivalent resistance of the following circuit.