Question

All the bulbs and cells used in the circuits are identical. If the switches are turned ON, in which of the following options will the bulb(s) be the dimmest?

• A.
  
• B.
  
• C.
• D.
  

Answer 1

The correct option is C

Among the given circuits, the circuit in which a single cell has been connected to two bulbs that are in series, will have the dimmest bulbs.
In a series circuit, the same amount of current flows through all the components placed in it. Therefore the bulb here is getting a power equal to half that of a single cell.

Two bulbs connected in parallel configuration to one cell is as bright as a bulb connected to a single cell.

Two bulbs connected in parallel configuration to two cell in parallel is as bright as a bulb connected to a single cell.

Lastly,
Two bulbs connected in parallel configuration to two cells in series is as bright as a bulb connected to two cells. The bulbs in this circuit are the brightest among all the circuits.