Zubeda made an electric circuit using a cell holder shown in figure, a switch and a bulb. When she put the switch in the 'ON' position, the bulb did not glow. Help Zubeda in identify the possible defects in the circuit.

It is important to put the cells in right series. The positive terminal of the first cell should be connected with negative terminal of the second cell. The switch should be closed properly and bulb should not be fused. If Zubeda will check these then the bulb will certainly glow.