For the circuit shown, a shorting wire of negligible resistance is added to the circuit between points A and B. When this shorting wire is added, bulb-3 goes out. Which bulbs (all identical) in the circuit brighten?
only bulb 2
only bulbs 1 and 4
only bulbs 2 and 4
only bulb 4
The correct option is B only bulbs 1 and 4 l1 and l4 increases. (effective resistance in their respective branches will reduce.