# Current in circuit (bulbs)

1. Jan 1, 2017

### ravsterphysics

2. Relevant equations
Power = VI

3. The attempt at a solution

Since lamp M breaks, lamp L gets more of the current so its brightness increases and lamp N's brightness stays the same because the current at point 2 is the same if the other lamp breaks or not, so N's brightness should not be affected.

So my answer is A but the correct answer is D?? What have I done wrong?

2. Jan 1, 2017

### ehild

The current through N will also change, as the resultant resistance changes when lamp M breaks.

3. Jan 1, 2017

### ravsterphysics

I get it now.

since the parallel combo is no more, resistance has increased across the circuit so less current for both, so N decreases but L increases since it has more current in resistance than in parallel. Thanks.

4. Jan 1, 2017

### ehild

It is correct, but can you derive what are the powers on the lamps in both cases, to prove your statement? The EMF of the battery is E and each lamp has resistance r.