Why don't we hav interference when two candles are placed close to each other and the intensity is seen at a distant scree? What happens if the candles are replaced by laser sources?

Why don't we have interference when two candles are placed close to each other and the intensity is seen at a distant screen? What happens if the candles are replaced by laser sources?

Why can't we obtain interference using two independent source of light?

Why don't we hear sounds when our ears are closed?

Why don't we hear sounds when our ears are closed?

Two polaroids are placed at 90^@ to each and the transmitted intensity is zero. What happens when one of them is rotated?

Two plane mirros are placed parallel to each other. A small candle is placed in between the two plane mirrors. The number of images of the candle are

No interference pattern is detected when two coherent sources are infinitely close to each other. Why?

No interference pattern is detected when two coherent sources are infinitely close to each other. Why?