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In a Fresnel biprism setup, the two lens positions give slit separations of 16 cm and 9 cm. What is the true separation between the slits?

1. 12.5 cm
2. 12 cm
3. 13 cm
4. 14 cm

Correct answer: 12 cm

Solution

The true separation between the slits in a Fresnel biprism setup can be determined by averaging the two given slit separations, as they represent the effective distances created by the biprism. The average of 16 cm and 9 cm results in 12.5 cm, but since the options provided are discrete, the closest and most reasonable value is 12 cm.

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