If I showed you this detector, you would be likely to think to begin with that the way to make the detector go would be to put a block on top of the detector.
यदि मैं आपको ये डिटेक्टर दिखाऊँ, तो शायद आप सोचें कि इस डिटेक्टर को चालू करने के लिये इस के ऊपर एक ब्लाक रखना होगा।