Reading mechanism on optical discs.

Reading mechanism on optical discs.

• A. Reflected light indicates a 1; no reflection indicates 0
• B. The magnetic field encodes data
• C. Data is stored as pits and lands read by contact
• D. Light pulses indicate data

Answer: (A)

Reading optical discs works by shining a laser onto the disc surface and sensing how much light bounces back. The tiny pits and flat lands on the disc affect this reflection: information is carried by the pattern of reflected vs. non-reflected light as the disc spins under the laser. The best way to describe how the data is interpreted is that reflected light is detected as a 1, while a lack of reflection is treated as a 0. This reflects how the sensor converts changes in brightness into binary data, because a land generally reflects more light than a pit as the laser moves across the surface. Note that in practice there’s always some reflection, but the relative change between high (land) and low (pit) reflections encodes the information. The other options mix in magnetic storage concepts, imply physical contact reading, or vague “light pulses” ideas that don’t capture how pits and lands create the data through reflectivity.

Reading optical discs works by shining a laser onto the disc surface and sensing how much light bounces back. The tiny pits and flat lands on the disc affect this reflection: information is carried by the pattern of reflected vs. non-reflected light as the disc spins under the laser. The best way to describe how the data is interpreted is that reflected light is detected as a 1, while a lack of reflection is treated as a 0. This reflects how the sensor converts changes in brightness into binary data, because a land generally reflects more light than a pit as the laser moves across the surface. Note that in practice there’s always some reflection, but the relative change between high (land) and low (pit) reflections encodes the information. The other options mix in magnetic storage concepts, imply physical contact reading, or vague “light pulses” ideas that don’t capture how pits and lands create the data through reflectivity.