WAEC SSCE - Physics - 1990 (Objective)

Question 1 Report

The diagram above represents a portion of a micrometer screw 20 gauge. What is its reading?

3.70mm

3.67mm

3.50mm

3.33mm

3.17mm

Answer Details

To determine the reading of the micrometer screw gauge, we need to add the main scale reading to the circular scale reading. From the image, we can see that the main scale reading is 3.0 mm, which is the distance shown between the left end of the sleeve and the central zero mark on the thimble. To find the circular scale reading, we count the number of divisions on the circular scale that line up with the main scale. We see that the 20th line on the circular scale is aligned with the main scale. Since each division on the circular scale represents 0.01 mm, we can calculate the circular scale reading as 20 x 0.01 mm = 0.20 mm. Therefore, the total reading is 3.0 mm + 0.20 mm = 3.20 mm. None of the answer options match our calculated value. The closest option is 3.17 mm.






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