Screw Gauge Video Lecture - Physics for JEE Main & Advanced

Ans. A screw gauge, also known as a micrometer, is a precision instrument used to measure small distances or thicknesses with high accuracy. It consists of a U-shaped frame, a spindle, and a thimble. The spindle has a screw thread and moves through the frame when the thimble is rotated. By measuring the number of rotations and the pitch of the screw, the distance can be calculated.

Ans. The main parts of a screw gauge include the U-shaped frame, the spindle, the thimble, and the screw. The U-shaped frame holds the spindle and thimble in place. The spindle has a screw thread that moves through the frame. The thimble is rotated to move the spindle and measure the distance. The screw allows precise adjustments and measurements.

Ans. The least count of a screw gauge is calculated by dividing the pitch of the screw by the number of divisions on the circular scale. The pitch is the distance moved by the spindle for one complete rotation of the thimble. The circular scale has equally spaced divisions that help in measuring the rotations. By dividing the pitch by the number of divisions, we get the smallest distance that can be measured using the screw gauge.

Ans. Zero error in a screw gauge refers to the error that occurs when the zero mark on the thimble does not align perfectly with the zero mark on the sleeve. It can be positive or negative, depending on whether the zero mark is above or below the reference line. To obtain accurate measurements, the zero error must be taken into account and corrected by adding or subtracting it from the measured value.

Ans. The accuracy of a screw gauge can be improved by taking the following measures: 1. Ensuring proper alignment: The frame, spindle, and thimble should be properly aligned to avoid any misalignment that could affect the measurements. 2. Zero error correction: The zero error should be determined and corrected before taking any measurements. This helps in obtaining accurate readings. 3. Multiple measurements: Taking multiple measurements and calculating the average helps in reducing random errors and increasing the accuracy. 4. Appropriate technique: Proper technique, such as applying uniform pressure and avoiding parallax errors, should be followed while using the screw gauge. 5. Regular calibration: Regular calibration and maintenance of the screw gauge ensure its accuracy and reliability over time.