Which of the following is NOT an angular measuring instrument?

Explanation

Explanation: Angular measurement involves the measurement of angles of tapers and similar surfaces. Examples: Bevel protector Sine Bar Spirit level Clinometer Autocollimators Bevel protector: Bevel protector is used for measuring the angles between two faces of components. It has a base plate or stock whose surface has a high degree of flatness and surface finish. The stock is placed on the workpiece whose angle is to be measured. It is normally used as a reference base for measuring angles. An adjustable blade attached to a circular dial is made to coincide with the angular surface. It can be swiveled to the required angle and can be locked. Sine bar A sine bar is a precision measuring instrument for checking and setting of angles. The size of a sine bar is specified by its length. The l ength of the sine bar is the distance between the centers of the rollers. A sine bar is used to measure angles based on the sine principle. Its upper surface forms the hypotenuse of a triangle formed by a steel bar terminating in a cylinder near each end. When one of the cylinders, called a roller, is resting on a flat surface, the bar can be set at any desired angle by simply raising the second cylinder. The required angle is obtained when the difference in height between the two rollers is equal to the sine of the angle multiplied by the distance between the centers of the rollers. sin θ = ​L h Autocollimator An autocollimator is an optical instrument that is used to measure small angles with very high sensitivity. The autocollimator has a wide variety of applications including precision alignment, detection of angular movement, verification of angle standards, and angular monitoring over long periods. An autocollimator is essentially an infinity telescope and a collimator combined into one instrument. Micrometer A micrometer is a precision instrument used to measure a job, generally within an accuracy of 0.01 mm. Micrometers used to take the outside measurements are known as outside micrometers.