engineering recuitment GATE IN Test Series 2023-24 Mock Test Sensors and Industrial Instrumentation Measurement of Speed
A disc mounted on the shaft of a machine has 15 patter points. The number of flashes projected on the disc by a stroboscope is 7200 in a minute, which of the following is/are true?
1
If the disc appears stationary, the speed of the machine is 480 rpm.
2
If the disc appears to move forward in the direction of rotation at 20 rpm, the speed of the machine is 460 rpm.
3
If the disc appears to move backward in the opposite direction of rotation at 20 rpm, the speed of the machine is 460 rpm.
4
If the disc appears to move forward in the direction of rotation at 20 rpm, the speed of the machine is 500 rpm.