Stroboscope is a non-contact type frequency instrument.

Explanation:

Stroboscope is a device used for measuring and analyzing rotating or vibrating objects. It is commonly used in industries for machine maintenance, quality control, and motion analysis. Stroboscope works by using high-intensity light flashes at regular intervals to freeze or slow down the motion of the object being observed. This allows for detailed analysis of the object's motion or vibration.

- Non-contact type frequency instrument: Stroboscope is a non-contact type instrument because it does not require physical contact with the object being observed. It uses light flashes to capture the object's motion, making it a non-intrusive method of measurement. This is particularly useful when dealing with delicate or sensitive objects where physical contact may cause damage or alter the object's behavior.

- Measurement of frequency: Stroboscope is primarily used for measuring the frequency of rotating or vibrating objects. It does this by adjusting the frequency of the light flashes to match the frequency of the object's motion. By adjusting the flash frequency, the stroboscope can make the object appear stationary or moving in slow motion. The frequency of the light flashes corresponds to the frequency of the object's motion, allowing for accurate frequency measurement.

- Limitations on frequency measurement: The statement that stroboscope can measure frequency up to 5 Hz is not correct. Stroboscopes are capable of measuring frequencies much higher than 5 Hz. They can typically measure frequencies ranging from a few Hz to several thousand Hz. The exact frequency range depends on the specific model and capabilities of the stroboscope.

- Use of electromagnetic radiations: The statement that stroboscope uses electromagnetic radiations to measure frequency is not correct. Stroboscope uses high-intensity light flashes, typically produced by xenon or LED lamps, to capture the motion of the object being observed. These light flashes are not considered electromagnetic radiations in the traditional sense. They are simply intense bursts of light used for visual observation and analysis.

In conclusion, stroboscope is a non-contact type frequency instrument that uses high-intensity light flashes to measure the frequency of rotating or vibrating objects. It does not use electromagnetic radiations for frequency measurement, and it is capable of measuring frequencies higher than 5 Hz.