Question

The instrument used to measure current is called
1. Wattmeter
2. Ohm meter
3. Energy meter
4. CRO

Answer 1

Correct Answer - Option 4 : CRO

• CRO is a very versatile instrument in the laboratory for measurement of voltage, current, frequency and phase angle of any electrical quantity.
• A Lissajous figure is a pattern which is displayed on the screen when sinusoidal signals are applied to both horizontal & vertical deflection plates of CRO.
• These are used to measure the frequency of the given signals and phase difference between the signals.
• From the shape of the Lissajous pattern displayed on the CRO screen information about relative phases of signals and the frequency ratio of signals can be determined.
• It is not used for precise measurement; it depends on the type of signals.
• If one frequency is an integral multiple (harmonic) of the other, the pattern will be steady. If not, the figure will not be stationary.