Question

The figure below shows a waveform on a CRO screen,

Given that the y-gain control is set to 20V/cm and the time base set at 10ms/cm.
Calculate;

1. The peak voltage fed onto the y-plates.   
2. The periodic time of the wave.  
3. The frequency of the wave form.         
4. Explain what is meant by thermionic emission  
5. State two advantages of a CRO over conventional voltmeter.  

Answer 1

1. 20v/cm × 2cm =40
2. T=10ms/cm × 4cm =40ms
   T= ⁴⁰/₁₀₀₀s = 0.04s
3. f=¹/_T =¹/_0.04 =25HZ
4. Emission of electrons from a metal surface when heated
5.  
   1. Infinite resistance hence no current flows through 
   2. Can measure both ac and dc
   3. Record results instantaneously
   4. Can measure large voltages without damage