#CATHODE RAY EXPERIMENT DIAGRAM VERIFICATION#

It gives accurate voltages than a moving coil voltmeter.ī)Ě CRO can measure both d.c and a.c voltage. Suppose they are displayed simultaneously by applying them to the two Y-input.Ĭomparison o CRO with a moving coil Voltmeter.Ī) The CRO has very high impedence. If x1 and x2 are distances occupied by one cycle for two waveform, then the ratio, where T1 and T2 are the periodic times of the two waves respectively.ĭ) Measurement of phase difference using a double beam CRO: the two waveforms to be compared have the same frequency. This is proportional to twice to the amplitude or peak voltage, V0.Ĭ)Ĝomparison of frequencies of two waveforms: suppose two waveforms of frequency f1 and frequency f2 appear on the screen of the CRO having two Y-inputs or are displayed at a time on the CRO with a single Y-input. This can be centred and its length measured.

If the time base is switched off, a vertical line is obtained on the screen. For an a.c signal applied across the Y- plates and time base on the X-plates, one observes the waveform shown below Ī)ĝisplaying of waveforms: the amplitude and frequency of the wave can be obtained.ī) Measurement of Voltage: An unknown voltage is applied across the Y- plates. To observe the wave form of the applied voltage to Y-plates, the frequency of the time base is synchronised with the frequency of the signal applied to Y-plates. When no signal is applied to the Y- plates, the voltage V, causes the electron beam to sweep horizontally to and fro on the screen as shown. Hence the time taken by return of the electron beam to the original position at the other end of the screen is small. The time taken for p.d to fall from A to B known as the fly back time, is extremely small compared to the time taken to rise from O to A. The saw tooth voltage which sweeps the electron beam from left to right at a constant speed. The time base has a saw-tooth waveform and is generated by a special in the CRO. To observe the waveform of the a.c signal applied to the Y-plates, a special voltage called time base connected to the X- plates. If the X- plates are shunted and an a.c is applied to Y-plates, the electron beam is drawn into a vertical line. The electron spot would be deflected vertically. Suppose the X- plates were shunted and a d.c voltage was applied to the Y- plates. Power supply:-This is a smoothened rectified a.c, fed through a chain of resistors. Graphite Coating:- Enables light to be seen only on the screen as the graphite coating absorbs the electron’s kinetic energy. It enters light when struck by electron beam. Y-Plates, Y1 and Y2:- These are horizontal pates but deflect the beam vertically when a p.d is applied across them.įluorescent Screen:- This is coated with fluorescent material such as Zns. X-plates, X1 and X2:-these are vertical plates but they deflect the beam horizontally when a p.d is applied across them. The anode accelerates the electron beam along the tube and also focuses the electron beam by means of the potential divider R2. (ii) it refocuses the electron beam so that the beam emerges from the hole as a narrow beam.Īnodes A1 and A2:- These are held at a positive potential relative to the cathode. It is held at variable negative potential relative to the cathode by means of the potential divider R1, The grid serves two purposes namely: (i) as a brightness control The grid, G:- it consists of a hollow metal cylinder with a small hole at the end. Indirectly heated Cathode, C :-Emits electrons by thermionic emission. Shadow of the Maltese cross cast on the florescent screenĮvacuated Glass tube:- the glass tube evacuated to prevent scattering of the electron beam when electrons collide with air molecules. If an opaque object (Maltese cross) is placed in the path of the cathode rays, a sharp shadow of the Maltese cross is cast on the screen.

#CATHODE RAY EXPERIMENT DIAGRAM VERIFICATION#

Verification that electrons travel in a straight line They are electrons moving with high speeds. When cathode rays are stopped by heavy metals, x-rays are emitted. They cause fluorescence in certain materials. They are deflected by both magnetic and electric fields (this proves that they carry a charge) This shows that electrons posses momentum and therefore have mass.

When the cathode rays hit the florescent screen, the screen glows. The tube is evacuated to avoid electrons interacting with any particle before they reach the screen. The thermionic emission is the process whereby metal surfaces emit electrons when heated. The electrons are produced at the cathode by thermionic emission and are accelerated towards the screen by the anode which is connected to the terminal of the extra high tension battery.

Cathode ray experiment diagram