PREPARED BY: DR. HEBA MOHAMED FAHMYFOR FIRST YEAR BIOPHYSICS STUDENTS

Cathode ray tube ( oscilloscope)

Aim of the experiment

1. Determination of the amplitude, the periodic time and the frequency of the given waves (sine, triangle and square).

2. Sketch the given waves.

Sine

Square

triangle

What is a cathode ray tube ?

The cathode ray tube is a vacuum tube containing a gas at a pressure of 0.01 mmHg.

The electron gun (cathode): emits a beam of electrons

The deflecting system: may consist of two pairs of metal plates which produce two electric fields or of two pairs of coils which produce two magnetic fields. These fields deflect the beam of electrons.

Carbon emulsion: is connected to the cathode for carrying electrons back to the cathode without the accumulation of a charge on the screen.

The cathode ray oscilloscope:

is a cathode ray tube having a deflecting system consisting of two pairs of metal plates (x1, x2) and (y1, y2) which produce two electric fields perpendicular to each other and at the same time perpendicular to the direction of motion of electrons.

Vertical plates (x1 and x2) are connected to the sweep voltage that produces saw tooth voltage

Horizontal plates (y1 and y2) are connected to the investigated voltage

Frequency (F): It is the number of complete cycles per unit time.

Periodic time (T): It is the time taken to complete one cycle of the wave.

Amplitude (A): It is the maximum displacement of the wave.

The practical part

Ch1 or Ch2 ????

X= ? Y= ?

X= ? Y= ?

X= ? Y= ?

Time / DivVolt / Div

Why to use the X and Y bottons ??

Type of the wave

Y Volt / div

Vpp(volt)

A= Vpp / 2(volt)

X Time / div

Periodic time (sec)

Frequency = 1 / Periodic

time (Hz)

Sine

Triangle

square

Results

ANY QUESTION

S ?