Crookes tube :  

1.It  is composed of the following parts:

glass envelope, conduction track support, paddle Wheel, circular plate, support, etc.

 Accessory

1.Low voltage D.C. source 10-12V.

2. High voltage induction coil: Spark distance 50-80mm.

3. Voltage adjustable transformer: A.C. 220V±10V.

4. High voltage D.C. source: 250V-300v.

5. U-shape magnet: pole distance 50-70mm.

6. Connecting wires and with crocodile clips.

Demonstration Environment Condition

1. Relative humidity is not greater than 80%.

2. Temperature: -10-40.

The cathode ray tubes manufactured is aimed for physics teachers as a demonstration bit. The demonstration bit is consisted of four sets, namely J2453, J2454, J2455 and J2456.

Use

1. J2453—for demonstrating the phenomenon that cathode ray travels in a straight line and deflects in a magnetic field, hence indicates that cathode ray is formed by charge Particles emitted by the cathode.
2. J2454“+”—for demonstrating. Cathode ray travels in a straight line and can be blocked by metallic objects.
3. J2455—for demonstrating mechanical motion of object by cathode ray, hence indicates that cathode ray has momentum and energy.
4. J2456—for demonstrating the deflection of cathode ray in an electric field, hence indicates that cathode ray consists of negatively charged Particles (that is electron current).

Structure

1. J2453 is composed of the following parts: glass envelope,

1. grid plate, fluorescent screen, cathode, anode, support, etc.
2. J2454 “+”is composed of the following parts: glass envelope, croshape metallic plate, cathode, anode, support, etc.
3. J2455 is composed of the following parts: glass envelope, conduction track support, paddle Wheel, circular plate, support, etc.
4. J2456 is composed of the following parts: glass envelope, anode, support, etc.

Accessory

1. Low voltage D.C. source 10-12V.
2. High voltage induction coil: Spark distance 50-80mm.
3. Voltage adjustable transformer: A.C. 220V±10V.
4. High voltage D.C. source: 250V-300v.
5. U-shape magnet: pole distance 50-70mm.
6. Connecting wires and with crocodile clips.

Demonstration Environment Condition

1. Relative humidity is not greater than 80%.
2. Temperature: -10℃-40℃.

Method of Demonstration

The connection method for the four types of c.r.t. is shown in fig. (1) to fig. (4). Each c.r.t. has two poles, A₁ and A_2. A₁ is connected to the “+” terminal of the induction coil, while A₂ is connected to the “-” terminal. When the supply is connected, cathode ray will emit from the cathode A_2.  If the polarity of A₁ and A₂ is reversed, no emission of cathode ray occurs (except for c.r.t. of J2455) and the polarity switch of the induction coil should be changed by appropriately.

1. When demonstrating the magnetic effect of cathode ray, A₁ will emit cathode ray and a beam trace will appear on the fluorescent screen, indicating that cathode ray travels in a straight line. If a transverse magnetic field is added (with the unshaped magnetic sides on the central portion of the envelope). The path traced by the cathode ray will be deflected, showing that the ray is composed of charged Parked particles.

N.B. The ray emitted by A₂ is electron current. Its direction of flow is opposite to that of   current, according to the direction of the magnetic field, the ray deflecting direction can be found.

2.  When demonstrating cathode ray travels in straight line, it is better to do in a dark room. Ray emitted by A₁ will from a “+”shadow in fluorescent screen. Outside the shadow is bright yellowish-green fluorescent light. This indicates that cathode ray travels, in a straight line with little penetration into metallic plate.

3.  When demonstrating the mechanical effect of cathode ray, the circular plate emits cathode ray, which strikes the paddle wheel on which fluorescent materials are coated. The paddle wheel will glow and rotate in the direction of motion of the cathode ray. If the polarity switch of the induction coil is reversed cathode ray will be generated in the opposite direction (both circular plates can emit cathode ray), the direction of rotation of paddle ray consists of a beam of particles, with momentum and energy and these can be transferred to objects when illuminated.

4.  Before demonstrating the static effect of cathode ray, first connect the low voltage supply and switched the polarity switch of the induction coil so that cathode ray is generated and a beam trace appears on the fluorescent screen. Then the high voltage supply is turned on. The beam on the screen will deflect to the plate side with high voltage, if the voltage output of the transformer is varied (that is, high D.C.voltage variation causes the electron field in entity to vary). The degree of deflection of the beam trace will also varies showing that cathode ray consists of negatively charged particles; these negatively charged particles are called electrons. N.B. If the D.C. applied to the electric poles B₁ and B₂ is higher, the more stable will be the deflector of the cathode. Conversely, the beam trace tends to be unstable and flicker.

Avoid applying too high D.C. voltage (not greater than 400V); other wiseacre striking occurs between the parallel electric plates. If here is no voltage adjustable transformer, beam trace deflection cannot be seen.

Experiment show that if the transformer and the high D.C. voltage are dis- connected, and with one pole (B₁ or B₂) connected to ground and the other floating, a static field is formed by auto-boosting, beam deflection will be seen.

Precautions

1. Handle the glass envelope carefully to avoid gas leakage male-functioning.
2. When connect electric poles, avoiding inserting too much force.
3. Before demonstration, make sure that wire connections and voltages are correct.
4. To avoid soldering of the fluorescent screen, its ability to emit light and strongly absorbing gas by the glass envelope due to long duration cathode ray impaction, do not leave the c.r.t. on voltage connection for long duration.
5. Apparatus should be securely placed in airy and dry place, avoid shaking and humidity. To enhance our product quality, we are pleased that customers make contact with us:

1) To give your view on problems arises in using the product.

2) To give suggestion on furthers improvement of product quality and other problems.