Page 186 - Physics Form 5 KSSM_Neat

Effects of Electric Field and Magnetic Field on Cathode Rays
Cathode rays are beams of electrons moving at high speed in a vacuum. The characteristics
of cathode rays can be studied using a deflection tube and a Maltese cross tube. Carry out
Activity 5.2 and Activity 5.3 to study the effects of electric field and magnetic field on the
direction of cathode rays.

Apparatus: Deflection tube, 6 V power supply, E.H.T. power supply and connecting wiresYSIA
Teacher’s demonstration
Activity
5.2
KEMENTERIAN PENDIDIKAN MALA
Aim: To study the effects of an electric field on cathode rays using a deflection tube

Instructions:
1. Set up the apparatus as shown in Figure 5.2.

Deflection
Cathode Anode plate S 3
S Vacuum
1
+ + +
6 V power E.H.T. power
supply supply
– – –
S
2
– +
Fluorescent
E.H.T. power supply grid

Figure 5.2 Deflection tube
2. Turn on switch S for the 6 V power supply and switch S
1 2
SCAN ME
for the E.H.T. power supply. Record your observations. SCAN ME
Demonstration
3. Turn on switch S at the E.H.T. power supply that is
3 video of a
connected to the deflection plates. Observe the cathode deflection tube
rays deflection on the fluorescent grid.
https://bit.ly/2Z92QZ9
4. Reverse the connection at the E.H.T. power supply that is,
connected to the deflection plates and repeat step 3.
5. Record all your observations.
Discussion:
Safety Precaution
State your observations on the fluorescent grid when: Safety Precaution
(a) switches S and S are turned on • Do not touch any metal part of the
1 2
(b) switches S , S and S are turned on deflection tube while using the
1 2 3 E.H.T. power supply.
(c) switches S , S and S are turned on and the potential
1 2 3 • Ensure that the E.H.T. power
difference at the deflection plates is reversed
supply is switched off when no
observations are made.

176 LS 5.1.2