[Legacy] Introductory Electronics

Explain how a continuous flow of electrons from the filament is produced in this apparatus.

When an electron is in an electric field there is a force on the electron.

The direction of this force is in the opposite direction to the electric field.

Describe how the metal plates in Fig. 8.1 can be used to show this.

Describe how the electrons are produced by the filament and how they are then accelerated.

Explain why the glass tube is evacuated.

The instruction booklet for a c.r.o. states that strong magnets must not be placed close to the c.r.o.

Explain why a strong magnet close to the c.r.o. deflects the electron beam.

Explain what is meant by thermionic emission.

Electrons hit the screen at high speed.

Explain how the electrons are made to travel at high speed.

The spot on the screen is made to move up and down and also across the screen.

The parts of the c.r.o. that make this happen are not shown in Fig. 8.1.

On Fig. 8.1, draw and label the parts that are needed.

Explain why reversing battery A has no effect on the electron beam.

The connections to battery B are reversed. State and explain the effect on the electron beam.

State the name of the charged particles that are emitted.

Explain what causes the particles to be emitted.

State why there must be a vacuum in the c.r.o. tube.

On Fig. 10.1, write the names of parts B, D, E and F in the spaces provided.

part B,

part D.

State the useful energy change that occurs as electrons hit the screen of the c.r.o.

Describe what happens inside the c.r.o. to turn the spot into a horizontal line.

On Fig. 11.2 write, in the five empty boxes, the names of the parts of the c.r.o. indicated.

Explain how the electron beam is produced.

Explain why the tube of the c.r.o. must be evacuated.

______

Describe what is meant by thermionic emission.

State why air must be removed from the tube of the c.r.o.

A voltage is connected across the Y-plates in the c.r.o.

State and explain the effect on the trace on the screen.

State the colours of the bands on a $1500\ \Omega$ resistor.

band 1 ______
band 2 ______
band 3 ______

Determine the maximum value of resistance that can be shown with this three-band colour code.

resistance = ______

The $1500\ \Omega$ resistor on the electronic circuit board has a correct power rating of $0.25\ \text{W}$.

State a disadvantage of using a different $1500\ \Omega$ resistor with a power rating that is

(1) much less than $0.25\ \text{W}$,

(2) much greater than $0.25\ \text{W}$.