QUIZ CHAPTER 5

What is meant by thermionic emission?

• A process involving the acceleration of electrons from the cathode to the anode.

• A process used to produce beams of high velocity electrons

• A process involving the emission of electrons from a hot metal surface.

• A process where light is produced when electrons strike the fluorescent screen.

Which of the following will NOT affect the rate of thermionic emission from a metal?

• Type of metal

• Surface area of metal

• Nature of metal surface

• Colour of metal surface

Which of the following diagrams shows the correct movement of a cathode ray between two charged metal plates?

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An electron from a cathode being accelerated towards an anode. The potential difference across the two metal plates is 750 V. Calculate the speed of the electron that strikes the anode plate.

(Mass of electron = 9.1 x 10^-31 kg ; charge of electron = 1.6 x 10^-19 C)

• 5.92 x 10⁵ ms^-1

• 1.15 x 10⁷ ms^-1

• 1.62 x 10⁷ ms^-1

• 2.64 x 10⁸ ms^-1

Which of the following statements is NOT true about cathode rays?

• Cathode rays are positively charged.

• Cathode rays are deflected by magnetic fields.

• Cathode rays consist of high-velocity electrons.

• Cathode rays possess momentum and kinetc energy.

Diagram above shows two sets of identical bulbs and diodes connected in two circuits, P and Q, separately.

What will happen to the bulb when both of the switches are turned off at the same time?

• P = on , Q = on

• P = off , Q = off

• P = on , Q = off

• P = off , Q = on

Which of the following is the symbol of pnp transistor?

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Diagram above shows a symbol for a type of transistor.

Which of the following are TRUE about the terminals P, Q and R?

• P = Collector, Q = Emitter, R = Base

• P = Emitter, Q = Base , R = Collector

• P = Base, Q = Collector , R = Emitter

• P = Collector, Q = Base, R = Emitter

Diagram above shows the value of the current flowing through an npn transistor.

What is the value of current I_c?

• 0.07 mA

• 1.51 mA

• 1.58 mA

• 1.65 mA

Diagram above shows an npn transistor connected to a direct power supply.

Which of the following is correct?

• I_E > I_C > I_B

• I_E > I_B > I_C

• I_C > I_E > I_B

• I_C > I_B > I_E