Chapter 5 Form 5 - Electronic

The emission of electrons from the surface of a heated metal is called

• Vaporization

• Condensation

• Cathode emission

• Thermionic emission

An electron is accelerated between anode and cathode through a potential difference 8000 V. What is the maximum speed of the electron?

[ e =1.6 x 10 ^-19 C and m= 9 x 10 ^-31 ]

• 5.3 x 10⁷ m s^-1

• 4.3 x 10⁶ m s^-1

• 3.3 x 10⁴ m s^-1

• 2.3 x 10³ m s^-1

In a vacuum tube, the high voltage across anode and cathode used to

• control the fialament temperature

• control the number of electrons

• produce narrow beam electrons

• accelerate electrons with a high speed

Which diagram shows the correct movement of an electron beam in an electric field?

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What is the function of a diode?

• Stores electric charge

• Acts as a current amplifier

• Acts as an automatic switch

• Allows the current to pass in one direction only

Diagram shows a full wave rectifier circuit.

The output waves become smooth because

• the resistance of the resistor is always increasing and decreasing

• the charges in the capacitor is always increasing and decreasing

• the number of electrons in the CRO is always increasing and decreasing

• the current flows through the diode is always increasing and decreasing

Which of the following diagram shows the bulb does not light up.

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Which of the following circuits can function?

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Diagram shows the symbol of an npn transistor.

What is the value of I_e?

• 24 mA

• 115 mA

• 125 mA

• 600 mA

Diagram shows a transistor circuit.

The bulb will light up when the circuit in

• bright light

• dark room

• low temperature

• high temperature