Science interview questions – page 2

An oscillator is nothing but an amplifier with

1. Negative feedback
2. No feedback
3. Large gain
4. Positive feedback

The unidirectional property of a pn-junction is useful for its use as a

1. Transformer
2. Amplifier
3. Oscillator
4. Rectifier

n-type of semiconductor is

1. Neutral
2. Negatively charged
3. Positively charged
4. None of these

The waves relevant to telecommunications are

1. Ultraviolet
2. Microwave
3. Visible light
4. Infrared

The electrical circuits used to get smooth dc output from a rectified circuit is called

1. Amplifier
2. Full wave rectifier
3. Filter
4. Oscillator

A diode as a rectifier converts

1. AC to DC
2. DC to AC
3. Varying DC into constant dc
4. High voltage into low voltage and vice-versa

The frequency band used for radar relay-systems and television is

1. EHF
2. UHF
3. VLF
4. VHF

Intelsat satellite is used for

1. Radar communication
2. Intercontinental communication
3. Radio communication
4. None of the above

Radio wave of constant amplitude can be generated with

1. Oscillator
2. FET
3. Filter
4. Rectifier

Which of the following is not a semiconductor?

1. Arsenic
2. Germanium
3. Silicon
4. All of these

Which of the following shows particle nature of high?

1. Refraction
2. Interference
3. Polarization
4. Photoelectric effect

A diode can be used for

1. Amplification
2. Rectification
3. Modulation
4. Detection

A transistor is made of

1. A metal piece sandwiched between two intrinsic semiconductors
2. Intrinsic semiconductors
3. Doped semiconductors
4. None of the above

In a transistor the emitter current is

1. Equal to the base current
2. Equal to the collector current
3. Slightly less than the collector current
4. Slightly more than the collector current

Modem is a device used for

1. Either of the above
2. Converting analog signals to digital signals
3. Modulating signals
4. None of the above

The technique of collecting information about an object from a distance without making physical contact with it is

1. Space shuttle
2. Remote accessing
3. Remote control
4. Remote sensing

Modern communication systems use

1. Digital circuits
2. Combination of analog and digital circuits
3. Analog circuits
4. None of the above

The absorption of radio waves by the atmosphere depends on

1. Their frequency
2. Their distance from the transmitter
3. Their polarization of the wave
4. The polarization of the atmosphere

A hole in p-type semiconductor is

1. An excess electron
2. A missing electron
3. A missing atom
4. A donor level

In black and white televisions, pictures on the screen are produced due to bombardment of

1. X-ray photons on a white screen
2. X-ray photons on a white fluorescent screen
3. Electrons on a fluorescent white screen
4. Electrons on a white screen

When the temperature of semiconductor is increased, its electrical conductivity

1. Remains the same
2. Increases
3. Decreases
4. None of these

The reciprocal of specific resistance is

1. Plate resistance
2. Resistance
3. Conductive resistance
4. Specific conductance

The expected energy of the electron at absolute zero is called

1. Fermi energy
2. Potential energy
3. Work function
4. Emission energy

Long distance short-wave radio broad casting uses

1. Ground wave
2. Ionospheric wave
3. Sky wave
4. Direct wave

The sky wave propagation is suitable for radio waves of frequency

1. Up to 2 MHz
2. From 2 MHz to 20 MHz
3. From 2 MHz to 30 MHz
4. From 2 MHz to 80 MHz

Antenna is

1. Resistive at resonant frequency
2. Resistive its resonant frequency
3. Capacitive
4. Inductive

Which of the following device is full duplex?

1. Radio
2. Mobile phone
3. Walky-talky
4. Loudspeaker

Intelsat satellite works as a

1. Absorber
2. Transmitter
3. Repeater
4. None of these

The audio signal

1. Can be sent directly over the air for distance
2. Possess very high frequency
3. Cannot be sent directly over the air for large distance
4. None of the above

Resistivity of semiconductor depends on

1. Atomic nature of semiconductor
2. Shape and atomic nature of semiconductor
3. Length of semiconductor
4. Shape of semiconductor