This set of Basic Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Passive Circuit Components – Variable Resistors”.
1. A variable resistor is used to control the _____
a) Base, tone, volume
b) Base, volume, intensity
c) Base, volume, efficiency
d) Efficiency, tone, volume
View Answer
Explanation: A variable resistor is used to control the base, tone and volume. This is due to the resistors can be connected with the other components to make filters. In devices like rectifiers these variable resistors are used as filters.
2. When the potentiometer has only two terminals then it is called as ______
a) Preset
b) Digital potentiometer
c) Potential divider
d) Rheostat
View Answer
Explanation: The potential divider with three terminals is called potentiometer. If the potential divider has only two terminals then it is called rheostat. Rheostat is used to control the electric current by varying the resistance. Potential divider is to produce some voltage between two ends.
3. A potentiometer functions as ______
a) Potential reducer
b) Preset
c) Potential divider
d) Resistor
View Answer
Explanation: A potentiometer functions as the potential divider and the rheostat is similar to that of the potentiometer but it functions as the variable divider. Potentiometer or potential divider is also called as voltage divider. A series resistors or capacitors which can be tapped at any intermediate point to produce a specific fraction of the voltage applied between its ends.
4. Measurements of distance or angles can be measured by using _____
a) Ammeter
b) Potentiometer
c) Rheostat
d) Preset
View Answer
Explanation: Potentiometer is used to measure of distance or angles. It is also used for the amplifier gain control and tuning of circuits. Presets are used to adjust or control. Ammeter is used to measure the current flow across the circuit.
5. Rheostats are used as ______
a) Variable resistors
b) Potential dividers
c) Fixed resistors
d) Ammeters
View Answer
Explanation: Rheostats are used as variable resistors because they can vary the resistance of the resistors and it is connected to wipers and resistive elements. Wipers are the devices that are used to remove rain, snow and fog from the wind screen.
6. Rheostats are used as _____
a) Caliberate a circuit
b) Trim-pots
c) Power controlling devices
d) Amplifier gain control
View Answer
Explanation: Rheostats are used as the power controlling devices which were connected in series. As it is ineffective method now they are not used as power controlling devices. Now silicon control rectifiers, BJT are in usage.
7. The change of resistance is performed by the electronic signals then _______ are used.
a) Presets
b) Digital variable resistor
c) Rheostats
d) Potentiometers
View Answer
Explanation: The change of resistance is performed by the electronic signals then digital variable resistors are used and they are placed in the high-efficiency switching electronics for power control. Electronic signals are produced in the form of waves.
8. The change in resistance is controlled frequently by the ______
a) Digital protocols
b) Switch
c) Presets
d) Rheostat
View Answer
Explanation: The digital resistor is used to change the resistance in discrete steps and the change in resistance is controlled by the digital protocols or signals. The signals produced are in the form of waves and change in resistance depends upon the wave lengths.
9. The value of the resistance in presets are adjusted using ____
a) Screw-driver
b) Screw-gauge
c) Rheostat
d) Switch
View Answer
Explanation: The values of the resistance in presets are adjusted using the screw-driver that can loosen or tighten the screw that is attached to the preset. Generally, they are first adjusted and then they will be used.
10. In variable resistors, the electrical resistance are connected between the wiper terminal and _______
a) Input terminal
b) Output terminal
c) Track terminal
d) Ammeter terminal
View Answer
Explanation: In variable resistors, one of the terminals of the electrical resistances is connected to wiper terminal and the other is connected to the track terminal and they are together connected to output terminal.
11. The adoptable resistance can be achieved by connecting ______
a) Potentiometer
b) Rheostat
c) Digital resistor
d) Preset resistor
View Answer
Explanation: In the electronics circuit, the adoptable resistances are needed in some cases that is in very rare conditions. So, they are achieved by the preset resistors. Presets can be used as adaptable resistors.
12. The track in variable resistor is made up of ______
a) Ceramic
b) Mixture of ceramic and metal
c) Mixture of ceramic and copper
d) Mixture of metal and copper
View Answer
Explanation: The mixture of ceramic and metal is used ti make the track in variable resistor. Carbon can also be used to make the track. The mixture of metal and copper only forms an alloy that is not good for the variable resistors.
13. The voltage across the load terminals is the _______
a) Fraction of source voltage
b) Source voltage
c) Resistor voltage
d) Variable voltage
View Answer
Explanation: The voltage across the load terminals is the fraction of source voltage. The motion of the wiper throughout the track helps in increase and decrease the resistance.
14. Rheostats are used to control _______
a) Voltages
b) Resistance
c) Electric current
d) Potentials
View Answer
Explanation: Rheostats are mainly used to control the electric current not the voltages. The potentiometer is used to measure the potential drop across the circuit. Resistors show resistance for the current flow.
15. Variable resistors can be found in ________
a) Oscillators
b) Photo electric devices
c) Video control
d) Ovens
View Answer
Explanation: Variable resistors can be found in oscillators. They are also used in televisions, audio controls and motion controls. The transducers also contain the variable resistors. Variable resistors in oscillators control them by varying voltage.
Sanfoundry Global Education & Learning Series – Basic Electronics Engineering.
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