A Quiz On Basic Power Electronics

1. A chopper can be used to step up a dc voltage.

True.

False.

A chopper is an electronic circuit that can convert a DC voltage to a higher or lower level through the use of switching components. By controlling the switching frequency and duty cycle, a chopper can step up the voltage level of a DC source. Therefore, it is true that a chopper can be used to step up a DC voltage.

Explanation

A chopper is an electronic circuit that can convert a DC voltage to a higher or lower level through the use of switching components. By controlling the switching frequency and duty cycle, a chopper can step up the voltage level of a DC source. Therefore, it is true that a chopper can be used to step up a DC voltage.

2. A dc chopper converts directly from dc to dc.

True.

False.

A DC chopper is an electronic circuit that converts a fixed DC voltage to a variable DC voltage. It does this by chopping the fixed DC voltage into a series of pulses and then filtering and averaging the output voltage. Therefore, it directly converts from DC to DC, making the statement true.

Explanation

A DC chopper is an electronic circuit that converts a fixed DC voltage to a variable DC voltage. It does this by chopping the fixed DC voltage into a series of pulses and then filtering and averaging the output voltage. Therefore, it directly converts from DC to DC, making the statement true.

3. A silicon controlled rectifier (SCR) is a

Unijunction device.

Device with 3 junctions.

Device with 4 junctions.

None of the above.

An SCR, or silicon controlled rectifier, is a device with 3 junctions. This means that it has 3 layers of semiconductor material, each forming a junction with the adjacent layer. The three junctions in an SCR are the anode-cathode junction, the anode-gate junction, and the cathode-gate junction. These junctions allow the SCR to control the flow of current in a circuit by acting as a switch that can be turned on and off.

Explanation

An SCR, or silicon controlled rectifier, is a device with 3 junctions. This means that it has 3 layers of semiconductor material, each forming a junction with the adjacent layer. The three junctions in an SCR are the anode-cathode junction, the anode-gate junction, and the cathode-gate junction. These junctions allow the SCR to control the flow of current in a circuit by acting as a switch that can be turned on and off.

4. Which of the following finds application in speed control of a dc motor?

FET

NPN transistor.

SCR.

None of the above.

The correct answer is SCR. SCR stands for Silicon Controlled Rectifier, which is a type of semiconductor device that can be used for speed control of a DC motor. SCR allows for precise control of the motor's speed by regulating the amount of power delivered to the motor. It is commonly used in industrial applications where precise speed control is required. FET and NPN transistor are not typically used for speed control of DC motors.

Explanation

The correct answer is SCR. SCR stands for Silicon Controlled Rectifier, which is a type of semiconductor device that can be used for speed control of a DC motor. SCR allows for precise control of the motor's speed by regulating the amount of power delivered to the motor. It is commonly used in industrial applications where precise speed control is required. FET and NPN transistor are not typically used for speed control of DC motors.

5. A triac is a

2 terminal switch.

2 terminal bilateral switch.

3 terminal unilateral switch.

3 terminal bidirectional switch.

A triac is a three-terminal bidirectional switch because it can conduct current in both directions when triggered by a small gate current. It is commonly used in AC power control applications, where it can control the flow of current in both positive and negative half-cycles of the AC waveform. The three terminals of a triac are the main terminal 1 (MT1), main terminal 2 (MT2), and the gate terminal. The bidirectional switching capability of a triac makes it suitable for controlling power to devices that require AC voltage, such as lamps, motors, and heaters.

Explanation

A triac is a three-terminal bidirectional switch because it can conduct current in both directions when triggered by a small gate current. It is commonly used in AC power control applications, where it can control the flow of current in both positive and negative half-cycles of the AC waveform. The three terminals of a triac are the main terminal 1 (MT1), main terminal 2 (MT2), and the gate terminal. The bidirectional switching capability of a triac makes it suitable for controlling power to devices that require AC voltage, such as lamps, motors, and heaters.