Electronic Circuits and Components

3. Indicate which of the following statements is true:

• • a) A thermistor is the same thing as a transistor.

• • b) A thermistor is a variable resistor that I can manually set to the desired value.

• • c) A transistor can amplify the electric current flowing through its base.

• • d) An LDR is a temperature-dependent variable resistor.

9. In the circuit of the figure, with a motor and a bulb, which statement is the correct one

• • There is a transistor that is allowing current by the motor but not by the bulb

• • There is an alternator that change current to bulb when motor works

• • There is a variable resistor allowing the current by the motor circuit and lighting up the bulb

• • There is a relay that is switching the circuit of the motor so bulb is lighting down

The attached symbol represents:

• a LDR

• a NTC

• a PTC

• a NPI

A relay is a electromagnetic device that:

• acts as a switch and is controlled by an electromagnet

• it is used to store and discharge electrical energy

• works like a power source increasing the role of the battery

• increases the current flow allowing changes in the current direction

A diode is an electronic component that:

• allows the current to flow in the anode-cathode direction, but no the reverse

• allows the current to flow in the cathode-anode direction, but no the reverse

• allows the current to flow in the anode-cathode direction, and the reverse if necessary

• acts as a variable resistor controlling the flow of the current

A two-terminal electronic component that conducts current in only one direction.

• Diode
• Light Emitting Diode
• Transistor
• Resistor

A resistor whose value can be varied between its minimum and maximum values.

• Fixed Resistor
• Variable Resistor
• Thermistor
• Transistor

In the circuit of the figure calculate how much time LED is lighting up if capacitor is full charged

• 3 seconds

• 1,5 minutes

• 2 minutes

• 1,5 seconds

The attached figure shows how resistance varies with temperature. Which of them is a PTC?

• A

• B

• C

What electronics symbol is shown?

• diode

• ground

• transistor

• transformer