The video explains the piezoelectric effect, where mechanical energy is converted into electrical energy. It demonstrates how a piezoelectric device can light up LEDs by compressing and decompressing, causing current to flow in different directions. The video also covers how to capture this energy using a circuit with diodes, capacitors, and resistors, and discusses the efficiency of different circuit designs. Finally, it explains the working principle of piezoelectric devices, focusing on the role of quartz crystals and charge imbalances.

What happens when a piezoelectric device is compressed?

• It changes color.

• It produces an electric current.

• It generates a magnetic field.

• It emits light.

How are the LEDs connected in the demonstration of the piezoelectric effect?

• In a loop

• Anti-parallel

• In parallel

• In series

What is the role of a diode in capturing energy from a piezoelectric device?

• To decrease resistance

• To increase voltage

• To allow current to flow in one direction

• To store energy

Why is a capacitor used in the circuit with a piezoelectric device?

• To reduce voltage

• To convert AC to DC

• To store electrical energy

• To amplify sound

What is a disadvantage of using a silicon diode in the circuit?

• It is not durable.

• It is too expensive.

• It has a high voltage drop.

• It cannot conduct electricity.

How does a bridge rectifier improve the efficiency of the circuit?

• By allowing current to flow in both directions

• By increasing the voltage

• By reducing the current

• By storing more energy

What material is commonly used in piezoelectric devices?

• Copper

• Plastic

• Quartz

• Iron

What happens to the dipole moments in a quartz crystal when compressed?

• They become neutral.

• They cancel out completely.

• They align perfectly.

• They no longer cancel out.

What is the result of a charge imbalance in a piezoelectric crystal?

• It causes current to flow.

• It becomes electrically neutral.

• It generates heat.

• It creates a magnetic field.

What is the primary function of a piezoelectric device?

• To convert electrical energy into mechanical energy

• To convert mechanical energy into electrical energy

• To store electrical energy

• To emit light