Elektronika Dasar 006 Capasitor 02 Universitas Jember

Summary

This video explains the behavior of capacitors in electrical circuits, focusing on their charging and discharging processes. It demonstrates how a capacitor charges through a resistor, with current flowing rapidly at first and then slowing down. The capacitor reaches a point where it stops charging, at which time the current ceases. It also showcases how capacitors can be used to introduce time delays, such as lighting up an LED after a delay once the capacitor is charged. The practical demonstration further highlights how capacitors store and discharge energy, emphasizing their role in time delay circuits.

Takeaways

• 😀 Capacitors charge and discharge in a circuit, affecting the flow of current.
• 😀 The charging process is initially fast, with current reaching a maximum before gradually decreasing.
• 😀 The time constant (RC) determines how fast a capacitor charges or discharges.
• 😀 After five time constants (5RC), a capacitor is almost fully charged or discharged.
• 😀 The time constant is calculated by multiplying resistance (R) and capacitance (C).
• 😀 For example, with a 1kΩ resistor and a 100µF capacitor, the time constant is 100 milliseconds.
• 😀 Capacitors can delay electrical events, such as the turning on of a light bulb, by controlling the flow of current.
• 😀 When charging, the voltage across the capacitor rises quickly initially, then gradually approaches the supply voltage.
• 😀 Once fully charged, the current stops flowing, and the capacitor's voltage reaches the input voltage.
• 😀 When discharging, the capacitor voltage drops rapidly at first and slowly approaches zero.
• 😀 Capacitors can be used in circuits for time delay applications, as shown in the demonstration with an LED light.

Q & A

What is the purpose of the capacitor in the circuit described in the script?

The capacitor is used to store electrical charge and create a delay or time-lag in the circuit's behavior, such as turning on the light after a delay when the switch is pressed.

How does the current behave when the switch is first closed?

When the switch is first closed, the current flows quickly through the circuit, reaching its maximum value initially.

What happens to the current over time after the switch is closed?

The current gradually decreases as the capacitor charges. The rate of decrease is governed by the time constant, which is the product of the resistance (R) and capacitance (C), and the current slows down over time.

What is the significance of the time constant (RC) in the circuit?

The time constant (RC) represents the time it takes for the capacitor to charge or discharge significantly. At 5RC, the capacitor is almost fully charged or discharged.

What is the voltage across the capacitor at the start of the charging process?

At the start, the voltage across the capacitor is 0V. As the capacitor charges, the voltage increases rapidly, approaching the supply voltage.

What happens when the capacitor is fully charged in the circuit?

Once the capacitor is fully charged, the current stops flowing, and the voltage across the capacitor becomes nearly equal to the supply voltage.

What happens to the voltage when the capacitor discharges through a resistor?

When the capacitor discharges, the voltage drops from the initial value (e.g., 9V) towards 0V over time, following an exponential decay pattern.

Why does the light remain off until the capacitor is fully charged in the example with the lamp?

The light remains off because the voltage across the capacitor is initially too low to power the light. The light only turns on once the capacitor is fully charged and can deliver sufficient voltage.

What is the role of the resistor in the circuit with the capacitor and LED light?

The resistor limits the current flowing into the capacitor and controls the charging and discharging rate of the capacitor, thereby regulating the time delay before the light turns on or off.

What happens when the capacitor's charge is discharged quickly by short-circuiting it?

When the capacitor is short-circuited, its stored charge is rapidly dissipated, and the voltage across it drops to zero quickly, effectively resetting the capacitor for the next cycle.