Which component stores the electrical charge of a circuit and can be used for timing with a resistor?

Which component stores the electrical charge of a circuit and can be used for timing with a resistor?

• A. Capacitor
• B. Battery
• C. Conductor
• D. Buzzer

Answer: (A)

Storing charge and timing with a resistor relies on a capacitor. A capacitor holds electrical charge on its plates, with Q = C V, so the voltage across it reflects how much charge is stored. In a timing circuit, a resistor feeds the capacitor, and the pace of charging (or discharging) is set by the time constant RC. The capacitor voltage rises toward the supply as V(t) = V_source (1 − e^(−t/RC)) during charging, so larger RC values mean a longer delay. When the supply is removed, the capacitor discharges through the resistor with V(t) = V_initial e^(−t/RC), again giving a predictable timing interval. The other components don’t provide this charge-storage and controlled timing behavior: a battery is a energy source, not a charge reservoir for timing; a conductor doesn’t store net charge; a buzzer is a device that makes sound, not a timing element.

Storing charge and timing with a resistor relies on a capacitor. A capacitor holds electrical charge on its plates, with Q = C V, so the voltage across it reflects how much charge is stored. In a timing circuit, a resistor feeds the capacitor, and the pace of charging (or discharging) is set by the time constant RC. The capacitor voltage rises toward the supply as V(t) = V_source (1 − e^(−t/RC)) during charging, so larger RC values mean a longer delay. When the supply is removed, the capacitor discharges through the resistor with V(t) = V_initial e^(−t/RC), again giving a predictable timing interval. The other components don’t provide this charge-storage and controlled timing behavior: a battery is a energy source, not a charge reservoir for timing; a conductor doesn’t store net charge; a buzzer is a device that makes sound, not a timing element.