To measure capacitance using a reed switch

Set-up of apparatusSet-up of apparatus

Parallel-plate capacitor

Vibrating reed switch

Signal generator

Light beam galvanometer

Complete discharge of capacitanceComplete discharge of capacitance

C. R. O. connected across resistor in series with light beam galvanometer.

Decay curve drops to zero in half cycle.

Incomplete discharge of capacitanceIncomplete discharge of capacitance

C. R. O. connected across resistor in series with light beam galvanometer.

Decay curve cannot drop to zero in half cycle.