Hi please check the attached file,
When switch A closes (B remain open), the light intensity is highest and voltage drop is 0, then the
voltage drop across the capacitor increases and the line intensity decreases. When the voltage drop
reach 25 V, the light intensity of both light bulb becomes 0. When B close and (A open), 20 ohm bulb
has no light, the light intensity of 10 ohm bulb is highest and the voltage cross capacitor is the largest at
the switch close. As the voltage drop across the capacitor decreases gradually, the light intensity also
When A closes B opens the two light bulbs and 10 ohm resistor are in series with the capacitor, the total
resistance of the circuit is 40 ohms. When A opens and B closes, only 10ohm resistor and 10ohm bulb
in series with the capacitor, the resistance of the circuit is 20 ohms. The time constant of RC circuit is RC.
This explains why it takes longer to charge the capacitor than discharge the capacitor.
As A closes, the time constant of the circuit in this case is
=RC = 40*0.2 = 8 s
The charging time is about 3=3*8 s = 24 s
This result is very close to to the simulation result of 241 s.
As B closes, the time constant of the circuit in this case is
=RC = 20*0.2 = 4 s
The charging time is 3=3*4 =12 s.
This result matches very well with the simulation result of 121 s.
For the circuit without the coil, when the switch is on, the light bulb goes bright almost immediately, and
it dim qui...
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