Advertisements
Advertisements
Question
An electric lamp is connected in series with a capacitor and an AC source is glowing with a certain brightness. How does the brightness of the lamp change on increasing the capacitance?
Solution
Capacitive reactance:
`"X"_"C" = 1/(2pi"fC")`
The capacitive reactance is inversely proportional to the capacitance. The capacitive reactance decreases as the capacitance increases. The current flow increases as capacitive reactance decreases. The brightness is proportional to the magnitude of the current, therefore the brightness of the bulb increases as the current increases. Therefore it can be concluded that the brightness of the bulb increases as the capacitance increases.
APPEARS IN
RELATED QUESTIONS
Choose the correct option.
If the rms current in a 50 Hz AC circuit is 5A, the value of the current 1/300 seconds after its value becomes zero is ______.
Choose the correct option.
In a circuit L, C and R are connected in series with an alternating voltage of frequency f. the current leads the voltage by 45°. The value of C is ______.
In an AC circuit, e and i are given by e = 150 sin(150t)V and i = 150 sin `(150t + π/3)` A. The power dissipated in the circuit is ______.
An electric current in an LC – circuit at resonance is called - ______
If AC voltage is applied to a pure capacitor, then the voltage across the capacitor ______
An electric bulb operates 10 V d.c. If this bulb is connected to an a.c. source and gives normal brightness, then the peak value of the source is ______
A coil of resistance 300Ω and inductance 1.0 H is connected across an alternating voltage of frequency `300/(2pi)` Hz, therefore phase difference between the voltage and current in the circuit is ______
Define capacitive reactance.
If the peak value of an alternating emf is 15V, what is its mean value over half cycle?
Explain term impedance and state the formula for it in the case of an LCR series circuit.
A series LCR circuit has resistance 10Ω and reactance is `7sqrt2` Ω. What is the impedance of the circuit?
Find the current in a circuit consisting of a coil and a capacitor in series with an A.C source of 110V (r.m.s.), 60Hz. The inductance of a coil is 0.80 H and its resistance is 50Ω. The capacitance of a capacitor is 8µF.
A 0.5µF capacitor is discharged through a 10 millihenry inductor. Find the frequency of discharge.
What is the capacitive reactance of a capacitor of 5µF at a frequency of (1) 50 Hz and (2) 20KHZ?
What is the inductive reactance of a coil of inductance 10mH at a frequency
- 50 Hz
- 1000 Hz
- 20 kHz?
Explain the term inductive reactance. State its unit and dimensions.
Obtain the expression for the applied emf and the effective resistance of the circuit when alternating emf is applied to an LR circuit.
Obtain the expression for the applied emf and the effective resistance of the circuit when alternating emf is applied to a CR circuit.
The standard voltage of A.C. mains in India is ______
A telegraph line of length 100 km has a capacity of 0.01 µF/ km and it carries an alternating current at 0.5 kilo cycle per second. If minimum impedance is required, then the value of the inductance that needs to be introduced in series is ______ mH. (if π = `sqrt10`)
