Advertisements
Advertisements
प्रश्न
An AC source is rated 220 V, 50 Hz. The average voltage is calculated in a time interval of 0.01 s. It
पर्याय
must be zero
may be zero
is never zero
`is (220//sqrt2 )V`
Advertisements
उत्तर
may be zero
Let the AC voltage be given by,
`V = V_0sin omegat`
Here, ω = `2pi` f = 314 rad/s
The average voltage over the given time,
Here, ω = `2pi` f = 314 rad/s
The average voltage over the given time,
Vavg = \[\frac{\int_0^{0.01}Vdt}{\int_0^{0.01}dt}\]=` -V_0 [(cos omega)/omega]_0^0.01`
= `V_0/(wxx0.01) (1 - cospi)`
= `(2V_0)/pi=140.127V`
Also, when V = V_0 cos `omegat`
Vavg =\[\frac{\int_0^{0.01}Vdt}{\int_0^{0.01}dt}\]=` -V_0 [(cos omega)/omega]_0^0.01`
=` V_0 /(omegaxx0.01) (sin omega(0.01)-0)`
=`V_0/(314xx0.01)(sin omega (0.01)-0)`
= `V_0/3.14 (sinpi)`
=0
From the above results, we can say that the average voltage can be zero. But it is not necessary that it should be zero or never zero.
APPEARS IN
संबंधित प्रश्न
When an AC source is connected to a capacitor, there is a steady-state current in the circuit. Does it mean that the charges jump from one plate to the other to complete the circuit?
A current i1 = i0 sin ωt passes through a resistor of resistance R. How much thermal energy is produced in one time period? A current i2 = −i0 sin ωt passes through the resistor. How much thermal energy is produced in one time period? If i1 and i2 both pass through the resistor simultaneously, how much thermal energy is produced? Is the principle of superposition obeyed in this case?
A transformer is designed to convert an AC voltage of 220 V to an AC voltage of 12 V. If the input terminals are connected to a DC voltage of 220 V, the transformer usually burns. Explain.
An AC source producing emf ε = ε0 [cos (100 π s−1)t + cos (500 π s−1)t] is connected in series with a capacitor and a resistor. The steady-state current in the circuit is found to be i = i1 cos [(100 π s−1)t + φ1) + i2 cos [(500π s−1)t + ϕ2]. So,
A bulb rated 60 W at 220 V is connected across a household supply of alternating voltage of 220 V. Calculate the maximum instantaneous current through the filament.
The dielectric strength of air is 3.0 × 106 V/m. A parallel-plate air-capacitor has area 20 cm2 and plate separation 0.10 mm. Find the maximum rms voltage of an AC source that can be safely connected to this capacitor.
A transformer has 50 turns in the primary and 100 in the secondary. If the primary is connected to a 220 V DC supply, what will be the voltage across the secondary?
When an ac voltage of 220 V is applied to the capacitor C, then ______.
A capacitor has capacitance C and reactance X, if capacitance and frequency become double, then reactance will be ______.
In the LCR circuit shown in figure, the ac driving voltage is v = vm sin ωt.
- Write down the equation of motion for q (t).
- At t = t0, the voltage source stops and R is short circuited. Now write down how much energy is stored in each of L and C.
- Describe subsequent motion of charges.
Define Capacitive reactance.
An a.c. source generating a voltage ε = ε0 sin ωt is connected to a capacitor of capacitance C. Find the expression for the current I flowing through it. Plot a graph of ε and I versus ωt to show that the current is ahead of the voltage by π/2.
A resistor of 50 Ω, a capacitor of `(25/pi)` µF and an inductor of `(4/pi)` H are connected in series across an ac source whose voltage (in volts) is given by V = 70 sin (100 πt). Calculate:
- the net reactance of the circuit
- the impedance of the circuit
- the effective value of current in the circuit.
A 40 µF capacitor is connected to a 200 V. 50 Hz ac supply. The rms value of the current on the circuit is, nearly ______.
In an ac circuit an alternating voltage e = 200\[\sqrt 2\] sin100t volts is connected to capacitor of capacity 1 µF. The r.m.s. value of the current in the circuit is ______.
When an AC voltage of 220 V is applied to the capacitor C ______.
The resistance of a coil for d.c. is 5 Ω. In a.c., the resistance will ______.
