Advertisements
Advertisements
Question
The magnetic field energy in an inductor changes from maximum to minimum value in 5.0 ms when connected to an AC source. The frequency of the source is
Options
20 Hz
50 Hz
200 Hz
500 Hz
Advertisements
Solution
50 Hz
The magnetic field energy in an inductor is given by,
`E = 1/2 Li^2`
The magnetic energy will be maximum when the current will reach its peak value, i0, and it will be minimum when the current will become zero.
v
From the above graph of alternating current, we can see that current reduces from maximum to zero in T/4 time, where T is the time period.
So, in this case, T/4 = 5 ms
⇒ T = 20 ms
∴ Frequency , `V =1/T = 1/(20xx10^-3)=50Hz`
APPEARS IN
RELATED QUESTIONS
An inductance of 2.0 H, a capacitance of 18μF and a resistance of 10 kΩ is connected to an AC source of 20 V with adjustable frequency.
(a) What frequency should be chosen to maximize the current in the circuit?
(b) What is the value of this maximum current?
An inductor-coil, a capacitor and an AC source of rms voltage 24 V are connected in series. When the frequency of the source is varied, a maximum rms current of 6.0 A is observed. If this inductor coil is connected to a battery of emf 12 V and internal resistance 4.0 Ω, what will be the current?
Show that in an AC circuit containing a pure inductor, the voltage is ahead of current by π/2 in phase.
A 44 mH inductor is connected to 220 V, 50 Hz ac supply. Determine the rms value of the current in the circuit.
A coil of inductance 0.50 H and resistance 100 Ω is connected to a 240 V, 50 Hz ac supply.
(a) What is the maximum current in the coil?
(b) What is the time lag between the voltage maximum and the current maximum?
A 100 µF capacitor in series with a 40 Ω resistance is connected to a 110 V, 60 Hz supply.
(a) What is the maximum current in the circuit?
(b) What is the time lag between the current maximum and the voltage maximum?
Alternating current is so called because _______.
In a circuit containing resistance only, voltage and current are ______.
Average power supplied to an inductor over one complete cycle is ______.
If the frequency of an A.C. is made 4 times of its initial value, the inductive reactance will ______.
An inductive circuit contains resistance of 10 ohms and an inductance of 2 henry. If an A.C. voltage of 120 Volts and frequency 60 Hz is applied to this circuit, the current would be nearly ______.
Explain why the reactance offered by an inductor increases with increasing frequency of an alternating voltage.
An electrical device draws 2kW power from AC mains (voltage 223V (rms) = `sqrt(50,000)` V). The current differs (lags) in phase by `phi(tan phi = (-3)/4)` as compared to voltage. Find (i) R, (ii) XC – XL, and (iii) IM. Another device has twice the values for R, XC and XL. How are the answers affected?
An ac voltage V = V0 sin ωt is applied across a pure inductor of inductance L. Find an expression for the current i, flowing in the circuit and show mathematically that the current flowing through it lags behind the applied voltage by a phase angle of `π/2`. Also draw graphs of V and i versus ωt for the circuit.
An ideal inductor is connected across an AC source of voltage. The current in the circuit ______.
The magnetic energy stored in an inductor of inductance 4 µH carrying a current of 2 A is ______.
In an AC circuit with a bulb and inductor, what happens to the bulb’s brightness when an iron rod is inserted into the inductor?
The inductive reactance XL of a purely inductive circuit is given by ______.
