The figure shows the variation of \(R\), \(X_L\), and \(X_C\) with frequency \(f\) in a series of \(L\), \(C\), and \(R\) circuits. For which frequency point is the circuit inductive?
1. | \(A\) | 2. | \(B\) |
3. | \(C\) | 4. | All points |
Consider now the following statements
I. | Readings in \(A\) and \(V_2\) are always in phase |
II. | Reading in \(V_1\) is ahead in phase with reading in \(V_2\) |
III. | Readings in \(A\) and \(V_1\) are always in phase |
1. | I only | 2. | II only |
3. | I and II only | 4. | II and III only |
A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v is:
1. Zero
2. and P is at the higher potential
3. and R is at the higher potential
4. 2BvR and R is at the higher potential
A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate . Loop 1 of radius R > r encloses the region r and loop 2 of radius R is outside the region of the magnetic field as shown in the figure. Then, the emf generated is:
1. Zero in loop 1 and zero loop 2
2. in loop 1 and zero in loop 2
3. in loop 1 and zero in loop 2
4. Zero in loop 1 and not defined in loop 2
The key K is inserted at time t= 0. The initial (t=0) and final currents through battery are :
1.
2.
3.
4.
An electron moves on a straight-line path XY as shown. The abcd is a coil adjacent to the path of electrons. What will be the direction of current if any, induced in the coil?
,
1. abcd
2. adcb
3. The current will reverse its direction as the electron goes past the coil
4. No current included
The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux ϕ linked with the primary coil is given by ϕ=+4t, where ϕ is in weber, t is time in second and ϕ0is a constant, the output voltage across the secondary coil is:
1. 90 V
2. 120 V
3. 220 V
4. 30 V
While keeping area of cross-section of a solenoid same, the number of turns and length of solenoid one both doubled. The self inductance of the coil will be
1. halved
2. doubled
3. times the original value
4. unaffected
For a transparent medium, relative permeability and permittivity,\(\mu_r~\text{and}~\varepsilon_r\) are \(1.0\) and \(1.44\) respectively. The velocity of light in this medium would be:
1. \(2.5\times10^{8}~\text{m/s}\)
2. \(3\times10^{8}~\text{m/s}\)
3. \(2.08\times10^{8}~\text{m/s}\)
4. \(4.32\times10^{8}~\text{m/s}\)
The intensity of visible radiation at a distance of 1 m from a bulb of 100 W which converts only 5% its power into light is :
(1) 0.4 (2) 0.5
(3) 0.1 (4) 0.01
The charge of a parallel plate capacitor is varying as . Then find the magnitude of displacement current through the capacitor. (Plate Area = A, separation of plates = d)
(1) (2)
(3) (4)
The energy density of the electromagnetic wave in vacuum is given by the relation
(1) (2)
(3) (4)
An inductor 20 mH, a capacitor 100 μF, and a resistor 50 are connected in series across a source of emf, V= 10sin314t. The power loss in the circuit is:
1. 0.79 W
2. 0.43 W
3. 2.74 W
4. 1.13 W
1. | When the capacitor is air-filled. |
2. | When the capacitor is mica filled. |
If the current through the resistor is \(I\) and the voltage across the capacitor is \(V\), then:
1. \(V_a < V_b\)
2. \(V_a > V_b\)
3. \(i_a > i_b\)
4. \(V_a = V_b\)
In a certain circuit current changes with time according to . Root mean square value of current between t=2 to t=4s will be:-
1.
2.
3.
4.