CBSE
The sun delivers 104 W/m2 of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimension (10 x 10) m2 will be
104 W
105 W
106 W
107 W
Current in a circuit falls steadily from 2.0 A to 0.0 A in 10 ms. If an average emf of 200 V is induced, then the self-inductance of the circuit is
1 H
2 H
1/2 H
2 H
Three solenoid coils of same dimensions, same number of turns and same number of layers of windings are taken. Coil 1 with inductance L1 was wound using a wire of resistance 11 Ω /m, coil 2 with inductance L2 was wound using the similar wire but the direction of winding was reversed in each layer, coil 3 with inductance L3 was wound using a superconducting wire. The self inductance of the coils L1 , L2 and L3 are
L1 = L2 = L3
L1 = L2 , L3 = 0
L1 = L3 , L2 = 0
L1 > L2 > L3
When a given coil is connected to a 200V, 50 Hz AC source, 1 A current flows in the circuit. The inductive reactance of the coil used is
The self-inductance of the motor of an electric fan is 10H. In order to impart maximum power at 50 Hz, it should be
connected to a capacitance of
4µF
8µF
1µF
2µF
The magnetic flux in a closed circuit of resistance 10 Ω varies with time t (in second) as = (4t2 − 5t + 1)Wb. The magnitude of induced current at t = 0.20 s is
0.12 A
0.38 A
0.34 A
0.12 A
The magnetic flux through a circuit of resistance R changes by Δ in times Δt. Then, the-total amount of electric charge that passes in any point in the circuit during this time 'Δt' will be
The polarity of the capacitor in the situation described by Fig.
Plate A and plate B both positive
Plate A negative and plate B positive
Plate A positive and plate B negative
Plate A and plate B both negative
A small piece of metal wire is dragged across the gap between the poles of a magnet in 0.4 s. If change in magnetic flux in the wire is 8 x 10-4 Wb, then emf induced in the wire is
8 × 10-3 V
6 × 10-3 V
4 × 10-3 V
2 × 10-3 V
A current I= 5.0 A flows along a thin wire shaped as shown in given figure. The radius of the curved part of the wire is equal to R = 120 mm and the angle 2 = 90°. Find the magnetic induction of the field at point O.
4.2 × 10-4 T
8.8 × 10-5 T
2.8 × 10-4 T
4.2 × 10-3 T