Electromagnetic...

A wheel with 20 metallic spokes each of length 0.8 m long is rotated with a speed of 120 revolution per minute in a plane normal to the horizontal component of earth magnetic field H at a place. If H=$$0.4\times 10^{-4}$$ T at the place, then induced emf between the axle and the rim of the wheel is

When a coil rotated in magnetic field induced current in it :

As shown in figure, two vertical conducting rails separated by distance $$1.0\ m$$ are placed parallel to z-axis. At $$z = 0$$, a capacitor of $$0.15\ F$$ is connected between the rails and a metal rod of mass $$100\ gm$$ placed across the rails slides down along the rails. If a constant magnetic fields of $$2.0\ T$$ exists perpendicular to the plane of the rails, what is the acceleration of the rod?
(Take $$g = 9.8\ m/s^{2})$$.

An air-cored solenoid with length $$20 cm$$, area of cross-section is $$20 cm^2$$ and the number of turns $$400$$ carries a current  $$2 A$$. The current is suddenly switched off within $$10^{-3}$$ sec. The average back emf induced across the end of the open switch in the circuit is ( ignore variation in the magnetic field near the end of the solenoid) 

A current $$i$$ is flowing in a straight conductor of length $$L$$. The magnetic induction at the point on its perpendicular bisector at a distance $$L/4$$ from its centre will be

Figure shows a circular area of radius $$R$$ where a uniform magnetic field $$\vec { B }$$ is going into the plane of paper and increasing in magnitude at a constant rate. In rate case, which of the following graphs, drawn schematically, correctly shown the variation of the induced electric field $$E(r)$$?

A bulb of rated values 60 V and 10 W is connected in series with a source of 100 V and 50 Hz. The coefficient of self induction of a coil to be connected in series for its operation will be:

One of the two small circular coils, (none of them having any self-inductance) is suspended with a $$V-$$shaped copper wire, with plane horizontal. The other coil is placed just below the first one with plane horizontal. Both the coil are connected in series with a $$dc$$ apply. The coils are found to attract each other with a force. Which one of the following statement is incorrect?

Two coils, $$X$$ and $$Y$$, are kept inclose vicinity of each other. When a varying current, $$l(t)$$, flows through coil $$X$$, the induced emf $$(V(t))$$ in coil $$YY$$, varies in the manner shown here. The variation of $$l(t)$$, with time, can then represented by the graph labelled as graph.

A coil of inductance $$8.4\ mH$$ and resistance $$ 6 \Omega$$ is connected to a $$12\ V$$ battery. The current in the coil is $$1.0\ A$$ at the time, approximately