Capacitance of a parallel plate capacitor becomes times its original value if a dielectric slab of thickness is inserted between the plates, where d is the separation between the plates. The dielectric constant of the slab is
4
2
3
1
The electric potential V at any point x, y, z in space is given by V = 4 x2 . The electric field at the point (2, 0, 1) in Vm-1 is
10
20
− 16
30
The electric field in a region is given by E = V/m. The net flux passing through a square area of side 4 m parallel to y-z plane is
32 V-m
16 V-m
12 V-m
64 V-m
D.
64 V-m
A square area of side 4 m parallel to y-z plane in vector form can be written as
The current in a wire varies with time as I = 5t2 + 2t, where I is in ampere and t is in second. The quantity of charge which has to be passed through a cross-section of wire during the times t = 4 s to t = 6 s is
220 C
340 C
273.34 C
280 C
Three resistances of 2 Ω, 3 Ω and 6 Ω are connected in parallel and the combination is connected in series with 2 V battery having internal resistance of 1 Ω . The current in the battery is
1 A
3 A
2 A
4 A
An electric cable of copper has just one wire of radius 9 mm with resistance 5 Ω . This single copper wire of cable is replaced by 4 different well insulated copper wires each of radius 3 mm. The total resistance of the cable now will be
22.5 Ω
45 Ω
9 Ω
11.25 Ω
A rise of temperature 5°C is observed in a conductor by passing a current. If the current is doubled the rise in temperature will be
10°C
20°C
5°C
25°C
The current density varies with radial distance r as J =ar2 (where, a is a constant) in a cylindrical wire of radius R. The current passing through the wire between radial distance and is
An electron having mass 9.1 x 10-31 kg moves in a circular path of radius 0.4 m with velocity 105 m/s in a magnetic field. The strength of magnetic field is
1.56 × 10-5 T
1.62 × 10-4 T
1.42 x 10-6 T
1.88 × 10-5 T
A current of 0.4 A is passed through the coil of galvanometer having 500 turns and each turn has an average area of 3 x 10-4 m2 . If a torque of 2 Nm is required for this coil carrying some current to set it parallel to a magnetic field then the strength of magnetic field will be
31 T
33.34 T
32 T
40 T