Same current i = 2A is flowing in a wire frame as shown in figure. The frame is a combination of two equilateral triangles ACD and CDE of side 1m. It is placed in uniform magnetic field B = 4T acting perpendicular to the plane of frame. The magnitude of magnetic force acting on the frame is
|
(a) 24 N |
(b) Zero |
(c) 16 N |
(d) 8 N |
(a) 24 N
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A motor having an armature of resistance 2Ω is designed to operate at 220 V mains. At full speed, it develops a back e.m.f. of 210V. When the motor is running at full speed, the current in the armature is
|
(a) 5A |
(b) 105A |
(c) 110A |
(d) 215A |
A horizontal rod of mass 10 gm and length 10 cm is placed on a smooth plane inclined at an angle of 60° with the horizontal, with the length of the rod parallel to the edge of the inclined plane. A uniform magnetic field of induction B is applied vertically downwards. If the current through the rod is 1.73 ampere, then the value of B for which the rod remains stationary on the inclined plane is
|
(a) 1.73 Tesla |
(b) |
(c) 1 Tesla |
(d) None of the above |
When a ray of light emerges from a block of glass, the critical angle is
|
(a) Equal to the angle of reflection |
|
(b) The angle between the refracted ray and the normal |
|
(c) The angle of incidence for which the refracted ray travels along the glass-air boundary |
|
(d) The angle of incidence |
An ionization chamber with parallel conducting plates as anode and cathode has 5 
electrons and the same number of singly-charged positive ions per 
. The electrons are moving at 0.4 m/s. The current density from anode to cathode is 
. The velocity of positive ions moving towards cathode is
|
(a) 0.4 m/s |
(b) 16 m/s |
(c) Zero |
(d) 0.1 m/s |
A convex lens forms a real image of an object for its two different positions on a screen. If height of the image in both the cases be 8 cm and 2 cm, then height of the object is
|
(a) 16 cm |
(b) 8 cm |
(c) 4 cm |
(d) 2 cm |
A and B are two concentric circular conductors of centre O and carrying currents 
and 
as shown in the adjacent figure. If ratio of their radii is 1 : 2 and ratio of the flux densities at O due to A and B is 1 : 3, then the value of 
is
|
(a) |
(b) |
(c) |
(d) |
For germanium crystal, the forbidden energy gap in joules is
|
(a) 1.12 |
(b) 1.76 |
(c) 1.6 |
(d) Zero |
A charge produces an electric field of 1 N/C at a point distant 0.1 m from it. The magnitude of charge is
|
(a) 1.11 |
(b) 9.11 |
(c) 7.11 |
(d) None of these |
