Two similar coils are kept mutually perpendicular such that their centres coincide. At the centre, find the ratio of the magnetic field due to one coil and the resultant magnetic field by both coils, if the same current is flown
|
(a) 1: |
(b) 1 : 2 |
(c) 2 : 1 |
(d) |
(a) 1: 
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In order to quadruple the resistance of a uniform wire, a part of its length was uniformly stretched till the final length of the entire wire was 1.5 times the original length, the part of the wire was fraction equal to
|
(a) 1 / 8 |
(b) 1 / 6 |
(c) 1 / 10 |
(d) 1 / 4 |
The current in a simple series circuit is 5.0 amp. When an additional resistance of 2.0 ohms is inserted, the current drops to 4.0 amp. The original resistance of the circuit in ohms was
|
(a) 1.25 |
(b) 8 |
(c) 10 |
(d) 20 |
Figure given below shows a beam of light converging at point P. When a convex lens of focal length 16 cm is introduced in the path of the beam at a place O shown by dotted line such that OP becomes the axis of the lens, the beam converges at a distance x from the lens. The value x will be equal to
|
(a) 12 cm |
(b) 24 cm |
(c) 36 cm |
(d) 48 cm |
For photoelectric emission, tungsten requires light of 2300 Å. If light of 1800 Å wavelength is incident then emission
|
(a) Takes place |
(b) Don’t take place |
|
(c) May or may not take place |
(d) Depends on frequency |
A bar magnet of magnetic moment 
is placed in a magnetic field of induction 
. The torque exerted on it is
|
(a) |
(b) - |
(c) |
(d) |
A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length is
|
(a) R/ 2 |
(b) R |
(c) 2R |
(d) 1.5 R |
