An ammeter whose resistance is 180 Ω gives full scale deflection when current is 2 mA. The shunt required to convert it into an ammeter reading 20 mA (in ohms) is
|
(a) 18 |
(b) 20 |
(c) 0.1 |
(d) 10 |
(b) 20
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Points A and B are situated perpendicular to the axis of a 2cm long bar magnet at large distances X and 3X from its centre on opposite sides. The ratio of the magnetic fields at A and B will be approximately equal to
|
(a) 1 : 9 |
(b) 2 : 9 |
(c) 27 : 1 |
(d) 9 : 1 |
Which of the following rays are not electromagnetic waves
|
(a) g-rays |
(b) b-rays |
(c) Heat rays |
(d) X-rays |
The rate of disintegration was observed to be 
disintegrations per sec when its half life period is 1445 years. The original number of particles are
(a) 8.9 
|
(b) 6.6
|
(c) 1.4 
|
(d) 1.2 
|
Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon
|
(a) Distance between slit and source |
(b) Wavelength of light used |
|
(c) Width of the slit |
(d) Frequency of light used |
A long straight wire carries a current of π amp. The magnetic field due to it will be 5 
at what distance from the wire [
permeability of air]
|
(a) |
(b) |
(c) |
(d) |
