A potentiometer has uniform potential gradient across it. Two cells connected in series (i) to support each other and (ii) to oppose each other are balanced over 6m and 2m respectively on the potentiometer wire. The e.m.f.’s of the cells are in the ratio of
|
(a) 1 : 2 |
(b) 1 : 1 |
(c) 3 : 1 |
(d) 2 : 1 |
(d) 2 : 1
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Two very thin metallic wires placed along X and Y-axis carry equal currents as shown here. AB and CD are lines at 45° with the axes with origin of axes at O. The magnetic field will be zero on the line
|
(a) AB |
(b) CD |
|
(c) Segment OB only of line AB |
(d) Segment OC only of line CD |
A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V. If the shell is now given a charge of –3Q, the new potential difference between the same two surfaces is
|
(a) V |
(b) 2V |
(c) 4V |
(d) – 2V |
The magnetic induction at a point P which is distant 4 cm from a long current carrying wire is 
. The field of induction at a distance 12 cm from the same current would be
|
(a) 3.33 |
(b) 1.11 |
(c) 3 |
(d) 9 |
When a beam of accelerated electrons hits a target, a continuous X-ray spectrum is emitted from the target. Which of the following wavelength is absent in the X-ray spectrum, if the X-ray tube is operating at 40,000 volts
| (a) 0.25 Å | (b) 0.5 Å | (c) 1.5 Å | (d) 1.0 Å |
