A 5℃ rise in temperature is observed in a conductor by passing a current. When the current is doubled the rise in temperature will be approximately
|
(a) 16 ℃ |
(b) 10 ℃
|
(c) 20 ℃ |
(d) 12 ℃ |
(c) 20 ℃
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The magnetic potential at a point on the axial line of a bar magnet of dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment 
at the same point
| (a) 4V | (b) 2V |
(c) 
|
(d) 
|
Through two parallel wires A and B, 10 and 2 ampere of currents are passed respectively in opposite direction. If the wire A is infinitely long and the length of the wire B is 2 m, the force on the conductor B, which is situated at 10 cm distance from A will be
|
(a) 8 |
(a) 8 |
(c) 4 |
(d) 4π |
The energy stored in the condenser is
|
(a) QV |
(b) |
(c) |
(d) |
The electron emitted in beta radiation originates from
|
(a) Inner orbits of atoms |
(b) Free electrons existing in nuclei |
|
(c) Decay of a neutron in a nucleus |
(d) Photon escaping from the nucleus |
The magnetic field at the centre of a circular coil of radius r carrying current I is 
. The field at the centre of another coil of radius 2 r carrying same current I is 
. The ratio 
is
|
(a) |
(b) 1 |
(c) 2 |
(d) 4 |
Two point charges of 20μC and 80 μC are 10 cm apart. Where will the electric field strength be zero on the line joining the charges from 20 μC charge
|
(a) 0.1 m |
(b) 0.04 m |
(c) 0.033 m |
(d) 0.33 m |
For a thermocouple the neutral temperature is 270℃ when its cold junction is at 20℃. What will be the neutral temperature and the temperature of inversion when the temperature of cold junction is increased to 40 ℃
|
(a) 290℃, 580℃ |
(b) 270℃, 580℃ |
(c) 270℃, 500 ℃ |
(d) 290 ℃, 540 ℃ |
P-type semiconductor is formed when
A. As impurity is mixed in Si B. Al impurity is mixed in Si
C. B impurity is mixed in Ge D. P impurity is mixed in Ge
|
(a) A and C |
(b) A and D |
(c) B and C |
(d) B and D |
