The distance between the plates of a parallel plate condenser is 4mm and potential difference is 60 volts. If the distance between the plates is increased to 12mm, then
|
(a) The potential difference of the condenser will become 180 volts |
|
(b) The P.D. will become 20 volts |
|
(c) The P.D. will remain unchanged |
|
(d) The charge on condenser will reduce to one third |
(a) The potential difference of the condenser will become 180 volts
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An object is immersed in a fluid. In order that the object becomes invisible, it should
|
(a) Behave as a perfect reflector |
|
(b) Absorb all light falling on it |
|
(c) Have refractive index one |
|
(d) Have refractive index exactly matching with that of the surrounding fluid |
Identify the paramagnetic substance
|
(a) Iron |
(b) Aluminium |
(c) Nickel |
(d) Hydrogen |
If a diamagnetic substance is brought near north or south pole of a bar magnet, it is
| (a) Attracted by the poles |
| (b) Repelled by the poles |
|
(c) Repelled by the north pole and attracted by the south pole |
|
(d) Attracted by the north pole and repelled by the south pole |
The photoelectric threshold wavelength for potassium (work function being 2eV ) is
|
(a) 310 nm |
(b) 620 nm |
(c) 1200 nm |
(d) 2100 nm |
Isogonic lines on magnetic map will have
|
(a) Zero angle of dip |
(b) Zero angle of declination |
|
(c) Same angle of declination |
(d) Same angle of dip |
If a piece of metal was thought to be magnet, which one of the following observations would offer conclusive evidence
|
(a) It attracts a known magnet |
(b) It repels a known magnet |
|
(c) Neither (a) nor (b) |
(d) It attracts a steel screw driver |
A radio-isotope has a half- life of 5 years. The fraction of the atoms of this material that would decay in 15 years will be
|
(a) 1/8 |
(b) 2/3 |
(c) 7/8 |
(d) 5/8 |