- AExist everywhere.
- BExist only in the immediate vicinity of electric charges.
- CExist only when both positive and negative charges are near one another.
- DAre imaginary.
Explanation:
Electric lines of force are imaginary.
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The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength λ for sodium is
, the value of λ for tungsten is
|
(a) 5893 Å |
(b) 10683 Å |
(c) 2791 Å |
(d) 528 Å |
A magnet is placed in iron powder and then taken out, then maximum iron powder is at
|
(a) Some away from north pole |
(b) Some away from south pole |
|
(c) The middle of the magnet |
(d) The end of the magnet |
The image of an extended object, placed perpendicular to the principal axis of a mirror, will be erect if:
Two bulbs of 500 watt and 200 watt are manufactured to operate on 220 volt line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are joined in parallel and secondly in series, will be
|
(a) |
(b) |
(c) |
(d) |
Light travels through a glass plate of thickness t and having refractive index n. If c is the velocity of light in vacuum, the time taken by the light to travel this thickness of glass is
|
(a) |
(b) tnc |
(c) |
(d) |
A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will
|
(a) Get deflected vertically upwards |
|
(b) Move in a circular orbit with its speed increased |
|
(c) Move in a circular orbit with its speed unchanged |
|
(d) Continue to move due east |
The respective radii of the two spheres of a spherical condenser are 12 cm and 9 cm. The dielectric constant of the medium between them is 6. The capacity of the condenser will be
|
(a) 240 pF |
(b) 240 μF |
(c) 240 F |
(d) None of the above |
The plate characteristic curve of a diode in space charge limited region is as shown in the figure. The slope of curve at point P is 5.0 mA/V. The static plate resistance of diode will be
| (a) 111.1W | (b) 222.2W | (c) 333.3W | (d) 444.4W |