The current in a triode at anode potential 100 V and grid potential – 1.2 V is 7.5 mA. If grid potential is changed to – 2.2 V, the current becomes 5.5 mA. the value of trans conductance (gm) will be
|
(a) 2 mili mho |
(b) 3 mili mho |
(c) 4 mili mho |
(d) 0.2 mili mho |
(a) 2 mili mho
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An antenna is a device
|
(a) That converts electromagnetic energy into radio frequency signal |
|
(b) That converts radio frequency signal into electromagnetic energy |
|
(c) That converts guided electromagnetic waves into free space electromagnetic waves and vice-versa |
|
(d) None of these |
$\text{P}_0$
$\text{P}_0+ \frac{2\text{S}}{\text{r}}$
$\text{P}_0- \frac{2\text{S}}{\text{r}}$
$\text{P}_0- \frac{4\text{S}}{\text{r}}$
What was the fissionable material used in bomb dropped at Nagasaki (Japan) in the year 1945 ?
|
(a) Uranium |
(b) Nepturium |
(c) Berkalium |
(d) Plutonium |
In Young's double slit experiment, the distance between the two slits is 0.1 mm and the wavelength of light used is 4
. If the width of the fringe on the screen is 4 mm, the distance between screen and slit is
|
(a) 0.1 mm |
(b) 1 cm |
(c) 0.1 cm |
(d) 1 m |
A virtual image larger than the object can be obtained by
|
(a) Concave mirror |
(b) Convex mirror |
(c) Plane mirror |
(d) Concave lens |
The wavelength of the energy emitted when electron come from fourth orbit to second orbit in hydrogen is 20.397 cm. The wavelength of energy for the same transition in 
is
|
(a) |
(b) |
(c) |
(d) |
The two metallic plates of radius r are placed at a distance d apart and its capacity is C. If a plate of radius r/2 and thickness d of dielectric constant 6 is placed between the plates of the condenser, then its capacity will be
|
(a) 7C/2 |
(b) 3C/7 |
(c) 7C/3 |
(d) 9C/4 |
Which one of the following devices makes use of the electrons to strike certain substances to produce fluorescence
|
(a) Thermionic valve |
(b) Photoelectric cell |
|
(c) Cathode ray oscilloscope |
(d) Electron gun |
