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In a photo emissive device and emission efficiency is increased by | |
A. | coating the cathode ray by an active materials [Correct Answer] |
B. | coating the cathode by an insulating material [Wrong Answer] |
C. | heating the cathode [Wrong Answer] |
D. | cooling the anode [Wrong Answer] |
View Answer
Explanation:-
Answer : A Discuss it below : !! OOPS Login [Click here] is required to post your answer/result |
Also Read Similar Questions Below :
⇒ If x = 0.1396 radians, the values of 1 - cos x and 2 sin^{2} (x / 2) using floating point arithmetic with a 4 digit mantissa are respectively
.1000 E - 1 each
.9727 E - 2 each
.1000 E - 1 and .9727 E - 2 respectively
.9727 E - 2 and .1000 E - 1 respectively
⇒ For H(s) to be positive real, the condition Re[H(jω)] ≥ 0 for 0 ≤ ω ≤ ∞ is
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a necessary condition
a sufficient condition
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0.43 Ω-m
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⇒ The V-I characteristic of a semi-conductor diode is shown in figure. From this figure it can be concluded
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⇒ The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T = 300 K, electronic charge = 1.6 x 10^{-19}C, thermal voltage = 26mV and electron mobility = 1350 cm^{2}
2.16 x 10^{4} A/cm^{2}
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6.48 x 10^{2} A/cm^{2}
⇒ A microstrip line has dielectric having relative permittivity ∈_{r}. The effective dielectric constant is
more than ∈_{r}
equal to 1
less than ∈_{r}
either a or b
⇒ For an antenna of height h_{t} metres, the radio horizon is equal to
4h_{t} metres
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⇒ A 0.5 μF capacitor is connected across a 10 V battery. After a long time, the circuit current and voltage across capacitor will be
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⇒ The Fourier series of an odd periodic function contains
odd harmonics only
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sine harmonics only
⇒ The main reason why Ni-Zn ferrites are used for audio and T.V. transformers is that
they have large saturation magnetization
they are easy to fabricate by rolling
they are totally free from pores and voids
they have a high electrical resistivity
⇒ The noise generated by a resistor depends upon
its operating temperature
its resistance value
both (a) and (b)
bandwidth
⇒ The symbol in figure is
UJT
PUT
SCS
SBS
⇒ In a megger the moving coil meter has a permanent magnet.
TRUE
FALSE
⇒ A cavity resonator is
a hollow metallic enclosure
a hollow enclosure having magnetic material as its walls
a hollow enclosure having dielectric material as its walls
either (b) or (c)
⇒ In brushless excitation system of modern alternators, the main exciter is
dc generator
ac generator
either dc or ac generator
induction generator
⇒ The output V_{0} in figur
-100 V
-100 mV
10 V
10 mV
⇒ When a plane wave is incident normally from dielectric '1' (μ_{0}, ε_{1}) onto dielectric '2' (μ_{0}, ε_{2}) the electric field of the transmitted wave is 2 times the electric field of the reflected wave. The ratio ε_{2}/ε_{1} is
0.5
1
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TRUE
FALSE
depend on distance
none
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⇒ GaAs has an energy gap 1.43 eV the optical cut off wavelength of GaAs would lie in the
visible region of the spectrum
infrared region of the spectrum
ultraviolet region of the spectrum
for ultraviolet region of the spectrum
⇒ The number of p-n junctions in a semiconductor diode are
0
1
2
1 or 2
⇒ Which of the following materials has the highest electrical conductivity?
Steel
Silver
Aluminium
Zinc
⇒ In a bipolar transistor which current is smallest
collector current
base current
emitter current
any of the three currents
⇒ If (225)_{Y} = (165)_{8} find value of Y
7
8
9
11
⇒ For a high pass filter, β = p in attenuation band.
TRUE
FALSE
⇒ In a two phase servomotor the two stator windings have a phase difference of
30°
45°
90°
135°
⇒ To multiply a number by 8 in 8085 we have to use
RAL
instructiononce
twice
thrice
four times
⇒ An op-amp uses
RC coupling
direct coupling
transformer coupling
either (b) or (c)
⇒ The dual of a link is
twig
node
loop
tree branch