VITEEE 2015 :: Physics :: General questions

• Physics - General questions

To get an output  y=0 from the circuit shown in the figure, the input C  must be 

Answer:

Explanation:

As  we know, the output of OR gate

 Y=A+B

 The output of AND gate

 Y'= Y.C

$\Rightarrow$ Y'= (A+B). C

 if C=0 irrespective of A and B , then output Y must be zero

 The input resistance of a common emitter amplifier is 330 Ω and the load resistance is 5 k Ω. A change of base current is 15 μ A results in the change of collector current by 1 mA. The  voltage gain of the amplifier is 

Answer:

Explanation:

 Given,  $\triangle I_{C}= 1mA=10^{-3}$  A

 $\triangle I_{b}= 15\mu A=15\times 10^{-6} A$

 $R_{L}= 5k$ Ω =5 x 10³ Ω

 Ri= 330 Ω

 the voltage gain of an amplifier

 $A_{r}=\frac{\triangle I_{c}\times R_{L}}{\triangle I_{b}\times R_{i} }$

 = $\frac{10^{-3}\times5\times 10^{3}}{15 \times 10^{-6}\times330}=1010$

In the half-wave rectifier circuit operating with 50Hz  mains frequency.The  fundamental  frequency in the ripple will be

Answer:

Explanation:

The output is obtained for half-cycle only in half-wave rectifier. Therefore, frequency of the ripple is same as that of the input, 

i. e, 50 Hz

An n-type semiconductor is 

Answer:

Explanation:

The n-type semiconductor has an excess of free electrons for conduction. The total number of electrons in an atom is equal to the total number of protons in the nucleus. So, n-type semiconductor is neutral

Suppose a beam of electron  with each electron having energy E₀  incident on a metal  surface  kept in an evacuated chamber. Then

Answer:

Explanation:

The emitted  electrons may lie near the surface and can have a maximum amount of energy  E₀

 If they are from deep inside, then energy is less than E₀

• Physics - General questions