IIT JAM Physics MCQ Test 11


30 Questions MCQ Test Mock Test Series for IIT JAM Physics | IIT JAM Physics MCQ Test 11


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This mock test of IIT JAM Physics MCQ Test 11 for Physics helps you for every Physics entrance exam. This contains 30 Multiple Choice Questions for Physics IIT JAM Physics MCQ Test 11 (mcq) to study with solutions a complete question bank. The solved questions answers in this IIT JAM Physics MCQ Test 11 quiz give you a good mix of easy questions and tough questions. Physics students definitely take this IIT JAM Physics MCQ Test 11 exercise for a better result in the exam. You can find other IIT JAM Physics MCQ Test 11 extra questions, long questions & short questions for Physics on EduRev as well by searching above.
QUESTION: 1

Chromium has BCC structure. Its atomic radius is 0.1249 nm. The free volume/ unit cell is

Solution:

Given data are
Atomic radius of chromium, r = 0.1249 nm.
Free volume/unit cell = ?
If 'a' is the BCC unit cell edge length, then the relation between a and 'r' is

Volume of unit cell. V = a3 = (0.28845)3 nm3
= 0.024 nm
Number of atoms in BCC unit cell = 2
Hence volum e o f a tom s in unit cell, 
Free volume/unit cell = V - v = 0.00767 nm3

QUESTION: 2

The separation of a {1 2 3} plane of an orthorhombic unit cell with a = 0 .8 2 nm, b = 0.94 and c = .75nm. is

Solution:

The separation of hkl plane is given as for an orthorhombic lattice s

 

QUESTION: 3

Consider a BCC crystal with lattice constant a’. Determine the no. of atoms per unit area in the ( 1 .1 . 1) plane if a = 1A0

Solution:

No. of atoms at vertex in (1. 1. 1) plane = 
No. of atoms at centre = 1
Total no. of atoms 
Area of plane 
No. of atoms per unit area in the 1 .1 . 1 plane = 

QUESTION: 4

What is the ratio of the nearest neighbour distance to the next nearest neighbour distance in a simple cubic crystal?

Solution:

We know, in a simple cubic lattice all atoms are at eight corners of cubic lattice of length a.
So, In a simple cubic lattice, the distance of nearest neighbour d1 = a and the distance of next nearest neighbour d1 = a√2

QUESTION: 5

What is the maximum radius of the sphere that can just fit into the void at the body centre of the fcc structure coordinated by the facial atom. Given r is the radius of atom

Solution:

The situation is shown in Fig. Let R be the radius of the sphere that can just fit into the void.
From figure,

4 + R = a/2
∴ R = (a/2) - r ..(1)
We know that for fee structure
a = 4 r / √2   ...(2)
Substituting the value of a from eq.(2) in eq. (1), we get

QUESTION: 6

Xenon crystallizes in fee lattice and the edge of the unit cell is 620 pm. then the radius of xenon atom is

Solution:

For fee lattice 4r = √2 * a. where a = 620 pm
or r = 1/2 √2 a 
1/2 √2 x 620 pm = 219.20 pm

QUESTION: 7

Determine the M. I. of a plane that makes intercepts of on the co-ordinate axes of an orthorhombic crystal with a:b:c = 4:3:2

Solution:

Here the unittranslations are a = 4, b = 3 andc = 2 following the same procedure
i) Intercepts 2 3 4
ii) Division by unit translation   
iii) R eciprocals 2 1  1/2
iv) After clearing fraction 4 2 1
Therefore the Miller indices of the plan is (421)

QUESTION: 8

The rock salt (NaCI) has fcc structure and contains 4 molecules per unit cell. Calculate the lattice constant for the crystal.
Molecular weight of NaCI = 58.45 kg/kmol
Density = 2180 kg/m3
Avogadro Number NA = 6.02 * 1026 kmol-1

Solution:

QUESTION: 9

Which of the following output curve is correct for the given circuit.

Solution:

diode Dis always reverse biased 
Then V-5V (for the complete cycle)

QUESTION: 10

The current following through (RL = 5kΩ). if the zener diode used in the circuit has rating of 10 V:-

Solution:

Voltage across RL = 10V. 
RL=5kΩ

QUESTION: 11

The concentration of holes in Silicon semiconductor incorrectly the represents the variation with the following parameters as :

Solution:


Then we can clearly see that “E1" affects the concentration of holes in a Semiconductor.

QUESTION: 12

Find the ratio of intercepts on the crystal axes by plane (231) in a simple cubic lattice.

Solution:

Let x1. x2, x3 be the intercepts by the plane on the axes. In terms of axial units the intercepts are

where m, n. p are numbers.
Now  
m : n : p 
= 3 : 2 : 6 
X: X2 : X3 = 3 : 2 : 6

QUESTION: 13

Find the output voltage in gives fig.

Solution:

Determine the output voltage in Fig.


= - (0.9) 10 = - 9V

QUESTION: 14

A zener diode in the circuit shown in the figure below, has a knee current of 5 mA. and a maximum allowed power dissipation of 330 mW. What are the minimum and maximum load currents that can be drawn safely from the circuit, keeping the output voltage V0 at 6V?

Solution:


Maximum load current = (60 - 5) m 
A = 55mA
Now,

lL min = 60 mA - 50 mA = 10mA

QUESTION: 15

Silicon diode is less suited for low voltage rectifier operation, because

Solution:

Silicon diode is less suited for low voltage rectifier operation because its breakdown voltage is high.

*Multiple options can be correct
QUESTION: 16

In a single state C.E. amplifier using battery supply. Vcc = -20 V and the transistor has a minimum β value of 20 and Ico = 10 μA. Quiescent point at Vce = 6V and Ic= 2mA if Rc = 4 kΩ. Choose the correct statement

Solution:

Here


Now
IC = IB + IC
= 0.1mA + 2mA = 2.1 mA
If Ve be the voltage across Re. then


Now

Let I1, and l2, be the currents in resistors R1, and R2 and l2 = 10 I\b

Now

and

Hence 

*Multiple options can be correct
QUESTION: 17

For this circuit Vz = 10 V, R = 1 kΩ and lZmax = 2.5 mA. If VL is maintained at 10 V. choose the correct statement :-

Solution:

*Multiple options can be correct
QUESTION: 18

Figure show that a silicon transistor with β = 100 is biased by the resistor method. Which of the following statements are correct?

Solution:




This locates the first point.
When Vce = 0,

This located the second point.
A line joining the above two points is known as d.c. load line as shown in fig. (b)
(ii) Operating point Q.
We know that in a silicon transistor Vbe = 0.7 volt

∴ 
∴ Collector current 

Now

So operating point is 6 volt 1 mA.

*Multiple options can be correct
QUESTION: 19

An NPN transistor circuit shown in the following figure has
∝ = 0.985


Which of the following statements are correct?

Solution:

Here α = 0.985

We know

∴ β = 66
Base current. 
Voltage across R2 is given by

Voltage across R1 is given by

Current flowing through R1 and R2


∴ Resistance, R1 =  
Voltage across Rc = Vcc - Vce - Ve
= 20 - 5 - 2 x 2 = 11 volt
Collector resistance, 

*Multiple options can be correct
QUESTION: 20

Choose the correct statement for the given output-amp circuit.

Solution:

Voltage at inverting terminal Vx = 1 volt (a s non inverting terminal is al 1 V )
Vp = 2 volt
At node X :

or VY = 0
At node P:

or V0 = 4 volt.

*Answer can only contain numeric values
QUESTION: 21

Electrons are accelerated to 344 volts and are reflected a crystal. The first reflection maximum occurs when glancing angle is 600. The spacing of the crystal is_____
Planck's constant, h = 6.62 * 10-34 joule-sec.
Charge on election, e = 1.6 * 10-19 coul. 
mass of the election , m = 9 * 10-31 kg


Solution:

The de-Broglie wavelength associated with electrons is given by
 (∴ E = e V joule)
∴ 
According to Bragg’s law.

Substituting the values, we get

= 0.38 x 10-10 m = 0.38 

*Answer can only contain numeric values
QUESTION: 22

At very low temperature the specific heat of rock salt varies with temperature according to Debye's T3 law

θD for rock salt is 231 K ._____ J heat is required to raise the temperature of 2K mol of rock salt from 10 to 50 K.


Solution:

272000
Heat required to raise the temperature of 2 K mol. of salt through temperature of dT
dQ = mC dT   (∴ m = 2 K mol)

Hence total heat required to raise the temperature from 10K to 50K is

substituting the values we have

*Answer can only contain numeric values
QUESTION: 23

Mobilities of electrons and holes in a sample of intrinsic germanium at 300K are 0.36 m2V-1 S-1 and 0.17m2V-1S-1 respectively. If the conductivity of the specimen is 2.12 Ω-1 m-1, then the forbidden energy gap is _____ eV.


Solution:

0.720
Conductivity of an intrinsic semiconductor is given by 

or

= 2.5 x 1019 / m3
But

for C = 4.8 x 1021
and kBT = 1.38 x 10-23 x 300J = 
We have

or

and
Eg = 2 x 13.8 x 0.025875 = 0.720 eV.

*Answer can only contain numeric values
QUESTION: 24

A semiconductor has an electron concentration of 0.45 x 1012 m-3 and a hole concentration of 5.0 x 1020 m3. Its conductivity is _________ Sm-1. Given electron mobility = 0.135 m2 V-1 s-1; hole mobility = 0.048 m2 V-1 s-1.


Solution:

The conductivity of a semiconductor is the sum of the conductivities due to electrons and holes and is given by 

As per given data ne is negligible as compared to nh so that we can write 

where S (seamen) stands for Ω-1.

*Answer can only contain numeric values
QUESTION: 25

For copper at 1000 K, the energy will be _____ eV at which the probability F(E) that a conduction electron state will be occupied is 0.90. (EF = 7 eV)


Solution:

The probability F(E) of a state corresponding to energy E being occupied by an electron temperature T is given by

There fore 
or 
Thus

For copper, EF = 700 eV
so that E = EF + ΔE = 7.00 eV - 0.19 eV = 6.81 eV

*Answer can only contain numeric values
QUESTION: 26

The given figure shows a silicon transistor connected as a common emitter amplifier. The quiescent collector voltage of the circuit is approximately______V.


Solution:

*Answer can only contain numeric values
QUESTION: 27

A p-n junction diode in series with a 100 ohms resistor is forward biased so that a current of 100 mA flows. If the voltage across this combination is instantaneously reversed to 10 V at t = 0. the reverse current that flows through the diode at t = 0 is approximately________ mA.


Solution:

Reverse current at t = 0 when the voltage

is instantaneously reversed to - VR = - 10 V is

Negative sign indicating reversal of current and voltage.
∴ 

*Answer can only contain numeric values
QUESTION: 28

The 6V zener diode shown in the figure, has zero zener resistance and a knee current of 5mA. The minimum value of R so that the voltage across it does not fall below 6 V i s _________ ohms.


Solution:

Output voltage is regulated to the zener voltage 6V.

Zener diode current, lZK = 5 mA
This is the minimum current drawn by zener.
Hence the load current lL will be maximum.
∴ IL,max = 80 - 5 = 75mA
∴ 

*Answer can only contain numeric values
QUESTION: 29

A voltage source VAB = 4 sin ωt is applied to the terminal A and B of the circuit shown in the given figure. The diodes are assumed to be ideal. The impedance by the circuit across the terminal A and B is __________ kΩ.


Solution:

Diode D1 conducts through 10 kΩ on the extreme right and diode D2 is blocked. Diode D2, conducts through the 10k Ω in the middle branch and diode D1 is blocked. Thus the source always sees a resistance of 10 kΩ.

*Answer can only contain numeric values
QUESTION: 30

A transistor with β = 45, is used with collector to base biasing with a quiescent value of 5 volt for Vce . If Vcc = 24 volt, Rc = 10 kΩ and Re = 270 ohm. The value of Rb is kΩ.


Solution:


Applying Kirchoff s low to collector-emitter circuit, we have

or 24 = (1 +45) lb (10 - 103 x 270)+ 5 
or 19 = 46 lb [10.27 x 103]
or 

∴ 
From the figure 

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