GATE Physics Mock Test Series - 5 - Physics MCQ

# GATE Physics Mock Test Series - 5 - Physics MCQ

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## 60 Questions MCQ Test GATE Physics Mock Test Series 2025 - GATE Physics Mock Test Series - 5

GATE Physics Mock Test Series - 5 for Physics 2024 is part of GATE Physics Mock Test Series 2025 preparation. The GATE Physics Mock Test Series - 5 questions and answers have been prepared according to the Physics exam syllabus.The GATE Physics Mock Test Series - 5 MCQs are made for Physics 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for GATE Physics Mock Test Series - 5 below.
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GATE Physics Mock Test Series - 5 - Question 1

### In the hydrogen atom spectrum, the ratio of the energy for the transition n = 3 → n = 1 to that of n = 4 —>n = 1 is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 1

Ratio of energy of transition n = 3 → n = 1 t o that of n = 4 → n = 1 is

GATE Physics Mock Test Series - 5 - Question 2

### The 32P radio isotope used in leukemia theraphy has t1/2 = 14.26 days, what % of 32P remains after 35 days

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 2

Time t = n x t1/2
35 = n x 14.26
No.of half lives,

= 100 x 0.1824
N = 18.24%

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GATE Physics Mock Test Series - 5 - Question 3

### The wave function ψ of a quantum mechanical system described by a Hamiltonian  can be written as a linear combination of φ1and φ2 which are the eigen functions of H with eigen values E1 and E2 respectively . At t = 0, the system is prepared in the state and then allowed to evolve with time. The wave function at time t =  will be

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 3

So, wavefunction at time

GATE Physics Mock Test Series - 5 - Question 4

An engine absorb heat at a temperature of 1000 K and rejects heat at 600 K. If the engine operates at maximum possible efficiency, the amount of work performed by the engine for 2000 J heat input is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 4

Maximum possible efficiency =
Heat input W = 2000 x 0.4 = 800 J

GATE Physics Mock Test Series - 5 - Question 5

One mole of a perfect gas is heated at a constant pressure of 1 atm from 0°C to 100°C. What is the change in internal energy?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 5

Change in internal energy at constant pressure

GATE Physics Mock Test Series - 5 - Question 6

For an assembly of molecules (molar mas = M) at temperature T, the standard deviation of maxweller’s speed is approximately

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 6

Root mean square velocity
Average velocity
standard deviation of the molecular speeds

GATE Physics Mock Test Series - 5 - Question 7

Two uniform thin rods of equal length 2L and masses M1 and M2 are joined together along the length. The moment of inertia of the combined rod of length 4L about an axis passing through the mid point and perpendicular to the length of the rod is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 7

Moment of inertia of uniform rod about an axis passing through the end and perpendicular to the length of rod is

GATE Physics Mock Test Series - 5 - Question 8

A particle is constrained in a one-dimensional box of length 2a with potential

Energy difference between level n = 3 and n = 2 is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 8

Energy of a particle in one dimensional box

Given that n = 2, L = 2a
&
When, n = 3 and I = 2a

GATE Physics Mock Test Series - 5 - Question 9

A person of mass m stands at one end of a plank of mass M and length L. the plank is lying on a smooth horizontal surface, what is distance moves by the plank as the person walks on it to reach the other end.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 9

In the given system there is no external force acts along the horizontal surface. Then the centre of mass co - ordinate remains same along to horizontal surface.

GATE Physics Mock Test Series - 5 - Question 10

A particle of mass m is located in a unidimensional potential field where the potential energy of the particle depends on the coordinate x as U(x) = U0 (1 - cos a x ) ; U0 and a are constants. Then the period of small oscillations that the particle performs about the equilibrium position.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 10

U(x) = U0 (1 - cos ax)

F(x) = - U0 a sin ax
∴F(x) = 0

So, x = 0 is stable equilibrium position.
The small force arising due to this small displacement is

So, this is the condition of S.H.M. motion so. A = -ω2 Δx so to compare

GATE Physics Mock Test Series - 5 - Question 11

If the electrostatic potential at point (x,y) is given by V (x,y) = [ 4x + 9y] volts, the electrostatic energy density at that point (in J/m3) is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 11

Given V(x, y) = 4x + 9y

GATE Physics Mock Test Series - 5 - Question 12

A solid sphere of mass m callides head on with identical sphere at rest. If the coefficient of restitution is e. The loss in kinetic energy

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 12

Let u be the velocity of a moving sphere before collision and v1 and v2 be the velocities of the two sphere after collision.

form conservation of momentum we get
mu = mv+ mv2
v1+ v2 = u

Loss in kinetic energy = KEf - KEi

GATE Physics Mock Test Series - 5 - Question 13

An insulated gas jar of mass M which is equal to the molecular mass of the enclosed gas moves with certain K. E. when the jar is stopped, the increment of temperature of the gas is  ΔT. The K .E . of the system before stopping is , where  adiabatic exponent of the gas.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 13

The disordered K.E. of the gas converts into the internal energy of its. Hence,

K.E. of the system

GATE Physics Mock Test Series - 5 - Question 14

The input in the below circuit to get output one is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 14

The set of input is (1, 1, 1).

GATE Physics Mock Test Series - 5 - Question 15

If the amplitude of a damped - oscillator becomes one - third in 2 minutes, what will be the amplitude of oscillation as compared to initial one after 6 minutes ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 15

In case of damped oscillations, amplitude decrease exponentially with time , i.e

GATE Physics Mock Test Series - 5 - Question 16

The relation between angular frequency ω and wave number K for given type of waves is . The wave number K0 for which the phase velocity equals the group velocity is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 16

Dispersion relation

....(1)
Given Vg = Vphase

2w2 = a K + 9b K3
2a K + 6b K3 = a K + 9b K3
a K = 3 b K3

GATE Physics Mock Test Series - 5 - Question 17

A ray of light passes through four transparent media with refractive indices μ123 and u4 as shown in Fig. The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 17

The emergent ray will be parallel to the incident ray provided the refractive index of the medium of incidence is the same as the refractive index of the medium of emergence. Thus μ4 = μ1

GATE Physics Mock Test Series - 5 - Question 18

For a pure substance, the slope of the plot of Gibbs free energy (G) against T at constant pressure is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 18

We know gibbs free energy
G = U + PV - TS

= Tds - pdV + pdV + vdP - Tds - sdT
dG = VdP - SdT
(dG)p = -SdT

So, slope of this curve is - S.

GATE Physics Mock Test Series - 5 - Question 19

The space - time coordinates of two events as measured by O are x1= 6 x 104 m,y1 = z1 = Om, t1’ = 2 x 104sec and x2= 12 x 104m, t2= 1 x 10-4sec. What must be the velocity of O’ with respect to O if O’ measures the two events to occur simultaneously ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 19

Subtracting two Lorentz transformation.
If the events are simultaneous in the O’ frome of refrence the t1’ = t2

On solving , we obtain,

Therefore , v is in the negative x - direction.

GATE Physics Mock Test Series - 5 - Question 20

are the Pauli matrices. The expression equal to

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 20

We know that the Pauli matrices are given as

GATE Physics Mock Test Series - 5 - Question 21

The electric field component of a plane electromagnetic wave travelling in vacuum is given by The Poynting vector for the wave is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 21

We know that

Poynting vector for the wave

GATE Physics Mock Test Series - 5 - Question 22

The x-y plane is the boundary between free space and a magnetic material with relative permeability μ. The magnetic field in the free space is  The magnetic field in the magnetic material is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 22

According to boundary condition

The magnetic field in the magnetic material is

GATE Physics Mock Test Series - 5 - Question 23

An infinite, conducting slab kept in a horizontal plane carries a uniform charge density σ . Another infinite slab of thickness t, made of a linear dielectric material of dielectric constant K, is kept above the conducting slab. The bound charge density on the upper surface of the dielectric slab is _______ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 23

Electric field due to infinite, conducting slab inside the dielectric is
Polarization

GATE Physics Mock Test Series - 5 - Question 24

Two parallel plates of a capacitor, separated by 2 mm, are at a potential difference of 20V. A dielectric sheet of dielectric constant 2 and thickness 1 mm is inserted between the plates. How does the potential difference between the two plates change ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 24

Initially the capacitance was given by
Now after introduction of dielectric slab of thickness t and dielectric constant k the capacitances are both are connected series then as in series combination resultant capacitance will be c

Now charge will remain same.
Hence, initially potential  and after introduction of slab

GATE Physics Mock Test Series - 5 - Question 25

If waves in an ocean travel with a phase velocity then what is the group velocity Vg of the ‘wave packet’ of these waves ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 25

The phase velocity
where λ wavelength
Phase velocity

Group velocity =

GATE Physics Mock Test Series - 5 - Question 26

A transistor with β = 100 is used in C E configuration.The collector circuit resistance is 1k Ω & Vcc = 20v. Assuming Vbe = 0. Find the value of collector to base resistance such that quiescent collector emitter voltage is 4V.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 26

Rb = 25 kΩ

GATE Physics Mock Test Series - 5 - Question 27

Calculate the collector current in Voltage divider method with the following data

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 27

GATE Physics Mock Test Series - 5 - Question 28

(110011.11)2 is written in decimal form as

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 28

(110011.11 ) = (1 x 25) + (1 x 24) + (1 x 21) + (1 x 2o) + (1 x 2-1) + (1 x 2-2
= 32 + 16 + 2 + 1 + 0.5 + 0.25 = 51.75

GATE Physics Mock Test Series - 5 - Question 29

A truth table is given as, then the correct logic expression corresponding to it is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 29

GATE Physics Mock Test Series - 5 - Question 30

In in the Op-amp circuit V0 is given by

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 30

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 31

A mass m, moves in a circular orbit of radius r0 under the influence of a central force whose potential is  Then

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 31

Under central force, effective potential is

A circular orbit is possible at the value of r for which

and stable if

which is possible only if (n + 1) < 3  ⇒ n < 2

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 32

A series of sine and cosines of multiples x; which will represent x + x2 in the interval -π < x < π then

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 32

The Fourier series of given function f(x) = x + x2

where

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 33

Which of the following are statement is/are correct :-

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 33

In case of boiling, V2 represents the specific volume of the vapour and Vthat of the liquid phase of the substance.
For all substance the specific volume in vapour phase is always larger than that in the liquid phase.

Hence, in the case of the boiling point of a liquid an increases in the pressure (dP > 0) will give a positive value of dT.
It means the boiling point is raised by an increase in pressure.

The melting point of substance, which expands on melting increases with increase of pressure.
(V2 - V1) < 0
Melting point of substance which contracts on melting, decreases with increases of pressure.

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 34

Consider the following statements regarding the magnitude of barrier potential of a p-n junction. Which of the following statements is/are Correct ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 34

When a p type semiconductor having holes as majority Carriers is clamped with a n-type semiconductor having e- as majority Carriers same efrom n - side goes to p- side & same holes goes to n - side ; thus created a potential barrier. Which ;
(i) Depends on temp.
(ii) Depends on fermi level.
(iii) Forbidden Energy gap (Eg)
(iv) Majority Carriers.
thus ; correct options are (B,C,D).

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 35

Consider the following statements related to an oscillator; Among these statements which of the following are Correct ?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 35

As an oscillator is a system consisting of active & passive Circuit elements to produce a sinusoidal or other, respective wave forms at the output within the amplification of an external source (signal). It transformers the DC power from the source to the AC power in the load.
This Consists of positive feedback amplifier & has noise as the initial signal & Consists of a freq. signal selector.

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 36

A Carnot engine operating between two temperatures 727°c and 27°c is supplied heat energy at the rate of 500 Joule / cycle. Sixty percent of the work output is used to drive a refrigerator, which reject heat to the surrounding at 27°c. If the refrigerator removes 1050 Joule of heat per cycle from the low temperature reservoir. Then

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 36

Efficiency
Work output = ηQ
0.7 x 500 = 350 J
In refrigeration Q1 +w = Q2
work input = 60% of work output of heat engine = 0.6 x 350 = 210 J
Q1 Heat removed Q1 = 1050 J
Q2Heat rejected Q2 = Q1+ w = 1050 + 210 = 1260 J
Q2= Q1+ w = 1050 + 210 = 1260 J

T1 = 250 K

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 37

An ideal diatomic gas at pressure pi and volume vi double its volume adiabatically. Then

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 37

V For diatomic gas V =1.4
Final volume =2x initial volume
Vf = 2Vi

Work done by the gas

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 38

Two holes 1 and 2 are made at depths h and 16h respectively. Both the holes are circular but radius of hole 1 is two times that of hole 2

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 38

After some time V1 and V2 both will decrease, but decrease in the value of V1 is
more dominating. So

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 39

A rocket of enitial mass m0 is ejecting gas at the constant rate α and a constant velocity v0 with respect to it and that it moves vertically upward in a constant gravitational field. Then the velocity of rocket v and travelled distance by the rocket x is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 39

Gas ejected at constant rate α > o
then m = m0 - αt

General equation for rocket is

At t = 0, v = 0

at t = 0, x = 0

*Multiple options can be correct
GATE Physics Mock Test Series - 5 - Question 40

For a scalar function φ satisfying the Laplace equation ,  has

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 40

By the Laplace equation

OR Divergence of  is zero.
And

GATE Physics Mock Test Series - 5 - Question 41

In a certain inertial frame two light pulses are emitted at point 10 km apart and separated in time 10 ms. An observer moving at a speed V along the line joining these points notes that the pulses are simultaneous. Therefore V is_____(in C).

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 41

Space and time coordinates of two pulses are x= 0, t1 = 0 for first pulse
x2 = 10 x 103 m, t2 = 10 x 10-6 sec for second pulse.
For an observer moving with velocity V

Two pulse will be simultaneous. If

GATE Physics Mock Test Series - 5 - Question 42

Let  be orthonormal functions . Find the value of n which normalise the function

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 42

Normalization condition f = 1

n2[1 + 4] = 1

⇒

GATE Physics Mock Test Series - 5 - Question 43

Rank of matrix is _________ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 43

We have |A| = 1(24 - 25) - 2(18 - 20) + 3(15 - 16) = 0
Therefore, the rank of A is less than 3. Now there is at least one minor of A order
2, namely
Which is not equal to zero.
Hence the rank of matrix is 2.

GATE Physics Mock Test Series - 5 - Question 44

The number of independent solutions of the equation

are _______ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 44

Let y = emx is a solution of equation

(m2 - 3m + 2)emx = 0
m2 - 3m + 2 = 0 ⇒m = 1, 2
The two independent solutions are
y = e2x and ex

GATE Physics Mock Test Series - 5 - Question 45

A planet is revolving around a star in an elliptic orbit. The ratio of the farthest distance to the closest distance of the planet from the star is 4. The ratio of kinetic energies of the planet at the closest to farthest position is ______ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 45

Angular momentum is conserved during revolution of planet, because gravitational force is a central force,
m r1 v1 = m r2v2
or since L is constant hence

GATE Physics Mock Test Series - 5 - Question 46

Steam at 100°C is mixed with 1500 grams of water at 15°C so that the final temperature of the mixture is 80°C. The mass of steam is _____ .(in grams)

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 46

m2 = 1500 gms
T1 = 373 K
T2 = 288 K
The final temperature of the mixture be T
T = 273 + 80 = 353 K
m1 x 540 + m1(373 - 353) = 1500(353 - 288)
(540 + 20)m1 = 1500 x 6.5
m1 = 175 gm

GATE Physics Mock Test Series - 5 - Question 47

The mean free path of the particles of a gas at a temperature T0 and pressure P0 has a value λ1 . If the pressure increased to 1.5 P0 and the temperature is reduced to 0.75 T0.  Then   = _____ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 47

The mean free path

GATE Physics Mock Test Series - 5 - Question 48

A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same train. Find out the ratio of the velocity of train B to that of train A.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 48

Here, the observer is moving towards this stationary source.
In first case, n' = n
∴
In second case, n ” = n
∴ From eq. (1)
From eq. (2)
∴

GATE Physics Mock Test Series - 5 - Question 49

Find out the rms value of the emf given by E = 8 sin ωt + 6 sin 2 ωt volt?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 49

= 32 + 18 + 0
= 50

GATE Physics Mock Test Series - 5 - Question 50

Unpolarised light of intensity l0 gets polarised as it emerges from a polarizer. It then passes through an analyser. The intensity of light emerging from the analyser is Find out the angle between the polarising direction of the polarizer and analyser (in degree)?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 50

Average of

So, intensity of unpolarised light then intensity of polarised light coming out from polarizer is

from malaus law

⇒

GATE Physics Mock Test Series - 5 - Question 51

If each square cm, of sun’s surface radiates energy at the rate of 1.5 x 103 cal. sec-1cm-2 and Stefan’s constant is 5.7 x 10-8 joule sec-1 .m-2(K)-4. Find out the temperature of the sun’s surface in degree Celsius?

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 51

From Stefan-Boltzmann’s law

If T » T0 (as in this case) then we have
...(1)

∴    Substituting these values in equation (1), we get

GATE Physics Mock Test Series - 5 - Question 52

Find out the minimum number of AND GATE require to solve the logic expression

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 52

y = AC (1+B)
y = AC i.e 1.

GATE Physics Mock Test Series - 5 - Question 53

A ball impinges directly into another ball at rest by the impact, if half of the initial kinetic energy is destroyed in the collision, find the coefficient of restitution.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 53

Let m be the mass of the first ball and u its velocity immediately before impact. M the mass of 2nd ball and V its velocity after impact. Then from the principle of conservation of momentum and by newton’s law impact, we get
MV = mu
and V = eu ....(1)
It is given in the problem energy lost = half the initial energy
or

or
Simplifying we get

GATE Physics Mock Test Series - 5 - Question 54

10 gm. of steam at 100°C is blown into 90 gms. of water at 0°C contained in a calorimeter of water equivalent 10 gms. The whole of the steam is condensed. Calculate the increase in the entropy of the system, (in cal/K)

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 54

Given m1 = 10 gm., T1= 100°C = 373 K
m2 = 90 + 10 = 100 gm., T2 = 0°C = 273 K.
Let the final temperature be T K.
10 x 540 + 10 (373 - T) = 100 (T - 273)
T = 331.2 K.
Now (i) Change in entropy when temperature of water and calorimeter increases from 273 K to 331.2 K.

(ii) Change in entropy when 10 gms. steam at 373 K condenses to water at the same temperature

(iii) Change in entropy when 10 gm. water is cooled from 373 K to 331.2 K.

or dS3 = - 1.188 cal/K
The net change (or increase in entropy)
dS = dS1 + dS2 + dS3= + 19.324 - 14.477 - 1.188 = + 3.659 cals./K.

GATE Physics Mock Test Series - 5 - Question 55

The value of the magnetic field required to maintain non - relativistic protons of energy 1 MeV in a circular orbit of radius 100mm is _____Tesla.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 55

GATE Physics Mock Test Series - 5 - Question 56

A point charge is placed between two semi- infinite conducting plates which are inclined at an angle of 60º with respect to each other. The number of image charges is ______ .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 56

GATE Physics Mock Test Series - 5 - Question 57

A solid sphere of Radius R has a charge density, given by

where r is the radial co-ordinate and p0, a and R are positive constants. If the magnitude of the electric field at r =  is 1.25 times that at r = R, then the value of a is

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 57

GATE Physics Mock Test Series - 5 - Question 58

40-0-40 volt (rms) transformer is used with a full wave rectifier circuit with each diode having internal resistance of 1Ω . If load resistance is 19Ω then the dc load current is _______________________ (in Amperes ) .

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 58

GATE Physics Mock Test Series - 5 - Question 59

The current flowing through a certain P-n junction at room temperature when reverse-biased (bias voltage being very large in comparison to VT) is 0.15μA. Determine the current (in μA) flowing through the diode when applied voltage is 0.12V. (VT = 26 mV)

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 59

Large reverse bias current - (I0)= 0.15 x 10-6 A
V = 0.12V & VT = 26 mV = 0.026 V.

GATE Physics Mock Test Series - 5 - Question 60

An operational amplifier with negative feedback has voltage gain of 150. It is found that without feedback, an input signal of 50 mV is required to produce a given output; where as with feedback, the input signal must be 0.5V for the same output calculate the value of β.

Detailed Solution for GATE Physics Mock Test Series - 5 - Question 60

The gain with feedback (Af) of the amplifier is 150.
The input voltage required to produce same output voltage as for the amplifier without feedback is 0.5v.
The output will be (V0) =AF.Vi= 150x0.5 = 75V.
If no feedback is employed the required input to produce 75V is 50mV = 0.05V. Hence, the internal gain of the amplifier is :-

Now from

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