Explore topic-wise MCQs in Electronic Devices Circuits.

This section includes 61 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices Circuits knowledge and support exam preparation. Choose a topic below to get started.

1.

Which of the following represents the best definition for the diffusion length for holes?

A. Average distance which an electron is injected travels before recombining with an electron
B. Average distance which a hole is injected travels before recombining with an electron
C. Average distance which a hole is injected travels before recombining with a hole
D. Average distance which an electron is injected before recombining with a hole
Answer» C. Average distance which a hole is injected travels before recombining with a hole
Discussion
2.

What is the diffusion length for electrons when Dn=10cm2/s and τn=40s?

A. 50cm
B. 25cm
C. 20cm
D. 15cm
Answer» D. 15cm
Discussion
3.

What is the diffusion length for holes when Dp=25cm2/s and τp=25s?

A. 25cm
B. 1cm
C. 0.04cm
D. 50cm
Answer» B. 1cm
Discussion
4.

The current entering the volume at x is I and leaving is I+Δi , the number of coulombs per second will be equal to δI. Is it true or false?

A. True
B. False
Answer» B. False
Discussion
5.

Calculate the number of coulombs per second if the area is 4cm2, recombination rate of hole is 1000 cm-3/s and the differential length is 2mm.

A. 1.28*10-23
B. 1.28*10-22
C. 1.28*10-21
D. 1.28*10-20
Answer» C. 1.28*10-21
Discussion
6.

What does p/τ represent?

A. holes
B. time
C. holes per second lost
D. p per unit time
Answer» D. p per unit time
Discussion
7.

On equating the generic form of current density equation and the point form of Ohm’s law, we can obtain V=IR. State True/False.

A. True
B. False
Answer» B. False
Discussion
8.

Calculate the potential when a conductor of length 2m is having an electric field of 12.3units.

A. 26.4
B. 42.6
C. 64.2
D. 24.6
Answer» E.
Discussion
9.

Find the resistance of a cylinder of area 200 units and length 100m with conductivity of 12 units.

A. 1/24
B. 1/48
C. 1/12
D. 1/96
Answer» B. 1/48
Discussion
10.

Find the current when the charge is a time function given by q(t) = 3t + t2 at 2 seconds.

A. 3
B. 5
C. 7
D. 9
Answer» D. 9
Discussion
11.

If the system is in steady state, it is in an equilibrium state.

A. True
B. False
Answer» C.
Discussion
12.

Mass can neither be created nor be destroyed is the principle of_______

A. Energy equation
B. Momentum equation
C. Continuity equation
D. Bernoulli’s principle
Answer» D. Bernoulli’s principle
Discussion
13.

When Reynold’s number limits to infinity, inviscid flow is approached.

A. True
B. False
Answer» B. False
Discussion
14.

Continuity equation is related to _______

A. Mass conservation
B. Energy conservation
C. Momentum conservation
D. Velocity change
Answer» B. Energy conservation
Discussion
15.

In a water supply system, water flows in from pipes 1 and 2 and goes out from pipes 3 and 4 as shown. If all the pipes have the same diameter, which of the following must be correct?

A. the sum of the flow velocities in 1 and 2 is equal to that in 3 and 4
B. the sum of the flow velocities in 1 and 3 is equal to that in 2 and 4
C. the sum of the flow velocities in 1 and 4 is equal to that in 2 and 3
D. the flow velocities in 1 and 2 is equal to that in 3 and 4
Answer» B. the sum of the flow velocities in 1 and 3 is equal to that in 2 and 4
Discussion
16.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ay2 + bxy and v = ax2 + bxy. The flow will be continuous if

A. a + b = 0
B. a – b = 0
C. x + y = 0
D. x – y = 0
Answer» D. x – y = 0
Discussion
17.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax + by and v = ax – by. For what condition will the flow field be continuous?

A. impossible
B. possible if a = b
C. possible if a = 2b
D. possible for all values of a and b
Answer» E.
Discussion
18.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = bxy + ay2. The condition for the flow field to be continuous is

A. independent of the constants (a; b) but dependent on the variables (x; y)b) independent of the variables (x; y) but dependent on the constants (a; b)c) independent of both the constants (a; b) and the variables (x; y)d) dependent on both the constants (a;
B. but dependent on the variables (x; y)b) independent of the variables (x; y) but dependent on the constants (a; b)
C. independent of both the constants (a; b) and the variables (x; y)
D. dependent on both the constants (a; b) and the variables (x; y)
Answer» B. but dependent on the variables (x; y)b) independent of the variables (x; y) but dependent on the constants (a; b)
Discussion
19.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = cxy +dy2. What should be the condition for the flow field to be continuous?

A. (a + b)x + (c + d)y = 0b) (a + c)x + (b + d)y = 0c) (2a +
B. x + (c + d)y = 0b) (a + c)x + (b + d)y = 0c) (2a + b)x + (c + 2d)y = 0d) (2a +
C. x + (b + d)y = 0c) (2a + b)x + (c + 2d)y = 0d) (2a + c)x + (b + 2
D. y = 0b) (a + c)x + (b + d)y = 0c) (2a + b)x + (c + 2d)y = 0d) (2a + c)x + (b + 2d)y = 0
Answer» E.
Discussion
20.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = axy and v = bx2 + cy2. What should be the condition for the flow field to be continuous?

A. a + b = 0
B. a + c = 0
C. a + 2b = 0
D. a + 2c = 0
Answer» E.
Discussion
21.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy + cy2 and v = cxy. What should be the condition for the flow field to be continuous?

A. a + c = 0
B. b + c = 0
C. 2a + c = 0
D. 2b + c = 0
Answer» D. 2b + c = 0
Discussion
22.

In a two dimensional flow, the component of the velocity along the X-axis is u = ax2 + bxy + cy2.If v = 0 at y = 0, what will be the velocity component in the Y-direction?

A. v = 2axy + by2
B. v = 2axy + b ⁄ 2 y2
C. v = -2axy – b ⁄ 2 y2
D. v = -axy – b ⁄ 2 y2
Answer» D. v = -axy – b ⁄ 2 y2
Discussion
23.

Two pipes, each of diameter d, converge to form a pipe of diameter D. What should be therelation between d and D such that theow velocity in the third pipe becomes half of that in eachof the two pipes?

A. D = d/2
B. D = d/3
C. D = d/4
D. D = d/5
Answer» B. D = d/3
Discussion
24.

If a liquid enters a pipe of diameter d with a velocity v, what will it’s velocity at the exit if the diameter reduces to 0.5d?

A. v
B. 0.5v
C. 2v
D. 4v
Answer» E.
Discussion
25.

IF_THE_SYSTEM_IS_IN_STEADY_STATE,_IT_IS_IN_AN_EQUILIBRIUM_STATE.?$

A. True
B. False
Answer» C.
Discussion
26.

WHICH_OF_THE_FOLLOWING_REPRESENTS_THE_BEST_DEFINITION_FOR_THE_DIFFUSION_LENGTH_FOR_HOLES??$

A. Average distance which an electron is injected travels before recombining with an electron
B. Average distance which a hole is injected travels before recombining with an electron
C. Average distance which a hole is injected travels before recombining with a hole
D. Average distance which an electron is injected before recombining with a hole
Answer» C. Average distance which a hole is injected travels before recombining with a hole
Discussion
27.

IN_A_TWO_DIMENSIONAL_FLOW,_THE_COMPONENT_OF_THE_VELOCITY_ALONG_THE_X-AXIS_AND_THE_Y-AXIS_ARE_U_=_AXY_AND_V_=_BX2_+_CY2._WHAT_SHOULD_BE_THE_CONDITION_FOR_THE_FLOW_FIELD_TO_BE_CONTINUOUS??$

A. a + b = 0
B. a + c = 0
C. a + 2b = 0
D. a + 2c = 0
Answer» E.
Discussion
28.

CALCULATE_THE_POTENTIAL_WHEN_A_CONDUCTOR_OF_LENGTH_2M_IS_HAVING_AN_ELECTRIC_FIELD_OF_12.3UNITS.?$

A. 26.4
B. 42.6
C. 64.2
D. 24.6
Answer» E.
Discussion
29.

MASS_CAN_NEITHER_BE_CREATED_NOR_BE_DESTROYED_IS_THE_PRINCIPLE_OF_______?$

A. Energy equation
B. Momentum equation
C. Continuity equation
D. Bernoulli’s principle
Answer» D. Bernoulli‚Äö√Ñ√∂‚àö√ë‚àö¬•s principle
Discussion
30.

WHAT_IS_THE_DIFFUSION_LENGTH_FOR_ELECTRONS_WHEN_DN=10CM2/S_AND_‚ÂÀ√¨‚ÀÖ√´N=40S??$#

A. 50cm
B. 25cm
C. 20cm
D. 15cm
Answer» D. 15cm
Discussion
31.

In_a_two_dimensional_flow,_the_component_of_the_velocity_along_the_X-axis_and_the_Y-axis_are_u_=_ax2_+_bxy_and_v_=_cxy_+dy2._What_should_be_the_condition_for_the_flow_field_to_be_continuous?$

A. (a + b)x + (c + d)y = 0
B. (a + c)x + (b + d)y = 0
C. (2a + b)x + (c + 2d)y = 0
D. (2a + c)x + (b + 2d)y = 0
Answer» E.
Discussion
32.

On_equating_the_generic_form_of_current_density_equation_and_the_point_form_of_Ohm’s_law,_we_can_obtain_V=IR._State_True/False.$#

A. True
B. False
Answer» B. False
Discussion
33.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = bxy + ay2. The condition for the flow field to be continuous is

A. independent of a and b
B. independent of a and c
C. independent of b and c
D. independent of a, b and c
Answer» E.
Discussion
34.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ay2 + bxy and v = ax2 + bxy. The flow will be continuous if

A. a + b = 0
B. a – b = 0
C. x + y = 0
D. x – y = 0
Answer» D. x ‚Äö√Ñ√∂‚àö√ë‚àö¬® y = 0
Discussion
35.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax + by and v = ax – by. For what condition will the flow field be continuous?$

A. impossible
B. possible if a = b
C. possible if a = 2b
D. possible for all values of a and b
Answer» E.
Discussion
36.

In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy + cy2 and v = cxy. What should be the condition for the flow field to be continuous?

A. a + c = 0
B. b + c = 0
C. 2a + c = 0
D. 2b + c = 0
Answer» D. 2b + c = 0
Discussion
37.

Find the resistance of a cylinder of area 200 units and length 100m with conductivity of 12 units?

A. 1/24
B. 1/48
C. 1/12
D. 1/96
Answer» B. 1/48
Discussion
38.

When Reynold’s number limits to infinity, inviscid flow is approached?#

A. True
B. False
Answer» B. False
Discussion
39.

Which of the following represents the continuity equation?

A. dp/dt=-(p-p0)/τp+Dp(d<sup>2p</sup>/dx<sup>2</sup>)-µpd(ρϵ)/dx
B. dp/dt=-(p-p0)/τp-Dp(d<sup>2p</sup>/dx<sup>2</sup>)-µpd(ρϵ)/dx
C. dp/dt=-(p-p0)/τp+Dp(d<sup>2p</sup>/dx<sup>2</sup>)+µpd(ρϵ)/dx
D. dp/dt=(p-p0)/τp-Dp(d<sup>2p</sup>/dx<sup>2</sup>)-µpd(ρϵ)/dx
Answer» B. dp/dt=-(p-p0)/‚âà√¨‚àö√´p-Dp(d<sup>2p</sup>/dx<sup>2</sup>)-¬¨¬®¬¨¬µpd(‚âà√¨‚àö√ñ‚âà√¨¬¨¬µ)/dx
Discussion
40.

In a two dimensional flow, the component of the velocity along the X-axis is u = ax2 + bxy + cy2.

A.
B. v = 2axy + by<sup>2</sup>
C. v = 2axy + b ‚ÅÑ 2 y<sup>2</sup>
Answer» D.
Discussion
41.

Find the mobility of the electrons when the drift velocity is 23 units and the electric field is 11 units.

A. 1.1
B. 2.2
C. 3.2
D. 0.9
Answer» C. 3.2
Discussion
42.

The equation which results in the change in pressure with change in the vertical height is called as __________

A. energy equation
B. momentum equation
C. continuity equation
D. hydrostatic equation
Answer» E.
Discussion
43.

What is the diffusion length for holes when Dp=25cm2/s and τp=25s?$

A. 25cm
B. 1cm
C. 0.04cm
D. 50cm
Answer» B. 1cm
Discussion
44.

Calculate the electric field when the conductivity is 20 units, electron density is 2.4 units and the velocity is 10m/s. Assume the conduction and convection current densities are same.

A. 2.4
B. 4.8
C. 3.6
D. 1.2
Answer» E.
Discussion
45.

The differential form of continuity equation is __________

A. ‚àá.u=constant
B. Dv/Dt=0
C. ρ/t + ∇.(ρV)=0
D. ρ=0
Answer» D. ‚âà√¨‚àö√ñ=0
Discussion
46.

What of the following conditions satisfies when the number of holes which are thermally generated is equal to the holes lost by recombination?

A. I≠0
B. dp/dt≠0
C. g=p/τ
D. g≠p/τ
Answer» D. g‚Äö√Ñ√∂‚àö¬¢‚Äö√тĆp/‚âà√¨‚àö√´
Discussion
47.

Two pipes, each of diameter d, converge to form a pipe of diameter D. What should be the relation between d and D such that the flow velocity in the third pipe becomes double of that in each of the two pipes?

A. D = d
B. D = 2d
C. D = 3d
D. D = 4d
Answer» B. D = 2d
Discussion
48.

Find the electron density when convection current density is 120 units and the velocity is 5m/s.

A. 12
B. 600
C. 24
D. 720
Answer» D. 720
Discussion
49.

Which of the flowing is an example of incompressible flow?

A. gas
B. sponge
C. water
D. gel
Answer» D. gel
Discussion
50.

The change in the carrier density is due to

A. Flow of incoming flux
B. Flow of outgoing flux
C. Difference of flow between incoming and outgoing flux
D. Difference of flow between incoming and outgoing flux plus generation and minus recombination
Answer» E.
Discussion