Explore topic-wise InterviewSolutions in Current Affairs.

This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.

1.

A long rectangular slab of transparent medium of thickness 'd' placed on a table with its length parallel to the x-axis and width parallel to the y-axis. A ray of light travelling in air makes a near normal incidence on the slab as shown. Taking the point of incidence as origin (0,0,0). The refraction index mu of the medium varies as mu = (mu_0)/(1 - (x/r)),where mu_1 andr( > d) are constants. The refractive index of air is m_0The refractive index mu_A of the medium at A

Answer»

`(mu_0)/(SQRT(1-(d/r)^2))`
`(mu_0)/(sqrt(1-(d/r)^2))`
`(-mu_0)/(sqrt(1+(r/d)^2))`
`(mu_0)/(sqrt(1+(d/r)^2))`

ANSWER :B
Discussion
2.

A long rectangular slab of transparent medium of thickness 'd' placed on a table with its length parallel to the x-axis and width parallel to the y-axis. A ray of light travelling in air makes a near normal incidence on the slab as shown. Taking the point of incidence as origin (0,0,0). The refraction index mu of the medium varies as mu = (mu_0)/(1 - (x/r)),where mu_1 andr( > d) are constants. The refractive index of air is m_0The x-coordinate of the point A where the ray intersects the upper surface of the slab air boundary is

Answer»

`R { 1 - SQRT(1-(d/r)^2 )}`
`r { + sqrt(1-(d/r)^2) }`
`r{1-sqrt(1+(d/r)^2) }`
`r{1+sqrt(1+(d/r)^2) }`

ANSWER :A
Discussion
3.

एक घन के अंदर rhoपरिमाण के आवेश वाले 8 द्विध्रुव रखे हैं। घन से निर्गत कुल विद्युत फ्लक्स का मान होगा-

Answer»

`(8rho)/epsilon_0`
`(16rho)/epsilon_0`
`rho/epsilon_0`
शून्य

ANSWER :D
Discussion
4.

Possessing energy E of photon's wavelength in air is…..

Answer»

`(hc)/(E )`
`(h)/(cE)`
`(c )/(hE)`
`hxxcE`

SOLUTION :WAVELENGTH in air ,
`lambda=(c )/(V)`
`THEREFORE lambda=(hc)/(hv)`
`therefore lambda=(hc)/(E )`
Discussion
5.

While light falls on one face of crown glass prism of refracting angle 50^(@). The angle of incidence is 30^(@). Find the (a) mean deviation produced by the prism and (b) the angle of dispersion (mu_(v)=1.538,mu_(R)=1.52).

Answer»


ANSWER :`(a) 31^(@)45'` ; `(B) 1^(@)18'`
Discussion
6.

The effective capacitence inmuFin between A and B will be

Answer»

`28//9`
4
5
18

Answer :C
Discussion
7.

A magnet makes 10 oscillations per minute at a place where the angle of dip is 45^(@) and the resultant earth's field is 0.4 gauss. Calculate the number of oscillations made per second by the same magnet at another place where the angle of dip is 60^(@) and the resultant earth's field is 0.5 gauss.

Answer»

SOLUTION :`0.157 s^(-1)`
Discussion
8.

In the question number 11, the peak voltage of the source is

Answer»

305 V
310 V
311 V
315 V

Solution :`V_(m)=sqrt(2)V_("RMS")=220 sqrt(2) V~~ 311 V`.
Discussion
9.

If the kinetic energy of pulse travelling in a taut string is Kxx10^(-2) mJ then find the value of K (Given T=10 N & mu=0.1 kg//m

Answer»


Solution :at given time `y=m_(1)X 0 LT x lt 0.1` m
`=m_(2)x+C 0.1 m lt x lt 0.15` m
`m_(1)=10^(-3)/0.1 = 10^(-2) (V_(omega)=sqrt(T/mu))`
`m_(2)=10^(-3)/0.05=2xx10^(-2)`
`dK=1/2dmV_(p)^(2)=1/2mu dx(-V_(omega)(dely)/(delx))^(2)`
`intdK=1/2muV_(omega)^(2)[m_(1)^(2) underset0overset(0.1)intdx+m_(2)^(2) underset(0.1)overset(0.15)intdx]`
`K=1/2T[m_(1)^(2)(0.1)+m_(2)^(2)(0.5)]`
`K=1/2T[10^(-4)(0.1)+4xx10^(-4)(0.5)]`
`=10/2[10^(-4)](0.3)=0.15mJ`
Discussion
10.

The coordinates of a particle moving in a plane are given by x(t)=acos(pt)andy(t)=bsin(pt)" where "a,b(lta)andp are positive constants of appropriate dimensions. Then

Answer»

the PATH of the particle is an ellipse.
the velocity and acceleration of the particle are normal to each other at `t=pi//(2P)`.
the acceleration of the particle is always directed toward a focus.
the distance traveled by the particle in time interval t = 0 to `t=pi//(2p)` is a.

Answer :A::C
Discussion
11.

Wavelength of light of frequency 100Hz.

Answer»

`4xx10^6`m
`3xx10^6` m
`2xx10^6`m
`5xx10^-5`m

Answer :C
Discussion
12.

Asource of sound vibrates according to the equation y=0.03sinpit. The velocity of the wave is 1.5m/s. What is the wavelength of the wave ?

Answer»

6m
3m
1.5m
4.5m

Answer :B
Discussion
13.

The interior of a conductor can have no excess charge in the static situation'. Explain

Answer»

Solution :A neutral CONDUCTOR has equal AMOUNTS of positive and negative CHARGES in every small volume or surface element.
When the conductor is charged the excess charge can reside only on the surface in the stadc situation.
Let US consider a Gaussian surface inside the conductor and close to the surface.
At all points inside the conductor `vecE` =0 hence from `phi_(E)=ointvecE.dvecS,phi_(E)=0`
According to Gauss.s law
v
Hence, there is no net charge at any point inside the conductor and any excess charge must reside at the surface.
Discussion
14.

Match list A and list B accurately{:("List - A ","List - B"),("a)spherical wave front","e)linear source"),("b)plane wave front","f)point light source "),("c) cylindrical wave front","g) at infinite distance"):}

Answer»

(a,f), (B,g), (C,e)
(a,f), (b,e), (c,g)
(a, g), (b,f), (c,e)
(a,e), (b,g), (c,f)

ANSWER :A
Discussion
15.

An equiconvex lens of focal length 20 cm is cut into two equal halves perpendicular to the principalaxis and kept at a separation of 10 cm co-axially. What is the focal length of the system?

Answer»

35cm
20cm
22.9cm
15cm

Answer :C
Discussion
16.

Express 16 mg mass into equivalent energy in eV.

Answer»

Solution :Here `m = 16 mg = 16 XX 10^(-6) KG, C = 3 xx 10^(8) ms^(-1)`
Equivalent energy, E = `me^(2)`
` = 16 xx 10^(-6) xx (3 xx 10^(8))^(2)`J
`= (16 xx 10^(-6) xx(3 xx10^(8))^(2))/(1.6 xx 10^(-19)) EV`
`E = 9 xx 10^(30) eV`
Discussion
17.

The motion of copper plate is damped when it is allowed to oscillate between the two poles of a magnet what is the cause of this damping ?

Answer»

Solution :i. As the plate oscillate, the changing MAGNETIC flux through the plate produces a strong eddy current in the DIRECTION, which opposes the cause.
ii. Also copper being diamagnetic SUBSTANCE, it gets magnetised in the OPPSITE direction, so the motion of copper plate is stopped.
Discussion
18.

In a transistor the emitter current is 1.01 times as large as the collector current .If the emitter current is 12.12 mA. Find the base current.

Answer»

SOLUTION :`I_(B)=I_(E)-I_(C)`=12.12-12=0.12 mA
Discussion
19.

The highest frequency of radiowaves which when sent at some angle towards the ionosphere , gets reflected from that and returns to the earth is called

Answer»

CRITICAL FREQUENCY
maximum UNUSABLE
polarisation of waves
NONE of the above

ANSWER :B
Discussion
20.

Name the type of diode whose -V characteristics are shown in What does the points P and Q in graph repre sent ?

Answer»

<P>

SOLUTION :The junction diode a solar cell. Here point P indicates "open circuit voltage" `(V_(OC))` and point Q indicates "short circuit CURRENT" `(l_(SC))`.
Discussion
21.

A system consists of two concentric spherical shells of radii a and b (b>a) maintained at tempareture T_1 and T_2 respectively.The radial rate of flow of heat through subtance between the two concentric spherical shells is proportional to

Answer»

B - a
`(AB)/(b - a)`
`log_e(b/a)`
`(b - a)/(ab)`

ANSWER :B
Discussion
22.

What is meant by wattles current ?

Answer»

Solution :The COMPONENT of current `(I_(RMS)sinphi)`, which has a PHASE ANGLE of `(pi)/(2)` with the voltage is called REACTIVE component. The power consumed is zero. So that it is also known as .WATTLESS. current.
Discussion
23.

The tangent law is applied in .............

Answer»


ANSWER :TANGENT galvenometer
Discussion
24.

Kirchoff'slaw i.e., sum i=0, at a junction, deals with the conservation of

Answer»

CHARGE
ENERGY
MOMENTUM
ANGULAR momentum

ANSWER :A
Discussion
25.

Two balls are thrown simultaneously in air. The acceleration of the centre of mass of the two balls when in air,

Answer»

depends on the masses of the two balls
depends on the speeds of the two balls
is equal to g (Acceleration DUE to GRAVITY)
depends on the direction of motion of the two balls.

Solution :We know that,
Acceleration of centre of MASS
`a_(CM)=(m_(1)a_(1)+m_(2)a_(2))/(m_(1)+m_(2))`
`a_(cm)=(g(m_(1)+m_(2)))/(m_(1)+m_(2))`
`a_(cm)=g`
Discussion
26.

A uniform solid cone (height h=4m, alpha=30^(@)) is inclined agains a vertical axis as shown in the figure. The cone rotates about its own axis as well as rotates about the vertical axis with angular speeds marked in the diagram. If the cone does not slip at point B,find (omega_(1))/(omega_(2))

Answer»


Solution :`omega_(1) h tan alpha= omega_(2)R`
`IMPLIES(omega_(1))/(omega_(2))=(R//h)/(tanalpha)=1`
Discussion
27.

The electric field on two sides of a large charged plate is shown in the below Fig. The charge density on the plate in S.I. units is given by (epsilon_0is the permittivity of free in S.I. units)

Answer»

`2 epsilon_0`
`4 epsilon_0`
`10 epsilon_0`
zero

Answer :B
Discussion
28.

A rectangul ar coil of wire of 100 turns and 10xx15cm^(2) size carrying a current of 2Amp. is in a magnetic field of induction 2 xx 10^(-3)wb//m^(2). If the normal drawn to the plane of the coil makes an angle 30° with the field, then the torque on the coil is

Answer»

`3XX10^(-5)N-m`
`3xx10^(_3)N-m`
`3sqrt3xx10^(-5)N-m`
`3sqrt3xx10^(-3)N-m`

ANSWER :B
Discussion
29.

Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.2.7 K [temperature associated with the isotropic radiation filling all space - thought to be a relic of the 'big - bang' origin of the universe].

Answer»

Solution :Acording to Wien.s LAW,
`lambda_(m)T=0.0029 mK`,
`therefore lambda_(m)=(0.29cm K)/(2.7 K)=0.11 CM`
We GET, `lambda_(m)~~ 11xx10^(-4)m`
Radiation with above WAVELENGTH in the section of ..Microwaves.. of electromagnetic spectrum.
Discussion
30.

The following situation regards the physical pendulum. Column-1 gives the different types of bodies. Column -2 gives the different axes about which they can possibly perform SHM. Column-3 gives possible time periods. (The plane of the four figure is the vertical plane) Pick the option for minimum value of V_(A)

Answer»

(I) (ii) (P)
(II) (i) (R )
(III (IV) (Q)
(II) (iii) (S)

Answer :C
Discussion
31.

The following situation regards the physical pendulum. Column-1 gives the different types of bodies. Column -2 gives the different axes about which they can possibly perform SHM. Column-3 gives possible time periods. (The plane of the four figure is the vertical plane) Pick correct option

Answer»

(I) (II) (S)
(II) (ii) (P)
(I) (ii) (R )
(IV) (i) (Q)

ANSWER :B
Discussion
32.

Assertion A ray of light travels from first medium to second medium. In first medium, angle of ray with normal is i_(1) =30^(@) and in second medium i_(2) = 60^(@) Then, second medium is rarer medium.

Answer»

If both Assertion and REASON are true and Reason is the correct explanation of Assertion.
If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
If Assertion is true but Reason is false.
If Assertion is false but Reason is true.

Solution :(C) In RARER medium, ray of LIGHT MOVES away from the normal. Further,
`mu_(1)sin30^(@)=mu_(2)sin60^(@)`
`therefore(mu_(1))/(mu_(2))=""_(2)mu_(1)=(sin60^(@))/(sin30^(@))`
Discussion
33.

Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.5890 Å - 5896 Å [double lines of sodium]

Answer»

SOLUTION :It corresponds to YELLOW colour in visible PART of electromagnetic SPECTRUM.
Discussion
34.

What happens to the pressure of a sample of helium gas if the temperature is increased from 200 K to 800 K, with no change in volume?

Answer»

Solution :The IDEAL GAS law, PV=nRT, tells US that if V remains constant, then P is PROPORTIONAL to T. so, if T increases by a factor of 4, then so will P.
Discussion
35.

An electron moving in a uniform magnetic field of B has its radius directly proportional to

Answer»

its charge
magnetic field
SPEED
NONE of these

Solution :As per relation `r = (mv)/(qB)`, the radius of circular path of electron, when a magnetic field B is applied at right ANGLES to its motion, is directly proportional to its speed i.e., `r PROP V`
Discussion
36.

A toroid has a mean radius R equal to 20//pi cm, and a total of 400 turns of wire carrying a current of 2.0 A. An aluminium ring at temperature 280 K inside the toroid provides the core. If the magnetisation I is 4.8 xx 10^(-2) A m^(-1), then, choose the correct option(s).

Answer»

MAGNETIC intensity in the core is `1000 A m^(-1)`
Susceptibility of the aluminium at TEMPERATURE `280 K is 2.4 xx 10^(-5)`.
If the temperature of the aluminium ring is raised 10 320 K, then the magnetization will be `4.2 xx 10^(-2) Am^(-1)`.
Susceptibility of aluminium at temperature 320 K is `2.1 xx 10^(-5)`

Solution :The NUMBER of turns per uni" length of the toroid is
`n = (400)/(2piR)`
The magnetic intensity H in the core is
`H = ni = (400xx 2.0A)/(2pi20/rxx10^(-2)m)=2000Am^(-1)`
The susceptibility is
`X = I/H = (4.8xx10^(-2)Am^(-1))/(2000Am^(-1))=2.4xx10^(-5)`
The susceptibility X of a paramagncrie substance VARIES with absolute temperature as X = c/T,
`therefore X_(2)//X_(1) = T_(1)//T_(2)`
The susceptibility of aluminium at temperature 320 K is. therefore,
`X_(2) = (280)/(320) xx 2.4 xx 10^(-5) = 2.1 xx 10^(-5)`
Thus the magnetisation at 320 K is
`I = XH -= 2.1 xx 10^(-5) xx 2000 Am^(-1) = 4.2 xx 10^(-2) Am^(-1)`
Discussion
37.

Do free electrons travel to region of higher potential or lower potential ?

Answer»

Solution :No. There is NEGATIVE CHARGE on free ELECTRONS. The free electrons experience electrostatic FORCE in a direction opposite to the direction of ELECTRIC field. The direction of electric field is always from higher potential to lower. Hence, free electrons will move from lower potential to higher potential.
Discussion
38.

Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.21 cm (wavelength emitted by atomic hydrogen in interstellar space).

Answer»

Solution :GIVEN RADIATION of 21 CM wavelength is in the section of ..Radio waves.. of electromagnetic SPECTRUM towards higher FREQUENCY.
Discussion
39.

The drift velocity v_d of electrons varies with electric field strength E as

Answer»

`v_d` `ALPHA E`
`v_d` `ALPHA1/E`
`v_d` `alpha E^(1/2)`
`v_d``alpha1/(E^(1/2)`

ANSWER :A
Discussion
40.

A hexagon of side 'a' has a charge 'q' at each of its vertices. The electric field at the centre of hexagon is

Answer»

`0`
`(1)/(4pi in _0 ).(Q)/(a^(2))`
` (1)/(4pi in _0) . (6Q)/(a^(2))`
` (1)/(4pi in _0) .(6q^(2))/(a^(2))`

Answer :A
Discussion
41.

A photodiode as well as a LED are employed in forward bias arrangement.

Answer»

Solution :False-A photodiodeis invariably USED in REVERSE bias but a LED is used inforward bias ARRANGEMENT.
Discussion
42.

In the given network , the batteries getting charged are

Answer»

1 and 3
1,3, and 5
1 and 4
1,2, and 5

Solution :c. Applying Kirchhoff's law at A,C,D, the direction of the currents in each BRACH will be as shown in Fig. SA 2.1. Now, it is CLEAR from the figure that the batteries 1 and 4 are GETTING CHARGED.
Discussion
43.

Assertion: When the height of a TV transmission tower is increased by three times. The range covered is doubled. Reason: The range covered is proportional to the height of the TV transmission tower.

Answer»

A and R are TRUE and R is the correct explanation
Both A and R aer true but reason is not the correct explanation
a is true R is false
Both A and R are true

Answer :C
Discussion
44.

What is the value of acceleration due to gravity on the surface of the moon ? Given that the mass of the moon is 1//80 times that of the earth and diameter of the moon is 1//4 times that of earth (g=9.8m//s^2).

Answer»

`2.5xx10^3km//s`
`2.5xx10^2km//s`
`2.5xx10km//s`
`2:5km//s`

ANSWER :D
Discussion
45.

A pendulum clock is accurate on the Earth's surface. How slow will it be, if it is lifted to the hundredth floor of a sky-scraper? The height of a storey is 3 m.

Answer»


Solution :The period of oscillations of the pendulum at the surface of the Earth is `T_(0)=2pisqrt(l//g_(0))`. At an ALTITUDE h above the surface of the Earth it is `T=2pisqrt(l//g)`. We have `(DELTAT)/(T_(0))=(tau)/(tau_(0))`, where `tau_(0)=8.64xx10^(4)s` is the duration of a complete day and `tau` is the lag of the clock. HENCE
`tau=(tau_(0)DeltaT)/(T_(0))=((T)/(T_(0))-1)tau_(0)(SQRT(g_(0)//g-1))`
The acceleration due to gravity at the Earth.s surface is `g_(0)=(gammaM)/(R^(2))` while at an altitude h it is g `(gammaM)/((R+h)^(2))` where R is the radius of the Earth. After some simple transformations we obtain
`tau_(0)h//R`
Discussion
46.

Find the effective capacitance between the terminals m and n shown in figure.

Answer»

`3C`
`(7C)/(6 ) `
`(6C )/(7 )`
`5C `

Answer :B
Discussion
47.

A bomb is projected with speed 10 m/s at an angle 30^o with the horizontal. In the mid-air bomb explodes in different fragments and they all move in different directions. At the time when all fragments reach at ground, the displacement of the center of mass of bomb from initial point will be (g = 10 m/s^2)

Answer»

`5SQRT3` m
10 m
5 m
Zero

Answer :B
Discussion
48.

What are Delta L (as a multiple of the wavelength) and the phase difference in wavelengths) for the two rays if point Pis (a) a third side maximum and (b) a third minimum?

Answer»

SOLUTION :(a) `3lambda`, 3, (B) `2.5 LAMBDA`, 2.5
Discussion
49.

How does drift velocity of electrons in a metallic conductor vary with increase in temperature ? Give reason.

Answer»

Solution : On heating a conductor its resistance INCREASES and the CURRENT decreases. Consequently, the DRIFTVELOCITY of free ELECTRONS decreases.
Discussion
50.

A dipole is placed in a uniform electric field. Its potential energy will be minimum when the angle between the dipole moment and the electric field is

Answer»

`2PI`
`PI`
`pi/2`
zero

Answer :D
Discussion