Explore topic-wise InterviewSolutions in Current Affairs.

A particle is executing simple harmonic motion along the x-axis with amplitude $4cm$ and time period $1.2s$. The minimum time taken by the particle to move from $x=+2cm$ to $x=+4cm$ and back again is

The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows:

A particle, which is constrained to move along the $x-$ axis, is subjected to a force from the origin as $F\left(x\right)=-kx+a{x}^3$. Here $k$ and $a$ are positive constants. For $x=0$, the functional form of the potential energy $U\left(x\right)$ of particle is

The figure shows a simple potentiometer circuit for measuring a small $\text{EMF}$ produced by a thermocouple.





The metre wire $PQ$ has a resistance of $5\Omega$ and the driver cell has an $\text{EMF}$ of $2.00\text{V}$. If a balance point is obtained $0.6\text{m}$ along $PQ$, when measuring an $\text{EMF}$ of $6.00\text{mV}$, what is the value of resistance $R$?

Three identical carrom coins, each of radius $5\text{cm}$ are placed touching each other on a horizontal surface such that an equilateral triangle is formed when the centres of the coins are joined. Find the coordinates of this centre of mass, if the origin is fixed at the centre of coin A, as shown in figure.

The stopping potential in a photoelectric experiment is linearly related to the inverse of the wavelength $\frac{1}{\lambda }$ of the light falling on the cathode. The potential difference applied across an X-ray tube is linearly related to the inverse of the cutoff wavelength $\frac{1}{\lambda }$ of the X-ray emitted. Show that the slopes of the lines in the two cases are equal and find its value.

My Teacher said me that surface of moon also deals with some pressure but how is this possible even if there is no air on the moon

Identify the object used in the given images for bending the light in a different direction.

Two discs have moments of inertia $I_{1}and{I}_2$ about their respective axes perpendicular to the plane and passing through the center. They are rotating with angular speeds, ${\omega }_{1}and{\omega }_2$ respectively and are brought into contact face to face with their axes of rotation coaxial. The loss in kinetic energy of the system in the process is given by :

Figure shows two equipotential lines in $XY$ plane for an electric field. The $X$-component of the electric filed, $E_x$ and $Y$-component, $E_y$ in the space between these equipotential lines are respectively

Figures
10.23 (a) and (b) refer to the steady flow of a (non-viscous) liquid.
Which of the two figures is incorrect? Why?

In the circuit shown below, the switch is connected to position $1$ for a very long time. What is the maximum current flowing through the circuit, when the switch is taken to position $2$?

1. 0

A ball moving at a speed of $3\text{m/s}$ approaches a wall moving towards it with a speed of $3\text{m/s}$. After the perfectly elastic collision, the speed of the ball will be

An object is thrown along a direction inclined at an angle of ${45}^{\circ }$ with the horizontal direction. The horizontal range of the particle is equal to

The hydration energy of Mg²⁺ ions is larger than that of

A plane mirror is placed on an incline with inclination $20°$. An incident ray gets reflected as shown below. What is the angle of reflection?

A cylindrical capacitor of inner radii $R$ and outer radii $2R$ is filled with two dielectrics of constant $K_1$ and $K_2$ respectively. Each dielectric occupies half the length of the cylinder. Find the capacitance of the system between the inner and outer cylinders.

[IIT 1982; RPET 1995, 2000; DCE 2000; UPSEAT 2001]

Two blocks of masses $m_1=2$ kg and $m_2=4$ kg hang over a massless pulley as shown in figure. A force F0 = 100N acting at the axis of the pulley accelerates the system upward. Then

A gas mixture consists of $2$ moles of oxygen and $4$ moles of argon at temperature $T$. Neglecting all vibrational modes, the total internal energy of the system is

Derive an expression for wheatstWhe bridge

What are conditions for rolling of the tyre of the car (about friction and velocity point of view)?

A ball is thrown upward with an initial velocity $V_0$ from the surface of the earth. The motion of the ball is affected by a drag force equal to $m\gamma v^2$ (where $m$ is mass of the ball, $v$ is its instantaneous velocity and $\gamma$ is a constant). Time is taken by the ball to rise to its zenith is:

A horizontal force of $10\text{N}$ is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is $0.2$. The weight of the block is

A rubber cube of side $5\text{cm}$ has one side fixed while a tangential force equal to $1800\text{N}$ is applied to the opposite face. Find the shearing strain and the lateral displacement of the strained face. Modulus of rigidity for rubber is $2.4\times {10}^6{\text{N/m}}^2$.

A spherical shell of radius 10 cm is carrying a charge q. if the electric potential at distances 5 cm, 10 cm and 15 cm from the centre of the spherical shell is $V_1,V_{2}and{V}_3$ respectively, then

Q1. An isotone of 76Ge32 is

a) 77Ge32

c) 77Se34

b) 77As33

d) 79Se34

Q2. Thomson’s model was successful in explaining

a) The H atomic spectrum

c) The electrical neutrality of atom

b) The circular motion of electrons

d) Wave nature of electrons

Q3. The number of electrons carrying a total charge of 1 C is –

a) 6.023 X 1023

c) 6.25 X 1018

b) 6.25 X 1020

d) 6.023 X 1022

Q4. With an initial velocity V, an α particle can approach up to a distance r from a certain nucleus. If a proton is used instead of α particle to bombard the same nucleus, calculate the distance of closest approach with the same initial velocity. [Hint: take relative mass and charge !! ]

a) r

c) r/2

b) 2r

d) r2

Q5. Which of the following atoms is expected to be most paramagnetic?

a) 3Li

c) 5B

b) 4Be

d) 6C

Q6. The work function WA for a photoelectric metal A is 2 eV and WB for another metal B is 4 eV. If the photons of energy EA strike the surface of A, the ejected photoelectrons have a minimum De-Broglie wavelength λA and if photons of energy EB strike surface B, the DeBroglie wavelength of the ejected electrons is λB. If EB = EA + 0.5 in eV and if λB = 2λA, calculate the value of the stopping potential for metal A.

a) 2 V

c) 3 V

b) 4 V

d) 0.5 V

Q7. The radial wave-function for an orbital is R = (1/45.96) X ρ 2 X Z3/2 X e-ρ/2 , where ρ = 2Zr/3. If the orbital angular momentum for an electron situated in this orbital is √6. (h/2π), identify the correct orbital. [Clue: number of radial nodes!!]

a) 4p

c) 4d

b) 3d

d) 3s

Q8. Heisenberg’s uncertainty principle is applicable for

a) a moving car

c) a flying bird

b) moving electrons

d) all of these

Q9. Kinetic energy and potential energy of electron in H atom at the 2nd excited state is a) 3.4 eV, - 6.8 eV

c) 13.6 eV, -27.2 eV

b) 10.2 eV, -20.4 eV

d) 1.51 eV, -3.02 eV

Q10. The work-function of a metal is 4 eV. The longest wavelength of light that can cause photoelectric emission from this metal is

a) 400 nm

c) 310 nm

b) 124 nm

d) 230 nm

Q11. Which of the following sets of quantum numbers is wrong?

a) n = 2, l = 2, m = 2, s = +1/2

c) n = 2, l = 0, m = 0, s = -1/2

b) n = 2, l = 1, m = 1, s = +1/2

d) n = 2, l = 0, m = 0, s = +1/2

Q12. Maximum number of electrons in a subshell with azimuthal quantum number l is

a) 4l + 2

c) 2l + 1

b) 2l 2

d) l.(l+1)

Q13. What is the longest wavelength line in the Lyman series of He+ ion?

a) 3R

c) 1/3R

b) 1/4R

d) ∞

Q14. The number of maxima in radial distribution curve of 5d orbital is

a) 0

c) 1

b) 2

d) 3

Q15. In which of the following orbits of hydrogen atom, is the speed of electron maximum?

a) n = 2

c) n = 4

b) n = 3

d) n = 1

Q16. The sub-shell that arises after f is called g. For an electron in any g orbital, which of the following is not the correct set of quantum numbers?

a) n = 5, l = 4, m = -3, s = +1/2

c) n = 5, l = 3, m = -1, s = +1/2

b) n = 5, l = 4, m = +2, s = +1/2

d) n = 5, l = 4, m = +4, s = +1/2

Q17. For which system, is the Bohr model not applicable?

a) C 5+

c) B4+

b) N 6+

d) Be2+

Q18. Total number of lines in Lyman series of hydrogen will be ( n = number of orbits present in atom)

a) n

c) n -1

b) n -2

d) {n (n + 1)}/2

Q19. Number of visible lines when an electron returns from 5th orbit to ground state for hydrogena)

a)5

c) 4

b) 3

d) 10

Q20. The ratio of the energy of a photon of 200 nm wavelength radiation to that of 400 nm radiation is

a) 1/4

c) 2

b) 1/2

d) 4

Q21. XY plane is nodal plane of which orbital?

a) dxy

c) py

b) px

d) pz

Q22. The total electronic spin resulting from d7 configuration is –

a) 1

c) 3/2

b) 5/2

d) 2

Q23. The mass of cathode ray is

a) Same for different gases

c) minimum for hydrogen

b) Different for different gases

d) maximum for hydrogen

Q24. Which is not a property of a photon?

a) Momentum

c) energy

b) Angular momentum

d) wave-number

Q25. A molecule absorbs a photon of wavelength λ and re-emits the same energy into two photons of wavelength λ1 and λ2 respectively. Find the correct relation

a) λ = (λ1 + λ2)/ λ1. λ2

c) λ = λ1. λ2/ (λ1 + λ2)

b) λ = (λ1 + λ2)2 / λ1. λ2

d) λ = λ1. λ2/ (λ1 + λ2)2

Q26. The De-Broglie wavelength (in Å) of an electron in 2nd orbit in hydrogen

a) λ = 1.058π

c) λ = 1.587π

b) λ = 2.116π

d) λ = π

Q27. An oil drop has -6.4 X 10-19 C charge. Find the number of electrons in this oil drop. a) 2

c) 6

b) 4

d) 8

Q28. The approximate size of the nucleus 64Ni is

a) 3 fm

c) 5 fm

b) 4 fm

d) 2 fm

Q29. The ratio of area enclosed by 2nd orbit of Be3+ and that by 1st orbit of He+ is

a) 1:4

c) 1:8

b) 4:1

d) 8:1

Q30. Solving Schrödinger equation does not give information about the quantum number a) l

c) s

b) n

d) m

Two charged particles kept at equipotential plane have same potential,does this mean they have zero potential?

In a Young's double slit experiment

$\lambda =500nm,d=1mm\mathrm{and}D=1m.$

The minimum distance from the central maximum for which the intensity is half of the maximum intensity is