PHYSICS 8th JAN S1 2020 - JEE MCQ

Effective capacitance of parallel combination of two capacitors C1 and C2 is 10μF. When these capacitors
are individually connected to a voltage source of 1V, the energy stored in the capacitor C2 is 4 times that
of C1. If these capacitors are connected in series, their effective capacitance(in μF) will be:

A leak proof cylinder of length 1m, made of a metal which has very low coefficient of expansion is floating
vertically in water at 0ºC such that its height above the water surface is 20 cm. When the temperature of
water is increased to 4ºC, the height of the cylinder above the water surface becomes 21 cm. The density
of water at T = 4ºC, relative to the density at T = 0ºC is close to:

At time t = 0 magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the
closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5 s, then
induced EMF(in μV) in the loop is:

When photon of energy 4.0 eV strikes the surface of a metal A, the ejected photoelectrons have maximum
kinetic energy TA eV and de-Broglie wavelength λA. The maximum kinetic energy of photoelectrons
liberated from another metal B by photon of energy 4.50 eV is TB = (TA – 1.5) eV. If the de-Broglie
wavelength of these photoelectrons λB = 2λA, then the work function(in eV) of metal B is:

The coordinates of centre of mass of a uniform flag shaped lamina (thin flat plate) of mass 4 kg. (The
coordinates of the same are shown in figure) are

The critical angle(in degree) of a medium for a specific wavelength, if the medium has relative permittivity 3 and
relative permeability 3/4 for this wavelength, will be:

The length of a potentiometer wire is 120 cm and it carries a current of 60 mA. For a cell of emf 5V and
internal resistance of 20Ω, the null point on it is found to be at 1000 cm. The resistance(in Ω) of whole wire is:

Consider a uniform rod of mass M = 4m and length l pivoted about its centre. A mass m moving with
velocity v making angle θ=π/4 to the rod's long axis collides with one end of the rod and sticks to it. The
angular speed of the rod-mass system just after the collision is:

In finding the electric field using gauss law the formula E=Q/(ε•A) is applicable. In the formula ε• is
permittivity of free space, A is the area of Gaussian surface and qen is charge enclosed by the Gaussian
surface. This equation can be used in which of the following situation

The graph which depicts the results of Rutherford gold foil experiment with α-particles is:
α-particles is:
Y = Number of scattered α-particles detected
(Plots are schematic and not to scale)

The plot that depicts the behaviour of the mean free time τ(time between two successive collisions) for
the molecules of an ideal gas, as a function of temperature (T), qualitatively, is: (Graphs are schematic
and not drawn to scale)

Three charged particles A, B and C with charges –4q, 2q and –2q are present on the circumference of a
circle of radius d. The charged particles A, C and centre O of the circle formed an equilateral triangle as
shown in figure. Electric field at O along x-direction is:

Boolean relation at the output stage-Y for the following circuit is:

The dimension of stopping potential V₀ in photoelectric effect in units of Planck's constant 'h', speed of
light 'c' and Gravitational constant 'G' and ampere A is

A thermodynamic cycle xyzx is shown on a V-T diagram.The P-V diagram that best describes this cycle is: (Diagrams are schematic and not to scale

Consider two solid spheres of radii R1 = 1m, R2 = 2m and masses M1 and M2, respectively. The
gravitational field due to sphere (1) and (2) are shown. The value of M₁/M₂

A particle is moving along the x-axis with its coordinate with time t given by x(t) = 10 + 8t – 3t^2. Another
particle is moving along the y-axis with its coordinate as a function of time given by y(t) = 5 – 8^t3.
At t = 1s, the speed of the second particle as measured in the frame of the first particle is given as√ v .
Then v (in m/s) is

A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the
curved surface is 30 cm and the refractive index of the lens material is 1.5, then the focal length of the
lens (in cm) is

A one metre long (both ends open) organ pipe is kept in a gas that has double the density of air at STP.
Assuming the speed of sound in air at STP is 300 m/s, the frequency difference between the fundamental
and second harmonic of this pipe is _______Hz.

Four resistances of 15Ω, 12Ω, 4Ω and 10Ω respectively in cyclic order to form Wheatstone's network.
The resistance that is to be connected in parallel with the resistance of 10Ω to balance the network is
________Ω.