JEE (Advanced) 2018 Paper-1
For each question, enter the correct numerical value (in decimal notation, truncated/rounded-off to the second decimal place; e.g. 6.25, 7.00, -0.33, -.30, 30.27, -127.30) using the mouse and the on-screen virtual numeric keypad in the place designated to enter the answer.
Three identical capacitors $$๐ถ_{1}, ๐ถ_{2}$$ and $$๐ถ_{3}$$ have a capacitance of 1.0 $$\mu$$๐น each and they are uncharged initially. They are connected in a circuit as shown in the figure and $$๐ถ_{1}$$ is then filled completely with a dielectric material of relative permittivity $$\epsilon_{r}$$.The cell electromotive force (emf) $$๐_{0}$$ = 8 ๐. First the switch $$๐_{1}$$ is closed while the switch $$๐_{2}$$ is kept open. When the capacitor $$๐ถ_{3}$$ is fully charged, $$๐_{1}$$ is opened and $$๐_{2}$$ is closed simultaneously. When all theย capacitors reach equilibrium, the charge on $$๐ถ_{3}$$ is found to be 5 $$\mu$$๐ถ. The value of $$\epsilon_{r}$$ =____________.
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In the xy-plane, the region y > 0 has a uniform magnetic field $$B_{1} \hat{k}$$ and the region y < 0 has another uniform magnetic field $$B_{2} \hat{k}$$. A positively charged particle is projected from the origin along the positive y-axis with speed $$v_{0} = \pi m s^{-1}$$ and t = 0 as shown in the figure.Neglect gravity in this problem. Let $$t = T$$ be the time when the particle crosses the x-axis from below for the first time. If $$B_2 = 4B_1$$, the average speed of the particle, in $$ m s^{-1}$$, along the x-axis in the time interval T is __________.
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Sunlight of intensity 1.3 $$kW ๐^{โ2}$$ is incident normally on a thin convex lens of focal length 20 ๐๐. Ignore the energy loss of light due to the lens and assume that the lens aperture size is much smaller than its focal length. The average intensity of light, in $$kW ๐^{โ2}$$, at a distance 22 ๐๐ from the lens on the other side is __________
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Two conducting cylinders of equal length but different radii are connected in series between two heat baths kept at temperatures $$๐_{1} = 300 ๐พ and ๐_{2}$$ = 100 ๐พ, as shown in the figure. The radius of the bigger cylinder is twice that of the smaller one and the thermal conductivities of the materials of the smaller and the larger cylinders are $$๐พ_{1} and ๐พ_{2}$$ respectively. If the temperature at the junction of the two cylinders in the steady state is 200 ๐พ, then $$\frac{๐พ_{1}}{๐พ_{2}}$$ =__________.
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In electromagnetic theory, the electric and magnetic phenomena are related to each other. Therefore, the dimensions of electric and magnetic quantities must also be related to each other. In the questions below, [E] and [B] stand for dimensions of electric and magnetic fields respectively, while $$[\epsilon_{0}]$$ and $$[\mu_{0}]$$ stand for dimensions of the permittivity and permeability of free space respectively. [L] and [T] are dimensions of length and time respectively. All the quantities are given in SI units.
If the measurement errors in all the independent quantities are known, then it is possible to determine the error in any dependent quantity. This is done by the use of series expansion and truncating the expansion at the first power of the error. For example, consider the relation $$Z = \frac{x}{y}$$. If the errors in x, y and z are $$\triangle x, \triangle y$$ and $$\triangle z$$ respectively, then $$Z \pm \triangle Z = \frac{x \pm \triangle x}{y \pm \triangle y}=\frac{x}{y} \left(1 \pm \frac{\triangle x}{x} \right) \left(1 \pm \frac{\triangle y}{y} \right)^{-1}$$.ย The series expansion for $$\left(1 \pm \frac{\triangle y}{y}\right)^{-1}$$, to to first power in $$\frac{\triangle y}{y}$$, is $$1 \mp \left(\frac{\triangle y}{y}\right)$$ The relative errors in independent variables are always added. So the error in z will beย $$\triangle z = z(\frac{\triangle x}{x} + \frac{\triangle y}{y})$$. The above derivation makes the assumption that $$\frac{\triangle x}{x} \ll 1, \frac{\triangle y}{y} \ll 1$$.Therefore, the higher powers of these quantities are neglected.
Consider the ratio $$\gamma=\frac{(1-a)}{(1+a)}$$ to be determined by measuring a dimensionless quantity ๐. If the error in the measurement of ๐ is $$\triangle a(\frac{\triangle a}{a} \ll 1)$$,then what is the error $$\triangle ๐ $$ in determining r?
In an experiment the initial number of radioactive nuclei is 3000. It is found that $$1000 \pm 40$$ nuclei decayed in the first 1.0 s. For $$\mid x \mid \ll 1$$, $$\ln(1 + x)$$ = x up to first power in x. The error $$\triangle \lambda$$, in the determination of the decay constant $$\lambda$$, in $$s^{-1}$$, is , is
For the following questions answer them individually
The compound(s) which generate(s) N2 gas upon thermal decomposition below $$300^\circ$$ is (are)
The correct statement(s) regarding the binary transition metal carbonyl compounds is (are) (Atomic numbers: Fe = 26, Ni = 28)
