1
WB JEE 2020
+1
-0.25 When 100 g of boiling water at 100$$^\circ$$ C is added into a calorimeter containing 300 g of cold water at 10$$^\circ$$ C, temperature of the mixture becomes 20$$^\circ$$ C. Then, a metallic block of mass 1 kg at 10$$^\circ$$ C is dipped into the mixture in the calorimeter. After reaching thermal equilibrium, the final temperature becomes 19$$^\circ$$ C. What is the specific heat of the metal in CGS unit?
A
0.01
B
0.3
C
0.09
D
0.1
2
WB JEE 2020
+1
-0.25 As shown in the figure, a point charge q1 = + 1 $$\times$$ 10-6 C is placed at the origin in xy-plane and another point charge q2 = + 3 $$\times$$ 10-6 C is placed at the coordinate (10, 0). In that case, which of the following graph(s) shows most correctly the electric field vector in Ex in x-direction?
A B C D 3
WB JEE 2020
+1
-0.25 Four identical point masses, each of mass m and carrying charge + q are placed at the corners of a square of sides a on a frictionless plane surface. If the particles are released simultaneously, the kinetic energy of the system when they are infinitely far apart is
A
$${{{q^2}} \over a}(2\sqrt 2 + 1)$$
B
$${{{q^2}} \over a}(\sqrt 2 + 2)$$
C
$${{{q^2}} \over a}(\sqrt 2 + 4)$$
D
$${{{q^2}} \over a}(\sqrt 2 + 1)$$
4
WB JEE 2020
+1
-0.25 A very long charged solid cylinder of radius a contains a uniform charge density p. Dielectric constant of the material of the cylinder is K. What will be the magnitude of electric field at a radial distance x (x < a) from the axis of the cylinder?
A
$$p{x \over {{\varepsilon _0}}}$$
B
$$p{x \over {{2k\varepsilon _0}}}$$
C
$$p{{{x^2}} \over {2a{\varepsilon _0}}}$$
D
$$p{{{x^{}}} \over {2k}}$$
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