1
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
Choose the correct option relating wave lengths of different parts of electromagnetic wave spectrum:
A
$$\lambda$$radio waves > $$\lambda$$micro waves > $$\lambda$$visible > $$\lambda$$x-rays
B
$$\lambda$$visible > $$\lambda$$x-rays > $$\lambda$$radio waves > $$\lambda$$micro waves
C
$$\lambda$$visible < $$\lambda$$micro waves < $$\lambda$$radio waves < $$\lambda$$x-rays
D
$$\lambda$$x-rays < $$\lambda$$micro waves < $$\lambda$$radio waves < $$\lambda$$visible
2
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
Starting from the origin at time t = 0, with initial velocity 5$$\widehat j$$ ms-1 , a particle moves in the x-y plane with a constant acceleration of $$\left( {10\widehat i + 4\widehat j} \right)$$ ms-2. At time t, its coordinates are (20 m, y0 m). The values of t and y0 are, respectively:
A
5s and 25 m
B
2s and 18 m
C
2s and 24 m
D
4s and 52 m
3
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
Dimensional formula for thermal conductivity is (here K denotes the temperature):
A
MLT–3K–1
B
MLT–2K–2
C
MLT–2K
D
MLT–3K
4
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
Blocks of masses m, 2m, 4m and 8m are arranged in a line on a frictionless floor. Another block of mass m, moving with speed v along the same line (see figure) collides with mass m in perfectly inelastic manner. All the subsequent collisions are also perfectly inelastic. By the time the last block of mass 8m starts moving the total energy loss is p% of the original energy. Value of 'p' is close to :
A
37
B
77
C
87
D
94
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